feat: add batch session metadata lookup (#1408 )

A session browser may load only the 50 most recent conversations, while pinned sessions and saved folders refer to much older ones. After a restart, the client still has those IDs but needs their current titles, locations and archive state to rebuild the saved views. Finding a handful of retained sessions by paging through the entire history becomes increasingly expensive as that history grows. Add `_session/batch_get` to retrieve metadata for known session IDs in one request; the client chooses how many IDs to send per request. Successful results use the same row format as `session/list`, including archived sessions and sessions in worktrees, so the client can merge them with its recent page and apply its usual display filters. The response contains the sessions whose metadata is available, in request order. Other IDs are simply omitted. The client can refresh the rows it receives while keeping its saved references, so pinned and folder views stay independent of the recent-list window. --------- Co-authored-by: Aleksandr Slapoguzov <aleksandr.slapoguzov@jetbrains.com>
ci(deps): Bump the minor group with 3 updates (#1440 )
2026-10-27 04:30:59 +00:00 · 2026-10-27 00:44:18 +01:00 · 2026-10-26 16:18:48 +01:00 · 2026-10-26 14:15:14 +01:00 · 2026-10-26 13:46:13 +01:00 · 2026-10-26 12:34:13 +00:00
33 changed files with 2325 additions and 253 deletions
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -36,7 +36,7 @@ jobs:
      # Generating a GitHub token, so that PRs and tags created by
      # the release-please-action can trigger actions workflows.
      - name: Generate GitHub token
-        uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1
+        uses: actions/create-github-app-token@64ab729a6294000f5aa4a4bc0b73d1f32bc45510
        id: generate-token
        with:
          # GitHub App ID secret name
@@ -256,7 +256,7 @@ jobs:
          exit 1

      - name: Generate token scoped to the registry repo
-        uses: actions/create-github-app-token@bcd2ba49218906704ab6c1aa796996da409d3eb1
+        uses: actions/create-github-app-token@64ab729a6294000f5aa4a4bc0b73d1f32bc45510
        id: registry-token
        with:
          app-id: ${{ secrets.REGISTRY_UPDATER_APP_ID }}
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.95.0"
+  ".": "0.97.0"
 }
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,39 @@
 # Changelog

+## [0.97.0](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.96.0...v0.97.0) (2026-10-26)
+
+
+### Features
+
+* add ultracode session config option ([#1438](https://github.com/agentclientprotocol/claude-agent-acp/issues/1438)) ([de96cef](https://github.com/agentclientprotocol/claude-agent-acp/commit/de96cef382d8daf27301f1f90ae4b5e7f665f73a))
+
+
+### Bug Fixes
+
+* bump body-parser from 2.3.0 to 2.4.0 ([#1436](https://github.com/agentclientprotocol/claude-agent-acp/issues/1436)) ([c26e640](https://github.com/agentclientprotocol/claude-agent-acp/commit/c26e640915739dc7a3cd0664f8f5879098e0fd83))
+* distinguish model options with duplicate labels ([#1286](https://github.com/agentclientprotocol/claude-agent-acp/issues/1286)) ([434be13](https://github.com/agentclientprotocol/claude-agent-acp/commit/434be13a33141af8655c6f7c30f574841bf2279c))
+* keep the usage-limit error when it arrives after compaction ([#1377](https://github.com/agentclientprotocol/claude-agent-acp/issues/1377)) ([2a1525e](https://github.com/agentclientprotocol/claude-agent-acp/commit/2a1525e57cd89246d1a50993fd6ba335c4e634ca))
+* pass --settings before the auth status subcommand ([#1392](https://github.com/agentclientprotocol/claude-agent-acp/issues/1392)) ([6a33ded](https://github.com/agentclientprotocol/claude-agent-acp/commit/6a33dedcbb90e7bf9db91207f0edbf19ca6d705e))
+* preserve foreground fork reports until launch completes ([#1431](https://github.com/agentclientprotocol/claude-agent-acp/issues/1431)) ([e369479](https://github.com/agentclientprotocol/claude-agent-acp/commit/e369479f93b34f84a11103323d097c44df42e02e))
+* settle advisor tool results before completing turns ([#1247](https://github.com/agentclientprotocol/claude-agent-acp/issues/1247)) ([bed795d](https://github.com/agentclientprotocol/claude-agent-acp/commit/bed795d261620e6d5113e427a7196d94e66e7034))
+* settle live steers folded into autonomous cycles ([#1185](https://github.com/agentclientprotocol/claude-agent-acp/issues/1185)) ([a4957d1](https://github.com/agentclientprotocol/claude-agent-acp/commit/a4957d17c1e1a925ba3b72b29c5dcde4faabbe17))
+
+## [0.96.0](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.95.0...v0.96.0) (2026-10-26)
+
+
+### Features
+
+* report SendMessage delegations as linked session messages ([#1424](https://github.com/agentclientprotocol/claude-agent-acp/issues/1424)) ([739dde3](https://github.com/agentclientprotocol/claude-agent-acp/commit/739dde3ae5bb848bdb90e2c9150e2cc4687d480c))
+* report the model of each native subagent ([#1432](https://github.com/agentclientprotocol/claude-agent-acp/issues/1432)) ([c319e5e](https://github.com/agentclientprotocol/claude-agent-acp/commit/c319e5e542aabe353bb2c5e177e4c5853392b8c4))
+
+
+### Bug Fixes
+
+* do not hold an AIR load replay until the CLI starts ([#1433](https://github.com/agentclientprotocol/claude-agent-acp/issues/1433)) ([eb9d63e](https://github.com/agentclientprotocol/claude-agent-acp/commit/eb9d63e5fde9b8fd8fe692dfb3280faba6626a42))
+* refine RFD child models after a load, and retry a failed model update ([#1434](https://github.com/agentclientprotocol/claude-agent-acp/issues/1434)) ([9a8bf71](https://github.com/agentclientprotocol/claude-agent-acp/commit/9a8bf71d454fa85d03f55d4101a77e3ea7a149d0))
+* send subagents' current state after a load response ([#1423](https://github.com/agentclientprotocol/claude-agent-acp/issues/1423)) ([17a967b](https://github.com/agentclientprotocol/claude-agent-acp/commit/17a967b4dab78bbb9cf9fedae60e6821578dc5cb))
+* update to Claude Code 2.1.310 ([#1435](https://github.com/agentclientprotocol/claude-agent-acp/issues/1435)) ([2f3c6bb](https://github.com/agentclientprotocol/claude-agent-acp/commit/2f3c6bb7b3451a00cd77d7bb31c09e690ca220b3))
+
 ## [0.95.0](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.94.0...v0.95.0) (2026-10-23)


--- a/README.md
+++ b/README.md
@@ -17,6 +17,7 @@ This tool implements an ACP agent by using the official [Claude Agent SDK](https
 - Interactive (and background) terminals
 - Custom [Slash commands](https://docs.anthropic.com/en/docs/claude-code/slash-commands)
 - Client MCP servers
+- An Ultracode session config option, which turns on Claude Code's dynamic workflows for every task. It appears when dynamic workflows are enabled and the model supports ultracode (any model with `xhigh` effort)
 - `/mcp` in the chat: the MCP server status as a list. The adapter runs `/mcp reconnect`, `/mcp enable`, and `/mcp disable` through the SDK control API, because Claude Code refuses them in SDK mode. A reconnect of an ACP server that needs authentication starts MCP OAuth through URL elicitation
 - Session-scoped long-running goals for AIR through the [goal extension](docs/air-extensions.md#goal) under `_meta.jetbrains.air.goal`
 - Structured errors, recovery, and warnings through the opt-in [session failure extension](docs/air-extensions.md#session-failure)
--- a/docs/air-extensions.md
+++ b/docs/air-extensions.md
@@ -141,8 +141,8 @@ The `initialize` response of an AIR client carries the agent side of the extensi
 }
 ```

-The agent list does not depend on the capabilities that AIR declares, except `sessionIndex`: the agent lists it, together with `sessionArchive`, `sessionRename`, `sessionListSubscribe` and `sessionWorktrees`, only for a client that declared `sessionIndex`.
-An extension is active only when the client declared its capability. The client does not declare `sessionArchive`, `sessionRename`, `sessionListSubscribe` and `sessionWorktrees`.
+The agent list does not depend on the capabilities that AIR declares, except `sessionIndex`: the agent lists it, together with `sessionBatchGet`, `sessionArchive`, `sessionRename`, `sessionListSubscribe` and `sessionWorktrees`, only for a client that declared `sessionIndex`.
+An extension is active only when the client declared its capability. The client does not declare `sessionBatchGet`, `sessionArchive`, `sessionRename`, `sessionListSubscribe` and `sessionWorktrees`.
 The response to a client that is not AIR has no `_meta.jetbrains` key.

 ### Capabilities
@@ -158,6 +158,7 @@ The response to a client that is not AIR has no `_meta.jetbrains` key.
 | `planFile`               | yes                 | Sends the path of the plan file in place of the plan text of an ExitPlanMode.                                   | [Plan file](#plan-file)                                 |
 | `backgroundSubagents`    | yes                 | Ends a prompt turn at its result while background subagents still run.                                          | [Background subagents](#background-subagents)           |
 | `sessionIndex`           | on request          | Pages, orders and annotates `session/list`; adds rename, archive and a list subscription.                       | [Session index](#session-index)                         |
+| `sessionBatchGet`        | with `sessionIndex` | Supports `_session/batch_get` for metadata of known session IDs.                                                | [Batch get](#batch-get)                                 |
 | `sessionArchive`         | with `sessionIndex` | Nothing on its own: the agent lists it to tell that it supports `_session/archive` and `_session/unarchive`.    | [Archive](#archive)                                     |
 | `sessionRename`          | with `sessionIndex` | Nothing on its own: the agent lists it to tell that it supports `_session/rename`.                              | [Rename](#rename)                                       |
 | `sessionListSubscribe`   | with `sessionIndex` | Nothing on its own: the agent lists it to tell that it supports `_session/list/subscribe`.                      | [List subscription](#list-subscription)                 |
@@ -707,7 +708,7 @@ A non-empty plan also gets one clear-context choice with the same priority.
 After that choice, the adapter stops the old private Claude query and hides that internal rejection.
 It starts a new private query under the same ACP session.
 It continues the turn with `Implement the following plan:` and the complete plan.
-The mode, model, agent, effort, Fast mode, and turn usage stay the same.
+The mode, model, agent, effort, Fast mode, ultracode, and turn usage stay the same.
 The SDK cannot apply `allowedPrompts` again, so those hints do not survive the handoff.

 The adapter does not allow a callback only because the session mode is `bypassPermissions`.
@@ -1282,8 +1283,8 @@ The session index makes `session/list` a bounded, ordered page with row metadata

 AIR declares `sessionIndex` in `_meta.jetbrains.air.capabilities`.
 Unlike the other capabilities, the agent advertises `sessionIndex` only to a client that declared it, and never under ACP v2.
-Exactly when it advertises `sessionIndex`, the agent also advertises `sessionArchive` (it supports `_session/archive` and `_session/unarchive`), `sessionRename` (it supports `_session/rename`), `sessionListSubscribe` (it supports `_session/list/subscribe` and `_session/list/unsubscribe`) and `sessionWorktrees` (rows carry `agentWorktree`, see [List response](#list-response)).
-The client does not declare these four; declaring them without `sessionIndex` enables nothing.
+Exactly when it advertises `sessionIndex`, the agent also advertises `sessionBatchGet` (it supports `_session/batch_get`), `sessionArchive` (it supports `_session/archive` and `_session/unarchive`), `sessionRename` (it supports `_session/rename`), `sessionListSubscribe` (it supports `_session/list/subscribe` and `_session/list/unsubscribe`) and `sessionWorktrees` (rows carry `agentWorktree`, see [List response](#list-response)).
+The client does not declare these five; declaring them without `sessionIndex` enables nothing.
 Everything in this section applies only to such a client, except where [Delete and close](#delete-and-close) says otherwise.
 A client without the capability gets the `session/list` of before: the SDK `listSessions` call, pages of 1000 by file mtime, `offset:N` cursors, and no row `_meta`.
 It gets no new notification, and the adapter starts no watcher for it.
@@ -1442,6 +1443,71 @@ In all of the session index methods and in `session/delete`, a session id matche
 Loading an archived session does not unarchive it.
 The CLI cleanup still deletes old transcripts (`cleanupPeriodDays`), archived or not.

+### Batch get
+
+`_session/batch_get` refreshes metadata for retained session IDs, such as pinned
+sessions and folder members outside the recent list page. Check for
+`sessionBatchGet` in `initialize.result._meta.jetbrains.air.capabilities` before
+calling it.
+
+The params object must contain only `sessionIds`: an array of distinct,
+non-blank strings. IDs match exactly, without trimming or case normalization.
+Malformed params, duplicates or extra fields return `Invalid params` (`-32602`).
+The agent sets no limit on the number of IDs; the client chooses the batch size
+for the latency it accepts. Archived sessions and sessions in other projects
+or worktrees are eligible.
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 7,
+  "method": "_session/batch_get",
+  "params": { "sessionIds": ["oldA", "oldB", "oldC"] }
+}
+```
+
+```json
+{
+  "jsonrpc": "2.0",
+  "id": 7,
+  "result": {
+    "sessions": [
+      {
+        "sessionId": "oldA",
+        "cwd": "/project",
+        "title": "Fix the build",
+        "updatedAt": "2026-01-01T00:00:00.000Z",
+        "_meta": { "jetbrains": { "air": { "version": 1, "archived": false } } }
+      }
+    ]
+  }
+}
+```
+
+The example IDs are placeholders for stored Claude session UUIDs. `sessions`
+contains the same full rows as `session/list` without a project filter, including
+archived sessions and `_meta.jetbrains.air`. Copies use the same
+newest-readable-copy selection as the list. Returned sessions preserve their
+relative request order. Non-UUID IDs and IDs without a listable transcript are
+omitted: absent, empty, unreadable or malformed transcripts, sidechains, sessions
+whose continuation has history, and transcripts whose cwd cannot be recovered.
+A sidecar alone does not supply a row.
+
+`{ "sessionIds": [] }` returns `{ "sessions": [] }` without reading the store.
+A store-wide failure, such as an unreadable projects root, rejects the request.
+Individual results reflect the store as each ID is read.
+
+Lookup normally addresses only the requested transcript filenames in each project
+and reads their metadata. A transcript without a cwd can use a sibling's cwd,
+as the list does. This fallback enumerates and stats sibling transcripts only
+in the directories of rows still missing a cwd, then reads at most 64 siblings
+per directory, newest mtime first. A failed recovery is cached for 60 seconds
+unless the directory mtime changes. Other project histories are not enumerated.
+The agent looks up 100 IDs at a time; the client may request any number of IDs.
+Merge returned rows with the recent page by `sessionId`. A batch read does not
+expand an existing list subscription's scope; refresh retained IDs outside that
+scope explicitly.
+
 ### List subscription

 `_session/list/subscribe { "cwd": "…" }` returns `{ "subscriptionId": "…" }`.
@@ -1465,6 +1531,7 @@ From then on the agent sends `_session/list/changes` notifications for the sessi

 - `cwd` is required and must be an absolute path; a missing, non-string or relative `cwd` is `-32602`. Other parameters are ignored.
 - The scope is the sessions of `cwd` and of the same subdirectory in every existing linked worktree of its repository, as a list with `includeWorktrees: true` resolves it, in any archive state. Sidechain and subagent transcripts are left out, as in the list.
+- There is no page or recent-session limit: changes to older pinned or folder sessions within that scope are reported even outside the page AIR loaded. Pinned IDs outside the subscribed project and worktrees are not tracked; `_session/batch_get` does not add them to the subscription. AIR must subscribe to their project scope or refresh them explicitly.
 - `sessions` holds the full current row of each session in scope that appeared, or whose `title`, `lastPromptAt`, `state`, `lastTurnEndedAt`, `cost`, `model`, `forkedFrom`, `agentWorktree` or `archived` changed since the last row sent for it on this subscription. A row is exactly the row of `session/list`, `_meta.jetbrains.air` included.
 - After subscribe, the first change of each session sends its row in full, even when only `updatedAt` changed. From then on, a change of `updatedAt` alone sends nothing; the new `updatedAt` comes with the next change.
 - `removed` holds the ids of sessions that left the scope: deleted (the transcript is gone), or moved to a path outside it. It may name a session the client does not list (one it never listed, one the list hides, such as a session continued in another one when that one changes); the client ignores such an id.
@@ -1517,6 +1584,7 @@ Names and semantics follow them; the transport differs, and so do the `archived`
 | capability `sessionIndex` (`_meta.jetbrains.air`)                                                 | `sessionCapabilities.list.limit`                                                                                                                                                                                |
 | capability `sessionArchive` (`_meta.jetbrains.air`)                                               | `sessionCapabilities.archive` (#2161)                                                                                                                                                                           |
 | capability `sessionRename` (`_meta.jetbrains.air`)                                                | `sessionCapabilities.setTitle` (#1987)                                                                                                                                                                          |
+| capability `sessionBatchGet`, `_session/batch_get`                                                | none                                                                                                                                                                                                            |
 | `_meta.jetbrains.air.list.limit`                                                                  | `session/list` `limit`                                                                                                                                                                                          |
 | `_meta.jetbrains.air.list.includeWorktrees`                                                       | `session/list` `includeWorktrees`                                                                                                                                                                               |
 | `_meta.jetbrains.air.list.archived` (`"unarchived"`, `"archived"`, `"all"`)                       | `session/list` `archived` (#2161), a boolean there                                                                                                                                                              |
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,16 +1,16 @@
 {
  "name": "@agentclientprotocol/claude-agent-acp",
-  "version": "0.95.0",
+  "version": "0.97.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "@agentclientprotocol/claude-agent-acp",
-      "version": "0.95.0",
+      "version": "0.97.0",
      "license": "Apache-2.0",
      "dependencies": {
-        "@agentclientprotocol/sdk": "2.0.1",
-        "@anthropic-ai/claude-agent-sdk": "0.3.309",
+        "@agentclientprotocol/sdk": "2.0.2",
+        "@anthropic-ai/claude-agent-sdk": "0.3.310",
        "diff": "9.0.0",
        "zod": "4.6.7"
      },
@@ -18,7 +18,7 @@
        "claude-agent-acp": "dist/index.js"
      },
      "devDependencies": {
-        "@anthropic-ai/sdk": "1.1.0",
+        "@anthropic-ai/sdk": "1.3.0",
        "@eslint/js": "10.0.1",
        "@tsconfig/node22": "22.0.6",
        "@types/node": "26.6.5",
@@ -38,31 +38,31 @@
      }
    },
    "node_modules/@agentclientprotocol/sdk": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-2.0.1.tgz",
-      "integrity": "sha512-v4E/NcBTGFEKmorGso8ysAjJTkNh5UMJPP4aDznyMNmnP9t10g/aCCo/Djy7RYaYZy5ZROFK3G5cEj9tDgGOTQ==",
+      "version": "2.0.2",
+      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-2.0.2.tgz",
+      "integrity": "sha512-jLywRB42hZMRMc4aUgt0uRjkY9FQnMdybv4XgLl+ddi75QuJn8Vbl0+CHcVHJDC0+WDfi1KQXRWtHaR5vp6gHw==",
      "license": "Apache-2.0",
      "peerDependencies": {
        "zod": "^3.25.76 || ^4.0.0"
      }
    },
    "node_modules/@anthropic-ai/claude-agent-sdk": {
-      "version": "0.3.309",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk/-/claude-agent-sdk-0.3.309.tgz",
-      "integrity": "sha512-Tou0fXBkxKJDcgT09v3Iv/Jd7bNgapgfAiHxGPctAADPFQhidfhZbcv7at1cVL0Lon5sbs+OzP/pEOigw2TI0A==",
+      "version": "0.3.310",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk/-/claude-agent-sdk-0.3.310.tgz",
+      "integrity": "sha512-fo+sr+9Ks73P001f6XKRQlyzfIBAJMgXArLUkH5Tu98NikRDZeGtFQVj23d5/hj2ijpFgzffrr4fHywY9qUkoQ==",
      "license": "SEE LICENSE IN README.md",
      "engines": {
        "node": ">=18.0.0"
      },
      "optionalDependencies": {
-        "@anthropic-ai/claude-agent-sdk-darwin-arm64": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-darwin-x64": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-linux-arm64": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-linux-arm64-musl": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-linux-x64": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-linux-x64-musl": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-win32-arm64": "0.3.309",
-        "@anthropic-ai/claude-agent-sdk-win32-x64": "0.3.309"
+        "@anthropic-ai/claude-agent-sdk-darwin-arm64": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-darwin-x64": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-linux-arm64": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-linux-arm64-musl": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-linux-x64": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-linux-x64-musl": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-win32-arm64": "0.3.310",
+        "@anthropic-ai/claude-agent-sdk-win32-x64": "0.3.310"
      },
      "peerDependencies": {
        "@anthropic-ai/sdk": ">=0.93.0",
@@ -71,9 +71,9 @@
      }
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-darwin-arm64": {
-      "version": "0.3.309",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-arm64/-/claude-agent-sdk-darwin-arm64-0.3.309.tgz",
-      "integrity": "sha512-qC93iDGEioaXqWsYazcZzNv3hd8d4VHkCFgb+AzvbkCWOzZHnRu1EqF4Iz5kCTLDs4VdMvCa1NkzlUwtTedBVw==",
+      "version": "0.3.310",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-arm64/-/claude-agent-sdk-darwin-arm64-0.3.310.tgz",
+      "integrity": "sha512-gpzMjDZdcdA2Webuqm9j76exG8yNK/755ZYWbS3MM4vVBlAsm+enEO+hhNt0Mx1VMil28RWetvTO4ZJ3YODVMA==",
      "cpu": [
        "arm64"
      ],
@@ -84,9 +84,9 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-darwin-x64": {
-      "version": "0.3.309",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-x64/-/claude-agent-sdk-darwin-x64-0.3.309.tgz",
-      "integrity": "sha512-RvP0UOcYxn42c1lgByoMufHaMOH86U2ThGGFupOxBKATY4Q6WJd6M1CukQ/qygfgJ8lcxvK8GOOd3SIny4kQ8Q==",
+      "version": "0.3.310",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-x64/-/claude-agent-sdk-darwin-x64-0.3.310.tgz",
+      "integrity": "sha512-ZRQ4ZrzE2OOfR+Fx8h+CM4NKh0UiYqlh5TowP7HUhn5KUoYMjoSR/xIhix8ow42X2IDiBy0FjEVaA/Awhu2KAw==",
      "cpu": [
        "x64"
      ],
@@ -97,9 +97,9 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-linux-arm64": {
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@@ -1250,19 +1268,19 @@
      }
    },
    "node_modules/body-parser": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-2.3.0.tgz",
-      "integrity": "sha512-2cGmJupaNgg+QUwVLAucDuWuoMZ6EX9iHDRswZ5lsNYEmwPaRknMPCLZz07yTzVq/83p4o/wzbDZbBrTvGGTIw==",
+      "version": "2.4.0",
+      "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-2.4.0.tgz",
+      "integrity": "sha512-Ifk1KcLrxaGt1occQagQNFNNOqRt1LFuehEnHHzB8Z6cRgIxRU1TBaiIsUiCdA+gy5PL7Y1IX31DNKkRmxtXjQ==",
      "license": "MIT",
      "peer": true,
      "dependencies": {
        "bytes": "^3.1.2",
-        "content-type": "^2.0.0",
+        "content-type": "^2.1.0",
        "debug": "^4.4.3",
        "http-errors": "^2.0.1",
-        "iconv-lite": "^0.7.2",
+        "iconv-lite": "^0.7.3",
        "on-finished": "^2.4.1",
-        "qs": "^6.15.2",
+        "qs": "^6.16.1",
        "raw-body": "^3.0.2",
        "type-is": "^2.1.0"
      },
@@ -2927,9 +2945,9 @@
      }
    },
    "node_modules/on-finished": {
-      "version": "2.4.1",
-      "resolved": "https://registry.npmjs.org/on-finished/-/on-finished-2.4.1.tgz",
-      "integrity": "sha512-oVlzkg3ENAhCk2zdv7IJwd/QUD4z2RxRwpkcGY8psCVcCYZNq4wYnVWALHM+brtuJjePWiYF/ClmuDr8Ch5+kg==",
+      "version": "2.4.2",
+      "resolved": "https://registry.npmjs.org/on-finished/-/on-finished-2.4.2.tgz",
+      "integrity": "sha512-ATWUv387i+nLD49EiDoOft5scf32Vsdz3ktrQJG9bi7jRFmaXTssvyvj1EmeKVVgvesbqUtvQQvaS2TpTukAZQ==",
      "license": "MIT",
      "peer": true,
      "dependencies": {
@@ -2937,6 +2955,10 @@
      },
      "engines": {
        "node": ">= 0.8"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/express"
      }
    },
    "node_modules/once": {
@@ -3231,14 +3253,14 @@
      }
    },
    "node_modules/rolldown": {
-      "version": "1.2.14",
-      "resolved": "https://registry.npmjs.org/rolldown/-/rolldown-1.2.14.tgz",
-      "integrity": "sha512-eTBTTqMR6uHKLgcUqpJP8ntzDI6V4LYA8negAMBEI7gkgVvOdrx6VsvS2Ym+83KhOPdLCHWJu0w7UQFJZhHKNw==",
+      "version": "1.2.15",
+      "resolved": "https://registry.npmjs.org/rolldown/-/rolldown-1.2.15.tgz",
+      "integrity": "sha512-6odND+fel5zVw3I4Yc2e69gvguDnX0CAAGiNDZSq4ik5WUcaLrkD2GLuog0XcODbor31hZ5ayEMgVDno+KPV5g==",
      "dev": true,
      "license": "MIT",
      "peer": true,
      "dependencies": {
-        "@oxc-project/types": "=0.154.0",
+        "@oxc-project/types": "=0.155.0",
        "@rolldown/pluginutils": "^1.0.0"
      },
      "bin": {
@@ -3248,21 +3270,21 @@
        "node": "^20.19.0 || >=22.12.0"
      },
      "optionalDependencies": {
-        "@rolldown/binding-android-arm-eabi": "1.2.14",
-        "@rolldown/binding-android-arm64": "1.2.14",
-        "@rolldown/binding-darwin-arm64": "1.2.14",
-        "@rolldown/binding-darwin-x64": "1.2.14",
-        "@rolldown/binding-freebsd-x64": "1.2.14",
-        "@rolldown/binding-linux-arm-gnueabihf": "1.2.14",
-        "@rolldown/binding-linux-arm64-gnu": "1.2.14",
-        "@rolldown/binding-linux-arm64-musl": "1.2.14",
-        "@rolldown/binding-linux-ppc64-gnu": "1.2.14",
-        "@rolldown/binding-linux-s390x-gnu": "1.2.14",
-        "@rolldown/binding-linux-x64-gnu": "1.2.14",
-        "@rolldown/binding-linux-x64-musl": "1.2.14",
-        "@rolldown/binding-openharmony-arm64": "1.2.14",
-        "@rolldown/binding-win32-arm64-msvc": "1.2.14",
-        "@rolldown/binding-win32-x64-msvc": "1.2.14"
+        "@rolldown/binding-android-arm-eabi": "1.2.15",
+        "@rolldown/binding-android-arm64": "1.2.15",
+        "@rolldown/binding-darwin-arm64": "1.2.15",
+        "@rolldown/binding-darwin-x64": "1.2.15",
+        "@rolldown/binding-freebsd-x64": "1.2.15",
+        "@rolldown/binding-linux-arm-gnueabihf": "1.2.15",
+        "@rolldown/binding-linux-arm64-gnu": "1.2.15",
+        "@rolldown/binding-linux-arm64-musl": "1.2.15",
+        "@rolldown/binding-linux-ppc64-gnu": "1.2.15",
+        "@rolldown/binding-linux-s390x-gnu": "1.2.15",
+        "@rolldown/binding-linux-x64-gnu": "1.2.15",
+        "@rolldown/binding-linux-x64-musl": "1.2.15",
+        "@rolldown/binding-openharmony-arm64": "1.2.15",
+        "@rolldown/binding-win32-arm64-msvc": "1.2.15",
+        "@rolldown/binding-win32-x64-msvc": "1.2.15"
      }
    },
    "node_modules/router": {
@@ -3655,17 +3677,17 @@
      }
    },
    "node_modules/vite": {
-      "version": "8.3.4",
-      "resolved": "https://registry.npmjs.org/vite/-/vite-8.3.4.tgz",
-      "integrity": "sha512-IftLE8phJhdNRIGNEV4JCCvfNScoZQVfcXaN8TQropWGJtOHcu+iAB9pHcuGvmEb/kddw0LBe/jS8ztdC6xdiQ==",
+      "version": "8.3.5",
+      "resolved": "https://registry.npmjs.org/vite/-/vite-8.3.5.tgz",
+      "integrity": "sha512-z1YpjieJ9g0ebTmQpLBv/oq9E3F9EIlOe+7LahW8SrE3LTiG3udBRUXQOlYXP9b+IC2q2phHeVxj9xGlw34OEQ==",
      "dev": true,
      "license": "MIT",
      "peer": true,
      "dependencies": {
        "lightningcss": "^1.33.0",
        "picomatch": "^4.0.7",
-        "postcss": "^8.5.29",
-        "rolldown": "~1.2.12",
+        "postcss": "^8.5.30",
+        "rolldown": "~1.2.14",
        "tinyglobby": "^0.2.17"
      },
      "bin": {
@@ -3682,7 +3704,7 @@
      },
      "peerDependencies": {
        "@types/node": "^20.19.0 || >=22.12.0",
-        "@vitejs/devtools": "^0.7.1",
+        "@vitejs/devtools": "^0.7.1 || ^0.8.0",
        "esbuild": "^0.27.0 || ^0.28.0",
        "jiti": ">=1.21.0",
        "less": "^4.0.0",
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
  "publishConfig": {
    "access": "public"
  },
-  "version": "0.95.0",
+  "version": "0.97.0",
  "description": "An ACP-compatible coding agent powered by the Claude Agent SDK (TypeScript)",
  "main": "dist/lib.js",
  "types": "dist/lib.d.ts",
@@ -65,13 +65,13 @@
    "node": ">=22"
  },
  "dependencies": {
-    "@agentclientprotocol/sdk": "2.0.1",
-    "@anthropic-ai/claude-agent-sdk": "0.3.309",
+    "@agentclientprotocol/sdk": "2.0.2",
+    "@anthropic-ai/claude-agent-sdk": "0.3.310",
    "diff": "9.0.0",
    "zod": "4.6.7"
  },
  "devDependencies": {
-    "@anthropic-ai/sdk": "1.1.0",
+    "@anthropic-ai/sdk": "1.3.0",
    "@eslint/js": "10.0.1",
    "@tsconfig/node22": "22.0.6",
    "@types/node": "26.6.5",
--- a/src/acp-agent.ts
+++ b/src/acp-agent.ts
@@ -147,7 +147,11 @@ import {
  withAirMeta,
 } from "./air-extension.js";
 import * as sessionIndex from "./session-index/connection.js";
-import type { RenameSessionRequest, SessionIdRequest } from "./session-index/service.js";
+import type {
+  BatchGetSessionsRequest,
+  RenameSessionRequest,
+  SessionIdRequest,
+} from "./session-index/service.js";
 import type {
  ListSubscribeRequest,
  ListUnsubscribeRequest,
@@ -365,6 +369,15 @@ import {
  mergeEffortSettings,
  settingsEffortForModel,
 } from "./session-effort.js";
+import {
+  createUltracodeConfigOption,
+  readUltracodeSettings,
+  resolveUltracodeEnabled,
+  ULTRACODE_CONFIG_ID,
+  ultracodeSupported,
+  ultracodeWorkflowsEnabled,
+  type UltracodeOptionState,
+} from "./session-ultracode.js";

 export { EFFORT_CONFIG_ID, settingsEffortForModel } from "./session-effort.js";
 export {
@@ -1191,6 +1204,15 @@ export type Session = {
   *  user's intent so it persists across model switches; the Fast mode config
   *  option is only surfaced while the selected model supports it. */
  fastModeEnabled: boolean;
+  /** Whether ultracode is turned on for this session. Tracked as the user's
+   *  intent, like `fastModeEnabled`: the CLI keeps the request across model
+   *  switches and applies it whenever the model supports ultracode, while the
+   *  config option is only surfaced on supporting models. */
+  ultracodeEnabled: boolean;
+  /** Whether dynamic workflows are enabled, learned from the CLI's
+   *  `get_settings` at session start; undefined when unknown. Combined with
+   *  the model's support to decide whether to show the ultracode option. */
+  ultracodeWorkflowsEnabled?: boolean;
  /** The non-default effort the user picked through the ACP picker this
   *  session. A pin lives at the SDK's flag layer, which overrides the CLI's
   *  persisted effort (including the per-model `modelSettings` entries), so it
@@ -2801,6 +2823,7 @@ export class ClaudeAcpAgent {
        return session;
      },
      applyFastMode: (session, enabled) => this.applyFastMode(session, enabled),
+      applyUltracode: (session, enabled) => this.applyUltracode(session, enabled),
      sessionUpdate: (notification) => this.client.sessionUpdate(notification),
      supportsPlanOperations: () => this.clientCapabilities?.plan != null,
      ensureConsumer: (session, id) => this.ensureConsumer(session, id),
@@ -3116,7 +3139,10 @@ export class ClaudeAcpAgent {
    }
    timing.phase("session-ready");
    const replayed = await replay;
-    if (!replayed.ok) throw replayed.error;
+    if (!replayed.ok) {
+      this.replayedChildModels.delete(params.sessionId);
+      throw replayed.error;
+    }
    return {
      sessionId: response.sessionId,
      modes: response.modes,
@@ -3227,7 +3253,7 @@ export class ClaudeAcpAgent {
    return this.sessionIndex.clientTitle(title);
  }

-  /** `_session/list/subscribe`, `_session/list/unsubscribe`, `_session/rename`,
+  /** `_session/batch_get`, `_session/list/subscribe`, `_session/list/unsubscribe`, `_session/rename`,
   *  `_session/archive`, `_session/unarchive`. */
  async subscribeSessionList(params: ListSubscribeRequest) {
    return this.sessionIndex.subscribeList(params);
@@ -3235,6 +3261,9 @@ export class ClaudeAcpAgent {
  async unsubscribeSessionList(params: ListUnsubscribeRequest) {
    return this.sessionIndex.unsubscribeList(params);
  }
+  async batchGetSessions(params: BatchGetSessionsRequest) {
+    return this.sessionIndex.batchGet(params);
+  }
  renameSessionTitle(params: RenameSessionRequest) {
    return this.sessionIndex.rename(params);
  }
@@ -3427,7 +3456,9 @@ export class ClaudeAcpAgent {
    try {
      const cliPath = await claudeCliPath();
      const args = ["auth", "status", "--json"];
-      if (context?.override) args.push("--settings", JSON.stringify(context.override));
+      // `--settings` is a global CLI option: after the `auth status` subcommand the CLI rejects
+      // it with "unknown option '--settings'", so it has to come first.
+      if (context?.override) args.unshift("--settings", JSON.stringify(context.override));
      ({ stdout } = await execFileAsync(cliPath, args, {
        timeout: AUTH_STATUS_PROBE_TIMEOUT_MS,
        cwd: context?.manager.getCwd() ?? process.cwd(),
@@ -5084,6 +5115,8 @@ export class ClaudeAcpAgent {
     *  marked as a background result, but it lists the uuids of the prompts it
     *  answered.
     *
+     *  A steer belongs to the live active turn even though it has no queued
+     *  Turn of its own. Its stamped result can answer that turn too.
     *  A turn held open for its background subagents already has its result,
     *  so a result that names it does not answer it. */
    const answersPendingPrompt = (message: {
@@ -5099,8 +5132,15 @@ export class ClaudeAcpAgent {
        answeredPromptUuids = [message.user_message_uuid];
      }

+      const activeTurn = session.activeTurn;
+      const liveActiveTurn =
+        activeTurn && !activeTurn.settled && !isHeldOpen(activeTurn) ? activeTurn : undefined;
      for (const promptUuid of answeredPromptUuids) {
-        const turn = findUnsettledTurn(promptUuid);
+        // Keep queued prompt matching, including folded sends with no echo.
+        // Steers qualify only through their live active owner.
+        const turn =
+          findUnsettledTurn(promptUuid) ??
+          (liveActiveTurn?.steeredUuids?.has(promptUuid) ? liveActiveTurn : undefined);
        if (turn === undefined) {
          // Not a prompt of this session, or it was answered already.
          continue;
@@ -8042,6 +8082,13 @@ export class ClaudeAcpAgent {
              message.message.model === "<synthetic>" &&
              compaction.hasDeliveredOutput
            ) {
+              if (isSyntheticUsageLimitMessage(message.message)) {
+                lastAssistantWasUsageLimit = true;
+                lastAssistantFailureTitle = assistantMessageText(message.message);
+                if (message.error) {
+                  lastAssistantError = message.error;
+                }
+              }
              break;
            }

@@ -8197,6 +8244,7 @@ export class ClaudeAcpAgent {
            }

            let content: typeof message.message.content;
+            let toolUseResult = message.type === "user" ? message.tool_use_result : undefined;
            if (
              message.type === "assistant" &&
              (message.parent_tool_use_id === null || forwardsSubagentText())
@@ -8217,6 +8265,20 @@ export class ClaudeAcpAgent {
                (item) => item.type !== "text" && item.type !== "thinking",
              );
              streamedBlocksOf(message.parent_tool_use_id).length = 0;
+            } else if (
+              message.parent_tool_use_id !== null &&
+              Array.isArray(message.message.content)
+            ) {
+              // A foreground fork inherits a placeholder result for its own
+              // launch. Only the launching side can complete that Agent call
+              // with the fork's actual report.
+              const launchId = message.parent_tool_use_id;
+              content = message.message.content.filter(
+                (block) => block.type !== "tool_result" || block.tool_use_id !== launchId,
+              );
+              // The message-level sidecar cannot describe a remaining result
+              // after its launch result was removed.
+              if (content.length !== message.message.content.length) toolUseResult = undefined;
            } else {
              content = message.message.content;
            }
@@ -8234,7 +8296,7 @@ export class ClaudeAcpAgent {
              );
              const backgroundBashTask = backgroundBashTaskFromToolResult(
                content,
-                message.tool_use_result,
+                toolUseResult,
                session.toolUseCache,
              );
              if (backgroundBashTask) await asyncTasks.taskBackgrounded(backgroundBashTask);
@@ -8263,7 +8325,7 @@ export class ClaudeAcpAgent {
                asyncTasks,
                backgroundBashTask,
              );
-              const resumedAgentId = resumedNativeSubagentId(message.tool_use_result);
+              const resumedAgentId = resumedNativeSubagentId(toolUseResult);
              if (resumedAgentId) {
                const resume = sendMessageResume(
                  session.toolUseCache,
@@ -8304,7 +8366,7 @@ export class ClaudeAcpAgent {
                emittedToolCalls: session.emittedToolCalls,
                toolCallFields: toolCallFieldsOf(session),
                messageId: messageIdForGrouping(message),
-                toolUseResult: message.type === "user" ? message.tool_use_result : undefined,
+                toolUseResult,
                // On the wire since CLI 2.1.216 but not in SDKUserMessage's
                // type, hence the cast. Validated by parseToolResultMeta.
                toolResultMeta:
@@ -9167,13 +9229,18 @@ export class ClaudeAcpAgent {
      throw new Error(`Unknown config option: ${params.configId}`);
    }

-    // Fast mode carries a boolean value (for Clients that opted into boolean
-    // config options) or the "on"/"off" select fallback, so it bypasses the
+    // Fast mode and ultracode carry a boolean value (for Clients that opted
+    // into boolean config options) or the "on"/"off" select fallback, so they
+    // bypass the
    // string-only validation the select-style options below rely on.
    if (params.configId === FAST_MODE_CONFIG_ID) {
      await this.applyFastMode(session, resolveFastModeEnabled(params));
      return { configOptions: session.configOptions };
    }
+    if (params.configId === ULTRACODE_CONFIG_ID) {
+      await this.applyUltracode(session, resolveUltracodeEnabled(params));
+      return { configOptions: session.configOptions };
+    }

    if (typeof params.value !== "string") {
      throw new Error(`Invalid value for config option ${params.configId}: ${params.value}`);
@@ -9449,7 +9516,8 @@ export class ClaudeAcpAgent {
        ? new RfdSubagentReplay(
            rfdHistory,
            (notification) => this.client.sessionUpdate(asSdkSessionNotification(notification)),
-            replayModels,
+            this.subagentModels(sessionId),
+            !pending,
          )
        : undefined;
    rfdReplay?.scan(messages, sessionId);
@@ -11001,6 +11069,13 @@ export class ClaudeAcpAgent {
        {
          useRecommendedValue,
        },
+        {
+          // Like Fast mode, the toggle hides on models without ultracode
+          // support and comes back with the retained intent on one that has it.
+          supported: ultracodeSupported(session.ultracodeWorkflowsEnabled, newModelInfo),
+          enabled: session.ultracodeEnabled,
+          useBooleanOption: clientSupportsBooleanConfigOptions(this.clientCapabilities),
+        },
      );

      // Opted-in clients apply the concrete displayed effort on every switch,
@@ -11027,10 +11102,7 @@ export class ClaudeAcpAgent {
            // deliberately apply their concrete displayed effort.
            effortFlagSettings(
              useRecommendedValue ? newEffort : undefined,
-              mergeEffortSettings(
-                session.settingsManager.getSettings(),
-                session.effortSettingsOverride,
-              ),
+              session.ultracodeEnabled,
            ),
          );
          session.effortPinnedLevel = effortPinnedForNewModel ? pinnedEffort : undefined;
@@ -11099,15 +11171,7 @@ export class ClaudeAcpAgent {
    } else if (configId === EFFORT_CONFIG_ID) {
      // Apply first so a rejected control request cannot leave the displayed
      // value ahead of the SDK flag layer.
-      await session.query.applyFlagSettings(
-        effortFlagSettings(
-          value,
-          mergeEffortSettings(
-            session.settingsManager.getSettings(),
-            session.effortSettingsOverride,
-          ),
-        ),
-      );
+      await session.query.applyFlagSettings(effortFlagSettings(value, session.ultracodeEnabled));
      session.configOptions = session.configOptions.map((o) =>
        o.id === configId && typeof o.currentValue === "string" ? { ...o, currentValue: value } : o,
      );
@@ -11189,6 +11253,22 @@ export class ClaudeAcpAgent {
    this.refreshFastModeOption(session, enabled);
  }

+  /** Turn ultracode on or off for a session. Sends an explicit boolean, which
+   *  leaves the effort level alone (`null` would reset the flag layer instead).
+   *  The SDK flag is applied first so a rejected request leaves the session
+   *  state and option untouched. */
+  private async applyUltracode(session: Session, enabled: boolean): Promise<void> {
+    await session.query.applyFlagSettings({ ultracode: enabled });
+    session.ultracodeEnabled = enabled;
+    const refreshed = createUltracodeConfigOption(
+      enabled,
+      clientSupportsBooleanConfigOptions(this.clientCapabilities),
+    );
+    session.configOptions = session.configOptions.map((o) =>
+      o.id === ULTRACODE_CONFIG_ID ? refreshed : o,
+    );
+  }
+
  /** Reconcile the session's Fast mode toggle with an SDK-reported
   *  `fast_mode_state` (delivered on `system`/init and on user-turn `result`s).
   *  The SDK can flip fast mode independently of the user — e.g. back to `on`
@@ -12027,6 +12107,21 @@ export class ClaudeAcpAgent {
        settingsManager.getSettings(),
        configuredSettingsObject,
      );
+
+      // The CLI reports whether ultracode can run (workflows enabled and a
+      // supporting model) and whether the session already requests it (an
+      // `ultracode: true` setting). Without a report, fall back to settings.
+      const ultracodeReport = await readUltracodeSettings(q);
+      timing.phase("ultracode");
+      const ultracodeEnabled = ultracodeReport?.requested ?? effortSettings.ultracode === true;
+      const workflowsEnabled = ultracodeWorkflowsEnabled(ultracodeReport, currentModelInfo);
+      const ultracode: UltracodeOptionState = {
+        supported:
+          ultracodeReport?.available ?? ultracodeSupported(workflowsEnabled, currentModelInfo),
+        enabled: ultracodeEnabled,
+        useBooleanOption: clientSupportsBooleanConfigOptions(this.clientCapabilities),
+      };
+
      const configOptions = buildConfigOptions(
        modes,
        models,
@@ -12038,10 +12133,11 @@ export class ClaudeAcpAgent {
        {
          useRecommendedValue,
        },
+        ultracode,
      );
      const initialEffort = configOptions.find((option) => option.id === EFFORT_CONFIG_ID);
      if (useRecommendedValue && typeof initialEffort?.currentValue === "string") {
-        await q.applyFlagSettings(effortFlagSettings(initialEffort.currentValue, effortSettings));
+        await q.applyFlagSettings(effortFlagSettings(initialEffort.currentValue, ultracodeEnabled));
      }
      // Seed the context window without awaited IPC. The cached authoritative
      // window from a prior turn wins (`result.modelUsage`, cross-session),
@@ -12109,6 +12205,8 @@ export class ClaudeAcpAgent {
        currentAgent,
        fastModeEnabled,
        fastModeDisabledReason,
+        ultracodeEnabled,
+        ultracodeWorkflowsEnabled: workflowsEnabled,
        abortController,
        emitRawSDKMessages: sessionMeta?.claudeCode?.emitRawSDKMessages ?? false,
        forwardSubagentText,
@@ -12938,6 +13036,7 @@ export function buildConfigOptions(
  currentAgent: string = DEFAULT_AGENT_ID,
  fastMode?: FastModeOptionState,
  presentation?: ConfigOptionPresentation,
+  ultracode?: UltracodeOptionState,
 ): SessionConfigOption[] {
  const options: SessionConfigOption[] = [SessionModeManager.configOption(modes)];
  // A gateway that lists none of the SDK's models leaves no model to offer, so
@@ -12968,6 +13067,12 @@ export function buildConfigOptions(
    );
  }

+  // Surface the ultracode toggle only while the CLI can run it: dynamic
+  // workflows are enabled and the current model supports it.
+  if (ultracode?.supported) {
+    options.push(createUltracodeConfigOption(ultracode.enabled, ultracode.useBooleanOption));
+  }
+
  // Only surface the Agent picker when there's a real choice — i.e. the user
  // has configured at least one custom agent (built-ins are filtered out in
  // discoverCustomAgents). With none configured, "Default" would be the only
@@ -13610,6 +13715,38 @@ export function toAcpNotifications(
        break;
      }

+      case "advisor_tool_result": {
+        // Advisor results arrive in assistant content, including encrypted advice.
+        // Resolve the server tool through the normal result path without rendering
+        // opaque ciphertext. Server tools have no later PostToolUse hook to await.
+        const result = chunk.content;
+        unregisterHookCallback(chunk.tool_use_id);
+        output.push(
+          ...toAcpNotifications(
+            [
+              {
+                type: "tool_result",
+                tool_use_id: chunk.tool_use_id,
+                is_error: result.type === "advisor_tool_result_error",
+                content:
+                  result.type === "advisor_result"
+                    ? result.text
+                    : result.type === "advisor_redacted_result"
+                      ? "Advisor guidance applied server-side."
+                      : `Advisor error: ${result.error_code}`,
+              },
+            ],
+            role,
+            sessionId,
+            toolUseCache,
+            client,
+            logger,
+            options,
+          ),
+        );
+        break;
+      }
+
      case "tool_result":
      case "tool_search_tool_result":
      case "web_fetch_tool_result":
@@ -13779,7 +13916,6 @@ export function toAcpNotifications(
      case "container_upload":
      case "compaction":
      case "compaction_delta":
-      case "advisor_tool_result":
      case "fallback":
      case "mcp_tool_listing":
        break;
--- a/src/air-extension.ts
+++ b/src/air-extension.ts
@@ -22,6 +22,9 @@ export const AIR_PLAN_FILE_CAPABILITY = "planFile";
 * subscription. Advertised only to a client that declares it.
 */
 export const AIR_SESSION_INDEX_CAPABILITY = "sessionIndex";
+/** Metadata lookup of known ids with `_session/batch_get`. Advertised
+ *  exactly when {@link AIR_SESSION_INDEX_CAPABILITY} is negotiated. */
+export const AIR_SESSION_BATCH_GET_CAPABILITY = "sessionBatchGet";
 /**
 * The agent supports `_session/archive` and `_session/unarchive`. Advertised
 * exactly when {@link AIR_SESSION_INDEX_CAPABILITY} is; the client does not
--- a/src/clear-context-coordinator.ts
+++ b/src/clear-context-coordinator.ts
@@ -39,6 +39,7 @@ export type ClearContextSession<Turn extends ClearContextTurn = ClearContextTurn
  configOptions: SessionConfigOption[];
  currentAgent: string;
  fastModeEnabled: boolean;
+  ultracodeEnabled: boolean;
  effortPinnedLevel?: string;
  activeTurn?: Turn | null;
  turnQueue?: Turn[];
@@ -59,6 +60,7 @@ export type ClearContextCoordinatorHost<
    options: { publicSessionId: string; permissionMode: PermissionMode },
  ): Promise<Session>;
  applyFastMode(session: Session, enabled: boolean): Promise<void>;
+  applyUltracode(session: Session, enabled: boolean): Promise<void>;
  publishSessionState(
    sessionId: string,
    mode: PermissionMode,
@@ -146,6 +148,16 @@ export async function continuePlanInFreshContext<
    }
    assertRestartActive(freshSession);
  }
+  // The fresh query seeds ultracode from settings only, so a toggle made
+  // during the old session would otherwise be lost.
+  if (oldSession.ultracodeEnabled !== freshSession.ultracodeEnabled) {
+    try {
+      await host.applyUltracode(freshSession, oldSession.ultracodeEnabled);
+    } catch (error) {
+      host.logError("Failed to restore ultracode after clearing context:", error);
+    }
+    assertRestartActive(freshSession);
+  }

  oldSession.activeTurn = null;
  oldSession.turnQueue = [];
--- a/src/native-subagents.ts
+++ b/src/native-subagents.ts
@@ -90,6 +90,8 @@ export type SubagentModels = {
 type ChildConfiguration = {
  options: Map<string, SessionConfigOption>;
  published?: string;
+  /** The `model` option value and name that the client last got. */
+  publishedModel?: ModelEntry;
  publishing: Promise<void>;
 };

@@ -285,13 +287,13 @@ export class NativeSubagentRuntime {
    if (!entry) return;
    // Every response of a child reports its model: most repeat the model that
    // the client already has, and need no routing.
+    // A publication that failed sent nothing, so only the published model counts.
    const child = this.childByParentToolUse.get(parentToolUseId!);
-    const current = child?.announced
-      ? this.configBySession.get(child.sessionId)?.options.get(MODEL_CONFIG_ID)
-      : undefined;
-    if (current?.type === "select" && current.currentValue === entry.value) {
-      const shown = current.options[0];
-      if (shown && "name" in shown && shown.name === entry.name) return;
+    if (
+      child?.announced &&
+      sameModelEntry(this.configBySession.get(child.sessionId)?.publishedModel, entry)
+    ) {
+      return;
    }
    await deliver({
      sessionId: this.rootSessionId,
@@ -384,6 +386,11 @@ export class NativeSubagentRuntime {
        },
      });
      config.published = snapshot;
+      const model = configOptions.find((option) => option.id === MODEL_CONFIG_ID);
+      const shown = model?.type === "select" ? model.options[0] : undefined;
+      if (model && shown && "name" in shown && typeof model.currentValue === "string") {
+        config.publishedModel = { value: model.currentValue, name: shown.name };
+      }
    });
    // The caller receives the error; later observations must still be able to retry.
    config.publishing = publishing.catch(() => {});
@@ -1418,12 +1425,15 @@ export class NativeSubagentRuntime {

  private buffer(parentToolUseId: string, notification: AcpSessionNotification): void {
    const updates = this.pending.get(parentToolUseId);
-    // A child reports its model with each response before its announcement.
-    // Only the latest configuration waits, so they do not fill the buffer.
-    if (notification.update.sessionUpdate === "config_option_update" && updates) {
-      const index = updates.findIndex(
-        ({ update }) => update.sessionUpdate === "config_option_update",
-      );
+    // A child reports its model with each response before its announcement
+    // (see `reportModel`). Only the latest such report waits, so they do not
+    // fill the buffer. Any other configuration update waits as it is.
+    const modelOnly = ({ update }: AcpSessionNotification) =>
+      update.sessionUpdate === "config_option_update" &&
+      update.configOptions.length === 1 &&
+      update.configOptions[0]?.id === MODEL_CONFIG_ID;
+    if (updates && modelOnly(notification)) {
+      const index = updates.findIndex(modelOnly);
      if (index >= 0) {
        updates[index] = notification;
        return;
--- a/src/session-config-ids.ts
+++ b/src/session-config-ids.ts
@@ -2,3 +2,4 @@
 export const DEFAULT_MODEL_ID = "default";
 export const DEFAULT_AGENT_ID = "default";
 export const EFFORT_CONFIG_ID = "effort";
+export const ULTRACODE_CONFIG_ID = "ultracode";
--- a/src/session-effort.ts
+++ b/src/session-effort.ts
@@ -14,14 +14,15 @@ export function toSdkEffortLevel(value: string | undefined): EffortLevel | null

 // Since CLI 2.1.284 an `effortLevel` that changes the level, sent without an
 // `ultracode` key, turns ultracode off. The CLI's own effort control keeps
-// ultracode on at any level, so carry a settings-requested ultracode along
-// with every effort apply.
+// ultracode on at any level, so send `ultracode: true` with every effort apply
+// while the session has ultracode on. When it is off, the key is omitted: an
+// effort change then leaves ultracode off, as it already was.
 export function effortFlagSettings(
  value: string | undefined,
-  settings: Settings,
+  ultracode: boolean,
 ): { effortLevel: EffortLevel | null; ultracode?: true } {
  const effortLevel = toSdkEffortLevel(value);
-  return settings.ultracode === true ? { effortLevel, ultracode: true } : { effortLevel };
+  return ultracode ? { effortLevel, ultracode: true } : { effortLevel };
 }

 function canonicalizeModelSettingsKey(value: string): string {
--- a/src/session-index/connection.ts
+++ b/src/session-index/connection.ts
@@ -20,6 +20,7 @@ import type { Query } from "@anthropic-ai/claude-agent-sdk";
 import type { AcpClient, Logger, Session } from "../acp-agent.js";
 import {
  AIR_SESSION_ARCHIVE_CAPABILITY,
+  AIR_SESSION_BATCH_GET_CAPABILITY,
  AIR_SESSION_INDEX_CAPABILITY,
  AIR_SESSION_LIST_SUBSCRIBE_CAPABILITY,
  AIR_SESSION_RENAME_CAPABILITY,
@@ -46,6 +47,8 @@ import {
  renameTo,
  parseRenameSessionRequest,
  parseSessionIdRequest,
+  parseBatchGetSessionsRequest,
+  SESSION_BATCH_GET_METHOD,
  SESSION_ARCHIVE_METHOD,
  SESSION_RENAME_METHOD,
  SESSION_UNARCHIVE_METHOD,
@@ -54,6 +57,8 @@ import {
  type RetitleOptions,
  type SessionIdRequest,
  type TitleChange,
+  type BatchGetSessionsRequest,
+  type BatchGetSessionsResponse,
 } from "./service.js";

 /** What the session index keeps on each `Session`. */
@@ -144,12 +149,13 @@ export class SessionIndexConnection {
  }

  /** The AIR capabilities the agent advertises for the index: the index
-   *  itself, archive, rename, the list subscription and the `agentWorktree`
+   *  itself, batch get, archive, rename, the list subscription and the `agentWorktree`
   *  row field, all only to a client that declared `sessionIndex`. */
  capabilities(): string[] {
    return this.service
      ? [
          AIR_SESSION_INDEX_CAPABILITY,
+          AIR_SESSION_BATCH_GET_CAPABILITY,
          AIR_SESSION_ARCHIVE_CAPABILITY,
          AIR_SESSION_RENAME_CAPABILITY,
          AIR_SESSION_LIST_SUBSCRIBE_CAPABILITY,
@@ -230,6 +236,12 @@ export class SessionIndexConnection {
    return this.service?.list(params, (sessionId) => this.ownSessionState(sessionId));
  }

+  batchGet(params: BatchGetSessionsRequest): Promise<BatchGetSessionsResponse> {
+    return this.requireService(SESSION_BATCH_GET_METHOD).batchGet(params, (sessionId) =>
+      this.ownSessionState(sessionId),
+    );
+  }
+
  /** An AIR client archives with session/delete (see {@link deleteSession}):
   *  its archived sessions (an archived custom title) stay hidden from the
   *  old list, as when the delete removed them. */
@@ -448,6 +460,7 @@ export class SessionIndexConnection {

 /** The agent methods behind the session index extension methods. */
 type SessionIndexMethods = {
+  batchGetSessions(params: BatchGetSessionsRequest): Promise<BatchGetSessionsResponse>;
  subscribeSessionList(params: ListSubscribeRequest): Promise<ListSubscribeResponse>;
  unsubscribeSessionList(params: ListUnsubscribeRequest): Promise<EmptyResponse>;
  renameSessionTitle(params: RenameSessionRequest): Promise<EmptyResponse>;
@@ -455,10 +468,15 @@ type SessionIndexMethods = {
  unarchiveSession(params: SessionIdRequest): Promise<EmptyResponse>;
 };

-/** Routes `_session/list/subscribe`, `_session/list/unsubscribe`,
+/** Routes `_session/batch_get`, `_session/list/subscribe`, `_session/list/unsubscribe`,
 *  `_session/rename`, `_session/archive` and `_session/unarchive`. */
 export function onSessionIndexRequests(app: AgentApp, agent: () => SessionIndexMethods): AgentApp {
  return app
+    .onRequest<BatchGetSessionsRequest, BatchGetSessionsResponse>(
+      SESSION_BATCH_GET_METHOD,
+      { parse: parseBatchGetSessionsRequest },
+      (ctx) => agent().batchGetSessions(ctx.params),
+    )
    .onRequest<ListSubscribeRequest, ListSubscribeResponse>(
      LIST_SUBSCRIBE_METHOD,
      { parse: parseListSubscribeRequest },
--- a/src/session-index/project-dirs.ts
+++ b/src/session-index/project-dirs.ts
@@ -104,6 +104,17 @@ export async function canonicalPath(cwd: string): Promise<string> {
  }
 }

+/** Whether the path exists, including a symlink whose target is missing. */
+export async function exists(target: string): Promise<boolean> {
+  try {
+    await fs.lstat(target);
+    return true;
+  } catch (error) {
+    if (errorCode(error) === "ENOENT" || errorCode(error) === "ENOTDIR") return false;
+    throw error;
+  }
+}
+
 /** The names of the project directories of `cwd` among `rootEntries`. */
 export function projectDirsOf(cwd: string, rootEntries: readonly string[]): string[] {
  const exact = encodeProjectPath(cwd);
--- a/src/session-index/service.ts
+++ b/src/session-index/service.ts
@@ -15,6 +15,7 @@ import {
  RequestError,
  type ListSessionsRequest,
  type ListSessionsResponse,
+  type SessionInfo,
 } from "@agentclientprotocol/sdk/unstable";
 import { deleteSession as sdkDeleteSession } from "@anthropic-ai/claude-agent-sdk";
 import { airExtensionMeta } from "../air-extension.js";
@@ -37,7 +38,7 @@ import {
 import { LiveSessionRegistry } from "./live-registry.js";
 import {
  canonicalPath,
-  errorCode,
+  exists,
  isExactProjectDir,
  isSessionId,
  projectDirMatches,
@@ -65,6 +66,7 @@ import { sessionInfoOf } from "./session-info.js";
 export const SESSION_RENAME_METHOD = "_session/rename";
 export const SESSION_ARCHIVE_METHOD = "_session/archive";
 export const SESSION_UNARCHIVE_METHOD = "_session/unarchive";
+export const SESSION_BATCH_GET_METHOD = "_session/batch_get";

 /** The JSON-RPC code of an unknown session (ACP `ResourceNotFound`). */
 const RESOURCE_NOT_FOUND = -32002;
@@ -73,6 +75,27 @@ const CURSOR_VERSION = 5;

 export type SessionIdRequest = { sessionId: string };
 export type RenameSessionRequest = { sessionId: string; title: string };
+export type BatchGetSessionsRequest = { sessionIds: string[] };
+export type BatchGetSessionsResponse = {
+  sessions: SessionInfo[];
+};
+
+export function parseBatchGetSessionsRequest(value: unknown): BatchGetSessionsRequest {
+  const record = asRecord(value);
+  const ids = record.sessionIds;
+  if (
+    Object.keys(record).length !== 1 ||
+    !Array.isArray(ids) ||
+    ids.some((id) => typeof id !== "string" || !id.trim()) ||
+    new Set(ids).size !== ids.length
+  ) {
+    throw RequestError.invalidParams(
+      undefined,
+      "params require only sessionIds: distinct, non-blank strings",
+    );
+  }
+  return { sessionIds: ids };
+}

 export function sessionNotFound(sessionId: string): RequestError {
  return new RequestError(RESOURCE_NOT_FOUND, `Session not found: ${sessionId}`, { sessionId });
@@ -364,16 +387,6 @@ function isSdkNotFound(error: unknown): boolean {
  return error instanceof Error && /^Session \S+ not found in /.test(error.message);
 }

-async function exists(target: string): Promise<boolean> {
-  try {
-    await fs.lstat(target);
-    return true;
-  } catch (error) {
-    if (errorCode(error) === "ENOENT" || errorCode(error) === "ENOTDIR") return false;
-    throw error;
-  }
-}
-
 /** The error the SDK `deleteSession` gives for a session id it rejects or
 *  does not find, which a client without `sessionIndex` got before. */
 function sdkDeleteError(sessionId: string): Error {
@@ -520,6 +533,22 @@ export class SessionIndexService {
    return hasMore && last ? { sessions, nextCursor: encodeListCursor(last, scope) } : { sessions };
  }

+  /** Metadata for known ids, independent of list pages and project filters. */
+  async batchGet(
+    { sessionIds }: BatchGetSessionsRequest,
+    own: (sessionId: string) => OwnSessionState | undefined,
+  ): Promise<BatchGetSessionsResponse> {
+    if (sessionIds.length === 0) return { sessions: [] };
+    const live = await this.registry.snapshot();
+    const now = this.now();
+    const rows = await this.index.getSessions(sessionIds);
+    return {
+      sessions: rows.map((row) =>
+        sessionInfoOf(row, own(row.sessionId), live.get(row.sessionId), now),
+      ),
+    };
+  }
+
  /** Runs `mutation` after the previous mutation of the session ended. */
  private exclusive<T>(sessionId: string, mutation: () => Promise<T>): Promise<T> {
    const previous = this.mutations.get(sessionId) ?? Promise.resolve();
--- a/src/session-index/session-index.ts
+++ b/src/session-index/session-index.ts
@@ -26,6 +26,8 @@ import { effectiveTitle, visibleTitle } from "./archive-title.js";
 import {
  canonicalPath,
  encodeProjectPath,
+  errorCode,
+  exists,
  isExactProjectDir,
  isSessionId,
  normalizePath,
@@ -58,11 +60,15 @@ import { isInLinkedWorktree, worktreeCounterparts } from "./worktrees.js";

 export const DEFAULT_LIST_LIMIT = 50;
 export const MAX_LIST_LIMIT = 200;
+/** Discovery could not establish which sessions the store contains. */
+export class SessionStoreUnavailableError extends Error {}
 /** Entries of the metadata cache: a few hundred bytes each, so the
 *  transcripts of a large history (tens of thousands) stay cached and deep
 *  pages do not read them again. */
 const METADATA_CACHE_SIZE = 50_000;
 const READ_BATCH_SIZE = 16;
+/** Session ids looked up together by {@link SessionIndex.getSessions}. */
+const LOOKUP_CHUNK_SIZE = 100;
 /** Transcripts read at most per directory to recover a sibling's cwd. */
 const MAX_CWD_PROBES_PER_DIR = 64;
 /** How long a directory that gave no cwd is not probed again. */
@@ -97,6 +103,24 @@ export type TranscriptCandidate = {
  ino: number;
 };

+type TranscriptFile = Pick<
+  TranscriptCandidate,
+  "sessionId" | "filePath" | "dirName" | "projectPath"
+>;
+
+/** Non-empty transcript files, with bounded stats shared by lists and id lookups. */
+async function transcriptCandidates(
+  files: readonly TranscriptFile[],
+): Promise<TranscriptCandidate[]> {
+  const stats = await statFiles(files.map(({ filePath }) => filePath));
+  return files.flatMap((file, i) => {
+    const current = stats[i];
+    return current?.isFile() && current.size > 0
+      ? [{ ...file, mtimeMs: current.mtimeMs, size: current.size, ino: current.ino }]
+      : [];
+  });
+}
+
 /** The cached metadata of one transcript. */
 type TranscriptMetadata = {
  /** The visible title: without the archive prefix. */
@@ -526,25 +550,16 @@ export class SessionIndex {
    const listed = await this.listings.namesOfAll(dirPaths);
    const files = dirs.flatMap(({ dirName, projectPath }, i) =>
      listed[i]!.filter((name) => name.endsWith(".jsonl") && isSessionId(name.slice(0, -6))).map(
-        (name) => ({ name, filePath: path.join(root, dirName, name), dirName, projectPath }),
+        (name) => ({
+          sessionId: name.slice(0, -6),
+          filePath: path.join(root, dirName, name),
+          dirName,
+          projectPath,
+        }),
      ),
    );
-    const stats = await statFiles(files.map(({ filePath }) => filePath));
-    const all: TranscriptCandidate[] = [];
-    files.forEach(({ name, filePath, dirName, projectPath }, i) => {
-      const fileStats = stats[i];
-      if (!fileStats?.isFile() || fileStats.size === 0) return;
-      all.push({
-        sessionId: name.slice(0, -6),
-        filePath,
-        dirName,
-        projectPath,
-        mtimeMs: fileStats.mtimeMs,
-        size: fileStats.size,
-        ino: fileStats.ino,
-      });
-    });
-    return { dirs: [root, ...dirPaths], names: [rootNames, ...listed], candidates: all };
+    const candidates = await transcriptCandidates(files);
+    return { dirs: [root, ...dirPaths], names: [rootNames, ...listed], candidates };
  }

  /**
@@ -580,6 +595,90 @@ export class SessionIndex {
    };
  }

+  /** Known ids in request order, using the same rows as the list.
+   *  Addresses exact filenames; only rows without a cwd need sibling discovery. */
+  async getSessions(sessionIds: readonly string[]): Promise<IndexRow[]> {
+    if (sessionIds.length === 0) return [];
+    const root = projectsRoot();
+    let projectEntries: string[];
+    try {
+      projectEntries = await fs.readdir(root);
+    } catch (cause) {
+      if (errorCode(cause) === "ENOENT" && !(await exists(root))) {
+        return [];
+      }
+      throw new SessionStoreUnavailableError("Session store could not be read", { cause });
+    }
+    const ids = sessionIds.filter(isSessionId);
+    const byId = new Map<string, IndexRow>();
+    // Paths are project directories × ids: bound them per chunk, not per request.
+    for (let start = 0; start < ids.length; start += LOOKUP_CHUNK_SIZE) {
+      const chunk = ids.slice(start, start + LOOKUP_CHUNK_SIZE);
+      for (const row of await this.lookupRows(root, projectEntries, chunk)) {
+        byId.set(row.sessionId, row);
+      }
+    }
+    return sessionIds.flatMap((id) => {
+      const row = byId.get(id);
+      return row ? [row] : [];
+    });
+  }
+
+  /** The rows of `ids` found under `projectEntries`. All copies of an id are
+   *  in the same call, so copy selection is unchanged by chunking. */
+  private async lookupRows(
+    root: string,
+    projectEntries: readonly string[],
+    ids: readonly string[],
+  ): Promise<IndexRow[]> {
+    let candidates = await transcriptCandidates(
+      projectEntries.flatMap((dirName) =>
+        ids.map((sessionId) => ({
+          sessionId,
+          filePath: path.join(root, dirName, `${sessionId}.jsonl`),
+          dirName,
+        })),
+      ),
+    );
+    if (CASE_INSENSITIVE_PATHS) {
+      // On a case-insensitive file system, stat of `ABC.jsonl` also finds
+      // `abc.jsonl`. Keep a file only when its real name is the requested one,
+      // or differs by more than case (a symlink, as the list would read it).
+      // A failed realpath means the file is unreadable, so the id is omitted.
+      const exact = await Promise.all(
+        candidates.map(async ({ filePath }) => {
+          try {
+            const actual = path.basename(await fs.realpath(filePath));
+            const expected = path.basename(filePath);
+            return actual === expected || actual.toLowerCase() !== expected.toLowerCase();
+          } catch {
+            return false;
+          }
+        }),
+      );
+      candidates = candidates.filter((_, i) => exact[i]);
+    }
+    return this.collectRows(candidates.sort(byMtimeDescending), {
+      inScope: scopeOf(undefined),
+      archived: "all",
+      wanted: Infinity,
+      unread: async (read, dirNames) => {
+        const dirs = [...dirNames];
+        const listed = await this.listings.namesOfAll(dirs.map((dir) => path.join(root, dir)));
+        const siblings = dirs.flatMap((dirName, i) =>
+          listed[i]!.filter((name) => name.endsWith(".jsonl") && isSessionId(name.slice(0, -6)))
+            .map((name) => ({
+              sessionId: name.slice(0, -6),
+              filePath: path.join(root, dirName, name),
+              dirName,
+            }))
+            .filter(({ filePath }) => !read.has(filePath)),
+        );
+        return (await transcriptCandidates(siblings)).sort(byMtimeDescending);
+      },
+    });
+  }
+
  /** Every transcript file of `sessionId` (see {@link scanSession}). Empty
   *  files only with `includeEmpty`. */
  async findTranscripts(
@@ -778,9 +877,12 @@ export class SessionIndex {
      archived: ArchivedFilter;
      after?: ListCursor;
      wanted: number;
-      /** The transcripts not read (by path), which may supply a sibling's
-       *  cwd. */
-      unread: (read: ReadonlySet<string>) => readonly TranscriptCandidate[];
+      /** The unread transcripts of the directories still eligible for cwd
+       *  recovery. Called only after checking the negative cache. */
+      unread?: (
+        read: ReadonlySet<string>,
+        dirNames: ReadonlySet<string>,
+      ) => readonly TranscriptCandidate[] | Promise<readonly TranscriptCandidate[]>;
      restat?: boolean;
    },
  ): Promise<IndexRow[]> {
@@ -852,14 +954,15 @@ export class SessionIndex {
      }
      await settlePending();
    }
-    if (pending.length > 0) {
+    const unread = options.unread;
+    if (pending.length > 0 && unread) {
      // A row recovered after the scan stopped still sorts into the page: it
      // was read before the stop, and more rows only raise the bound. A
      // sibling that the archive filter or the cursor leaves out may still
      // supply the cwd.
      await this.learnDirCwds(
        new Set(pending.map(({ candidate }) => candidate.dirName)),
-        options.unread(read),
+        (dirNames) => unread(read, dirNames),
        options.restat ?? false,
      );
      await settlePending();
@@ -893,7 +996,9 @@ export class SessionIndex {
   *  changes. `restat` as in {@link collectRows}. */
  private async learnDirCwds(
    dirNames: ReadonlySet<string>,
-    unread: readonly TranscriptCandidate[],
+    unread: (
+      dirNames: ReadonlySet<string>,
+    ) => readonly TranscriptCandidate[] | Promise<readonly TranscriptCandidate[]>,
    restatFirst: boolean,
  ): Promise<void> {
    const root = projectsRoot();
@@ -909,8 +1014,9 @@ export class SessionIndex {
      if (known && known.mtimeMs === mtimeMs && now - known.at < NO_CWD_RETRY_MS) continue;
      mtimes.set(dirName, mtimeMs);
    }
+    if (mtimes.size === 0) return;
    const probes = new Map<string, number>();
-    let remaining = unread.filter((candidate) => {
+    let remaining = (await unread(new Set(mtimes.keys()))).filter((candidate) => {
      if (!mtimes.has(candidate.dirName)) return false;
      const count = probes.get(candidate.dirName) ?? 0;
      if (count >= MAX_CWD_PROBES_PER_DIR) return false;
--- a/src/session-model.ts
+++ b/src/session-model.ts
@@ -595,12 +595,20 @@ export async function getAvailableModels(
  for (const name of displayNames) {
    displayNameCounts.set(name, (displayNameCounts.get(name) ?? 0) + 1);
  }
+  const names = models.map((model, index) =>
+    displayNameCounts.get(displayNames[index]) === 1 ? displayNames[index] : model.displayName,
+  );
+  const nameCounts = new Map<string, number>();
+  for (const name of names) {
+    nameCounts.set(name, (nameCounts.get(name) ?? 0) + 1);
+  }

  return {
    availableModels: models.map((model, index) => ({
      modelId: model.value,
-      name:
-        displayNameCounts.get(displayNames[index]) === 1 ? displayNames[index] : model.displayName,
+      // Allowlisted aliases can inherit the same SDK label. Keep every ID
+      // selectable, but distinguish the rows for clients that show only names.
+      name: nameCounts.get(names[index]) === 1 ? names[index] : `${names[index]} (${model.value})`,
      description: model.description,
    })),
    currentModelId: currentModel.value,
--- a/src/session-ultracode.ts
+++ b/src/session-ultracode.ts
@@ -0,0 +1,136 @@
+import type {
+  SessionConfigOption,
+  SetSessionConfigOptionRequest,
+} from "@agentclientprotocol/sdk/unstable";
+import type { ModelInfo, Query } from "@anthropic-ai/claude-agent-sdk";
+import { ULTRACODE_CONFIG_ID } from "./session-config-ids.js";
+
+export { ULTRACODE_CONFIG_ID } from "./session-config-ids.js";
+
+/** Select-fallback values for clients without boolean config options. */
+export const ULTRACODE_ON = "on";
+export const ULTRACODE_OFF = "off";
+const ULTRACODE_DESCRIPTION = "Dynamic workflows on every task, at any effort level";
+
+/** Ultracode state from the CLI's `get_settings` control response
+ *  (`applied.ultracodeAvailable` / `applied.ultracodeRequested`). Each field is
+ *  undefined when the CLI does not report it. */
+export type UltracodeSettingsReport = {
+  /** Workflows are enabled and the current model supports ultracode. */
+  available?: boolean;
+  /** Ultracode is turned on for the session, whether or not it can take
+   *  effect on the current model. */
+  requested?: boolean;
+};
+
+// `Query.getSettings()` exists at runtime (sdk.mjs) but is missing from the
+// SDK's type declarations as of 0.3.310.
+type GetSettingsQuery = Query & {
+  getSettings?: () => Promise<{
+    applied?: { ultracodeAvailable?: unknown; ultracodeRequested?: unknown };
+  }>;
+};
+
+/** Ask the CLI whether ultracode is available and requested for the session.
+ *  Returns undefined when the SDK has no `getSettings` or the request fails;
+ *  callers then fall back to {@link modelSupportsUltracode}. */
+export async function readUltracodeSettings(
+  query: Query,
+): Promise<UltracodeSettingsReport | undefined> {
+  const getSettings = (query as GetSettingsQuery).getSettings;
+  if (typeof getSettings !== "function") return undefined;
+  try {
+    const applied = (await getSettings.call(query))?.applied;
+    return {
+      available:
+        typeof applied?.ultracodeAvailable === "boolean" ? applied.ultracodeAvailable : undefined,
+      requested:
+        typeof applied?.ultracodeRequested === "boolean" ? applied.ultracodeRequested : undefined,
+    };
+  } catch {
+    return undefined;
+  }
+}
+
+/** The CLI supports ultracode on exactly the models that support `xhigh`
+ *  effort (both use the same capability check), and `supportedEffortLevels`
+ *  lists `xhigh` only for those models. E.g. Opus 4.7+, Sonnet 5+ and Haiku
+ *  5.5 qualify; Opus 4.6 and Haiku 4.5 do not. */
+export function modelSupportsUltracode(modelInfo: ModelInfo | undefined): boolean {
+  return (
+    modelInfo?.supportsEffort === true &&
+    modelInfo.supportedEffortLevels?.includes("xhigh") === true
+  );
+}
+
+/** Whether dynamic workflows are enabled for the session, inferred from the
+ *  CLI's `ultracodeAvailable` for the model the session started on. This is
+ *  the part of availability that does not change with the model: the plan
+ *  default (off on Pro), `enableWorkflows`/`disableWorkflows` and org policy.
+ *  Undefined when the report can't tell, e.g. `ultracodeAvailable: false` on a
+ *  model that lacks ultracode support anyway. */
+export function ultracodeWorkflowsEnabled(
+  report: UltracodeSettingsReport | undefined,
+  modelInfo: ModelInfo | undefined,
+): boolean | undefined {
+  if (report?.available === true) return true;
+  if (report?.available === false && modelSupportsUltracode(modelInfo)) return false;
+  return undefined;
+}
+
+/** Whether to offer the ultracode toggle for `modelInfo`. An unknown workflows
+ *  state shows the toggle: the CLI keeps an unavailable request without
+ *  error, so the toggle is merely inert there. */
+export function ultracodeSupported(
+  workflowsEnabled: boolean | undefined,
+  modelInfo: ModelInfo | undefined,
+): boolean {
+  return workflowsEnabled !== false && modelSupportsUltracode(modelInfo);
+}
+
+/** Ultracode state threaded into `buildConfigOptions`. The option is only
+ *  surfaced while `supported`. */
+export type UltracodeOptionState = {
+  supported: boolean;
+  enabled: boolean;
+  /** Whether the client opted into boolean config options. */
+  useBooleanOption: boolean;
+};
+
+/** Build the ultracode toggle: a native boolean for clients that opted into
+ *  boolean config options, otherwise an "on"/"off" select. */
+export function createUltracodeConfigOption(
+  enabled: boolean,
+  useBooleanOption: boolean,
+): SessionConfigOption {
+  const base = {
+    id: ULTRACODE_CONFIG_ID,
+    name: "Ultracode",
+    description: ULTRACODE_DESCRIPTION,
+    category: "model_config",
+  } as const;
+
+  if (useBooleanOption) {
+    return { ...base, type: "boolean", currentValue: enabled };
+  }
+
+  return {
+    ...base,
+    type: "select",
+    currentValue: enabled ? ULTRACODE_ON : ULTRACODE_OFF,
+    options: [
+      { value: ULTRACODE_ON, name: "On" },
+      { value: ULTRACODE_OFF, name: "Off" },
+    ],
+  };
+}
+
+/** Read the requested ultracode value from a `session/set_config_option`
+ *  request: a boolean, or the "on"/"off" select-fallback strings. */
+export function resolveUltracodeEnabled(params: SetSessionConfigOptionRequest): boolean {
+  const value = params.value;
+  if (typeof value === "boolean") return value;
+  if (value === ULTRACODE_ON) return true;
+  if (value === ULTRACODE_OFF) return false;
+  throw new Error(`Invalid value for config option ${ULTRACODE_CONFIG_ID}: ${value}`);
+}
--- a/src/subagent-replay.ts
+++ b/src/subagent-replay.ts
@@ -112,6 +112,12 @@ export class RfdSubagentReplay {
    private readonly history: SubagentHistory,
    private readonly publish: Publish,
    private readonly models?: SubagentModels,
+    /**
+     * Whether the replay maps a model to the session's model list as it goes.
+     * A load lacks the list until the CLI started, so it maps only in
+     * {@link currentStates}, after the load response.
+     */
+    private readonly mapsDuringReplay = true,
  ) {}

  /**
@@ -189,7 +195,7 @@ export class RfdSubagentReplay {
   * whose model changes gets its `model` option again.
   */
  async responseModel(owner: ReplayChild, model: string | undefined): Promise<void> {
-    const entry = responseModelEntry(model, this.models);
+    const entry = responseModelEntry(model, this.mapsDuringReplay ? this.models : undefined);
    if (!entry || !owner.announced) return;
    owner.responseModel = model;
    await this.sendModel(owner, entry);
--- a/src/tests/acp-agent.test.ts
+++ b/src/tests/acp-agent.test.ts
@@ -3596,11 +3596,19 @@ describe("subagent transcript replay", () => {
      { log: () => {}, error: () => {} },
    );
    await initializeClient(agent, AIR_NATIVE_SUBAGENTS);
-    vi.mocked(getSessionMessages).mockResolvedValueOnce(replayHistory);
    // A load replays while the CLI starts: the session and its model list come later.
    await (
-      agent as unknown as { replaySessionHistory(sessionId: string): Promise<void> }
-    ).replaySessionHistory("s1");
+      agent as unknown as {
+        replaySessionHistory(
+          sessionId: string,
+          messages: unknown[],
+          pending: unknown,
+        ): Promise<void>;
+      }
+    ).replaySessionHistory("s1", replayHistory, {
+      state: { cwd: "/tmp", taskState: new Map(), messageIdToUuid: new Map() },
+      stopped: false,
+    });
    const child = "s1:replay-subagent:parent-agent-call";
    const models = () =>
      updates.flatMap(({ sessionId, update }) =>
@@ -3877,7 +3885,14 @@ describe("subagent transcript replay", () => {
        /** The session's config options and model list, known after the response. */
        models?: { configOptions: SessionConfigOption[]; modelInfos: ModelInfo[] };
      },
-      { traceModels = false }: { traceModels?: boolean } = {},
+      {
+        traceModels = false,
+        load = false,
+      }: {
+        traceModels?: boolean;
+        /** Replay as a load does, while the CLI starts: without the session record. */
+        load?: boolean;
+      } = {},
    ): Promise<string[]> {
      const configDir = await mkdtemp(path.join(os.tmpdir(), "claude-acp-rfd-replay-"));
      const originalConfigDir = process.env.CLAUDE_CONFIG_DIR;
@@ -3915,9 +3930,21 @@ describe("subagent transcript replay", () => {
        );
        await initializeClient(agent, capabilities);
        vi.mocked(getSessionInfo).mockResolvedValueOnce({ cwd: "/tmp/proj" } as any);
+        const pending = load
+          ? {
+              state: { cwd: "/tmp/proj", taskState: new Map(), messageIdToUuid: new Map() },
+              stopped: false,
+            }
+          : undefined;
        await (
-          agent as unknown as { replaySessionHistory(sessionId: string): Promise<void> }
-        ).replaySessionHistory(sessionId);
+          agent as unknown as {
+            replaySessionHistory(
+              sessionId: string,
+              messages?: unknown[],
+              pending?: unknown,
+            ): Promise<void>;
+          }
+        ).replaySessionHistory(sessionId, undefined, pending);
        const responseAt = updates.length;
        if (afterResponse) {
          // Stands in for the live session's runtime, which knows its running children.
@@ -4268,7 +4295,7 @@ describe("subagent transcript replay", () => {
            ],
          },
        },
-        { traceModels: true },
+        { traceModels: true, load: true },
      );

      const opus = JSON.stringify([{ value: "opus", name: "Opus 5" }]);
@@ -12604,6 +12631,56 @@ describe("stop reason propagation", () => {
    expect((err as { data: unknown }).data).toEqual({ errorKind: "rate_limit" });
  });

+  it.each(
+    [false, true].flatMap((typedFailures) =>
+      [undefined, "authentication_failed" as const].map((staleError) => ({
+        typedFailures,
+        staleError,
+      })),
+    ),
+  )(
+    "preserves a usage-limit failure after compaction (typed: $typedFailures, stale error: $staleError)",
+    async ({ typedFailures, staleError }) => {
+      const agent = createMockAgent();
+      if (typedFailures) await initializeClient(agent, airSessionFailureCapabilities);
+      const staleFrame = createAssistantError(staleError, "stale compaction output");
+      staleFrame.message.model = "<synthetic>";
+      injectSession(agent, [
+        {
+          type: "system",
+          subtype: "status",
+          status: null,
+          compact_result: "success",
+          uuid: "compact-completed",
+          session_id: "test-session",
+        },
+        createUsageLimitAssistantError(),
+        staleFrame,
+        createResultMessage({
+          subtype: "success",
+          stop_reason: "end_turn",
+          is_error: true,
+          result: "private provider detail",
+        }),
+      ]);
+
+      const prompt = agent.prompt({
+        sessionId: "test-session",
+        prompt: [{ type: "text", text: "test" }],
+      });
+      if (typedFailures) {
+        expect(sessionFailureFromResponse(await prompt)).toMatchObject({
+          category: "limit",
+          actions: [],
+          title:
+            "You've hit your individual spend limit · run /usage-credits to ask your admin for a higher limit",
+        });
+      } else {
+        await expect(prompt).rejects.toMatchObject({ data: { errorKind: "rate_limit" } });
+      }
+    },
+  );
+
  it("omits errorKind data when no SDKAssistantMessage.error was observed", async () => {
    const agent = createMockAgent();
    injectSession(agent, [
@@ -13901,6 +13978,7 @@ describe("session/close", () => {
      agents: [],
      currentAgent: "default",
      fastModeEnabled: false,
+      ultracodeEnabled: false,
      abortController: new AbortController(),
      emitRawSDKMessages: false,
      forwardSubagentText: false,
@@ -14022,6 +14100,7 @@ describe("session/delete", () => {
      agents: [],
      currentAgent: "default",
      fastModeEnabled: false,
+      ultracodeEnabled: false,
      abortController: new AbortController(),
      emitRawSDKMessages: false,
      forwardSubagentText: false,
@@ -14181,6 +14260,7 @@ describe("getOrCreateSession param change detection", () => {
      agents: [],
      currentAgent: "default",
      fastModeEnabled: false,
+      ultracodeEnabled: false,
      abortController: new AbortController(),
      emitRawSDKMessages: false,
      forwardSubagentText: false,
@@ -15937,6 +16017,132 @@ describe("usage_update computation", () => {
  });
 });

+describe("foreground fork tool results", () => {
+  it.each([
+    ["plain", {}, null],
+    ["AIR", AIR_CLIENT_CAPABILITIES, null],
+    ["plain nested", {}, "toolu_outer"],
+    ["AIR nested", AIR_CLIENT_CAPABILITIES, "toolu_outer"],
+  ] as const)(
+    "waits for the launching side's result for a %s client",
+    async (_, capabilities, parent) => {
+      const updates: SessionNotification[] = [];
+      const logger = { log: vi.fn(), error: vi.fn() };
+      const agent = new ClaudeAcpAgent(
+        {
+          sessionUpdate: async (notification: SessionNotification) => {
+            updates.push(notification);
+          },
+        } as unknown as AcpClient,
+        logger,
+      );
+      await initializeClient(agent, capabilities);
+      const input = new Pushable<any>();
+      const assistant = (content: unknown[], parentToolUseId: string | null) => ({
+        type: "assistant",
+        parent_tool_use_id: parentToolUseId,
+        uuid: randomUUID(),
+        session_id: "test-session",
+        message: {
+          id: randomUUID(),
+          role: "assistant",
+          model: "claude-sonnet-4-6",
+          content,
+          usage: successfulResultMessage().usage,
+        },
+      });
+      const user = (content: unknown[], parentToolUseId: string | null) => ({
+        type: "user",
+        parent_tool_use_id: parentToolUseId,
+        uuid: randomUUID(),
+        session_id: "test-session",
+        message: { role: "user", content },
+      });
+      const toolResult = (id: string, text: string) => ({
+        type: "tool_result",
+        tool_use_id: id,
+        content: [{ type: "text", text }],
+      });
+      async function* messages() {
+        const { value } = await input[Symbol.asyncIterator]().next();
+        yield userEcho(value);
+        yield assistant(
+          [
+            {
+              type: "tool_use",
+              id: "toolu_fork",
+              name: "Agent",
+              input: {
+                subagent_type: "fork",
+                run_in_background: false,
+                prompt: "Inspect the parser",
+              },
+            },
+          ],
+          parent,
+        );
+        // The fork inherits a result for its own launch. It cannot complete
+        // that call: the launching side sends the actual report later.
+        yield user([toolResult("toolu_fork", "Fork started — that fork is you.")], "toolu_fork");
+        yield assistant(
+          [
+            {
+              type: "tool_use",
+              id: "toolu_child",
+              name: "Agent",
+              input: { subagent_type: "general-purpose", prompt: "Read the parser" },
+            },
+          ],
+          "toolu_fork",
+        );
+        // Keep results of tools the fork itself called, even in a message
+        // that also carries the copied launch result.
+        yield {
+          ...user(
+            [
+              toolResult("toolu_fork", "Fork started — processing in background"),
+              toolResult("toolu_child", "child report"),
+            ],
+            "toolu_fork",
+          ),
+          // Filtering must not attribute the inherited launch sidecar to
+          // the one result that remains in this message.
+          tool_use_result: {
+            status: "completed",
+            content: [{ type: "text", text: "inherited launch report" }],
+          },
+        };
+        yield user([toolResult("toolu_fork", "fork report")], parent);
+        yield successfulResultMessage();
+        yield { type: "system", subtype: "session_state_changed", state: "idle" };
+      }
+      agent.sessions["test-session"] = mockSessionState({ query: wrapQuery(messages()), input });
+
+      await expect(
+        agent.prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "Inspect it" }] }),
+      ).resolves.toMatchObject({ stopReason: "end_turn" });
+
+      const completed = updates.flatMap(({ update }) =>
+        update.sessionUpdate === "tool_call_update" && update.status === "completed"
+          ? [{ id: update.toolCallId, content: update.content, rawOutput: update.rawOutput }]
+          : [],
+      );
+      expect(completed.map(({ id }) => id)).toEqual(["toolu_child", "toolu_fork"]);
+      expect(completed.map(({ content }) => content)).toEqual([
+        [{ type: "content", content: { type: "text", text: "child report" } }],
+        [{ type: "content", content: { type: "text", text: "fork report" } }],
+      ]);
+      if (!("_meta" in capabilities)) {
+        expect(completed.map(({ rawOutput }) => rawOutput)).toEqual([
+          [{ type: "text", text: "child report" }],
+          [{ type: "text", text: "fork report" }],
+        ]);
+      }
+      expect(logger.error.mock.calls.flat().join("\n")).not.toContain("wasn't tracked");
+    },
+  );
+});
+
 describe("assembled assistant text fallback", () => {
  const ZERO_USAGE = {
    input_tokens: 0,
@@ -18509,6 +18715,7 @@ describe("post-error recovery", () => {
      agents: [],
      currentAgent: "default",
      fastModeEnabled: false,
+      ultracodeEnabled: false,
      abortController: new AbortController(),
      emitRawSDKMessages: false,
      forwardSubagentText: false,
@@ -26865,6 +27072,7 @@ describe("session/cancel wedge recovery (issue #680)", () => {
      agents: [],
      currentAgent: "default",
      fastModeEnabled: false,
+      ultracodeEnabled: false,
      abortController: new AbortController(),
      emitRawSDKMessages: false,
      forwardSubagentText: false,
@@ -28772,6 +28980,7 @@ describe("agent selection config option", () => {
        agents,
        currentAgent: "default",
        fastModeEnabled: false,
+        ultracodeEnabled: false,
        abortController: new AbortController(),
        emitRawSDKMessages: false,
        forwardSubagentText: false,
--- a/src/tests/acp-v2.test.ts
+++ b/src/tests/acp-v2.test.ts
@@ -153,7 +153,7 @@ afterEach(async () => {
  await Promise.all(agents.splice(0).map((agent) => agent.dispose()));
  execFileSpy.mockReset();
  vi.unstubAllEnvs();
-  await rm(tempDir, { recursive: true, force: true });
+  await rm(tempDir, { recursive: true, force: true, maxRetries: 10 });
 });

 /** Connects a fresh router to a client, and returns the client end of the stream. */
--- a/src/tests/auth-status.test.ts
+++ b/src/tests/auth-status.test.ts
@@ -22,6 +22,11 @@ vi.mock("@anthropic-ai/claude-agent-sdk", async () => ({
 /** Shared spy for both `claude auth status --json` and `claude auth logout`.
 *  Tests set `execFileResults` per invoked subcommand. */
 const execFileSpy = vi.hoisted(() => vi.fn());
+/** `auth status` probes, wherever global options such as `--settings` put the subcommand. */
+function isStatusProbe(args: string[]): boolean {
+  const auth = args.indexOf("auth");
+  return auth >= 0 && args[auth + 1] === "status";
+}

 vi.mock("node:child_process", async () => {
  const actual = await vi.importActual<typeof import("node:child_process")>("node:child_process");
@@ -409,7 +414,7 @@ describe("auth status over ACP", () => {
    execFileSpy.mockImplementation((...invocation: unknown[]) => {
      const args = invocation[1] as string[];
      const cb = invocation[invocation.length - 1] as (...a: unknown[]) => void;
-      if (args[1] === "status") {
+      if (isStatusProbe(args)) {
        const stdout = statusStdout;
        const fails = statusFails;
        const answer = () => {
@@ -451,7 +456,7 @@ describe("auth status over ACP", () => {
  });

  function statusCalls() {
-    return execFileSpy.mock.calls.filter((call) => (call[1] as string[])[1] === "status");
+    return execFileSpy.mock.calls.filter((call) => isStatusProbe(call[1] as string[]));
  }

  function updates() {
@@ -542,11 +547,11 @@ describe("auth status over ACP", () => {
      env: { ANTHROPIC_BASE_URL: "https://example.invalid/override" },
    });
    expect(statusCalls().at(-1)?.[1]).toEqual([
+      "--settings",
+      JSON.stringify({ apiKeyHelper: "central proxy start" }),
      "auth",
      "status",
      "--json",
-      "--settings",
-      JSON.stringify({ apiKeyHelper: "central proxy start" }),
    ]);
    await promptOnce(sessionId);
    await flushStatus();
--- a/src/tests/clear-context-coordinator.test.ts
+++ b/src/tests/clear-context-coordinator.test.ts
@@ -31,6 +31,7 @@ function testSession(overrides: Partial<TestSession> = {}): TestSession {
    configOptions: [],
    currentAgent: "default",
    fastModeEnabled: false,
+    ultracodeEnabled: false,
    input: { push: vi.fn() },
    ...overrides,
  };
@@ -49,6 +50,7 @@ function testHost(
      return freshSession;
    }),
    applyFastMode: vi.fn(async () => {}),
+    applyUltracode: vi.fn(async () => {}),
    publishSessionState: vi.fn(async () => {}),
    continuationMessage: vi.fn((sessionId, plan, promptUuid) => ({
      type: "user" as const,
@@ -252,6 +254,25 @@ describe("continuePlanInFreshContext", () => {
    expect(host.applyFastMode).toHaveBeenCalledWith(freshSession, false);
  });

+  it("restores ultracode turned on before clearing context", async () => {
+    const turn: ClearContextTurn = {
+      settled: false,
+      promptUuid: "00000000-0000-4000-8000-000000000000",
+    };
+    const oldSession = testSession({ activeTurn: turn, ultracodeEnabled: true });
+    const freshSession = testSession({ ultracodeEnabled: false });
+    const host = testHost(oldSession, freshSession);
+
+    await continuePlanInFreshContext(
+      "public-session",
+      oldSession,
+      { toolUseId: "tool-plan", plan: "Ship it", mode: "auto" },
+      host,
+    );
+
+    expect(host.applyUltracode).toHaveBeenCalledWith(freshSession, true);
+  });
+
  it("does not publish or continue a restart cancelled while creating the fresh session", async () => {
    const turn: ClearContextTurn = {
      settled: false,
--- a/src/tests/folded-steer.test.ts
+++ b/src/tests/folded-steer.test.ts
@@ -0,0 +1,298 @@
+import { describe, expect, it, vi } from "vitest";
+import { randomUUID } from "node:crypto";
+import { ClaudeAcpAgent, type AcpClient } from "../acp-agent.js";
+import { Pushable } from "../utils.js";
+import {
+  mockSessionState,
+  successfulResultMessage,
+  userEcho,
+  wrapQuery,
+} from "./session-doubles.js";
+
+vi.mock("@anthropic-ai/claude-agent-sdk", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@anthropic-ai/claude-agent-sdk")>();
+  const refused = () => {
+    throw new Error("Unexpected real SDK call");
+  };
+  return {
+    ...actual,
+    query: vi.fn(refused),
+    getSessionMessages: vi.fn(async () => []),
+    getSubagentMessages: vi.fn(async () => []),
+    listSessions: vi.fn(async () => []),
+    getSessionInfo: vi.fn(async () => undefined),
+    deleteSession: vi.fn(refused),
+    forkSession: vi.fn(refused),
+    importSessionToStore: vi.fn(refused),
+  };
+});
+
+async function untilDone<T>(promise: Promise<T>): Promise<T> {
+  let timer: ReturnType<typeof setTimeout> | undefined;
+  try {
+    return await Promise.race([
+      promise,
+      new Promise<never>((_, reject) => {
+        timer = setTimeout(() => reject(new Error("Prompt did not settle")), 3000);
+      }),
+    ]);
+  } finally {
+    if (timer !== undefined) clearTimeout(timer);
+  }
+}
+
+function createAgent() {
+  const client = { sessionUpdate: async () => {} } as unknown as AcpClient;
+  return new ClaudeAcpAgent(client, { log: () => {}, error: () => {} });
+}
+
+function usage(inputTokens: number, outputTokens: number) {
+  return {
+    input_tokens: inputTokens,
+    output_tokens: outputTokens,
+    cache_read_input_tokens: 0,
+    cache_creation_input_tokens: 0,
+  };
+}
+
+function modelUsage(inputTokens: number, outputTokens: number) {
+  return {
+    "claude-sonnet-4-6": {
+      inputTokens,
+      outputTokens,
+      cacheReadInputTokens: 0,
+      cacheCreationInputTokens: 0,
+      webSearchRequests: 0,
+      costUSD: 0,
+      contextWindow: 200000,
+    },
+  };
+}
+
+function stamp(uuid: string, fields: string) {
+  return {
+    ...(fields !== "plural" ? { user_message_uuid: uuid } : {}),
+    ...(fields !== "singular" ? { user_message_uuids: [uuid] } : {}),
+  };
+}
+
+const idle = { type: "system", subtype: "session_state_changed", state: "idle" };
+
+describe("a steer folded into an autonomous cycle", () => {
+  it.each([
+    ["singular", true],
+    ["plural", true],
+    ["both", true],
+    ["singular", false],
+    ["plural", false],
+    ["both", false],
+  ] as const)("settles from its own %s UUID stamp (echo: %s)", async (fields, echo) => {
+    const agent = createAgent();
+    const input = new Pushable<any>();
+    const echoed = Promise.withResolvers<void>();
+    const interrupted = Promise.withResolvers<void>();
+    const resume = Promise.withResolvers<void>();
+    const processed = Promise.withResolvers<void>();
+    const finish = Promise.withResolvers<void>();
+    async function* messages() {
+      const iter = input[Symbol.asyncIterator]();
+      const { value: original } = await iter.next();
+      yield userEcho(original);
+      echoed.resolve();
+      const { value: steered } = await iter.next();
+      yield successfulResultMessage({
+        origin: { kind: "human" },
+        ...stamp(original.uuid, "both"),
+        queued_turn_count: 1,
+        stop_reason: "tool_use",
+        usage: usage(10, 5),
+        modelUsage: modelUsage(10, 5),
+      });
+      interrupted.resolve();
+      await resume.promise;
+      if (echo) yield userEcho(steered);
+      // Only the steer's UUID is named; it has no queued Turn of its own.
+      yield successfulResultMessage({
+        origin: { kind: "task-notification" },
+        ...stamp(steered.uuid, fields),
+        queued_turn_count: 0,
+        stop_reason: "max_tokens",
+        usage: usage(20, 7),
+        modelUsage: modelUsage(30, 12),
+      });
+      yield idle;
+      processed.resolve();
+      // Stream shutdown must not supply the prompt's response.
+      await finish.promise;
+    }
+    const session = mockSessionState({ input, query: wrapQuery(messages()) });
+    agent.sessions["test-session"] = session;
+    let response: unknown;
+    const prompt = agent
+      .prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "original" }] })
+      .then((value) => (response = value));
+    try {
+      await untilDone(echoed.promise);
+      await expect(
+        agent.steer({
+          sessionId: "test-session",
+          prompt: [{ type: "text", text: "also handle this" }],
+        }),
+      ).resolves.toEqual({ outcome: "injected" });
+      await untilDone(interrupted.promise);
+      expect(response).toBeUndefined();
+      resume.resolve();
+      await untilDone(processed.promise);
+      await untilDone(prompt);
+      const tokenCount = {
+        totalTokens: 42,
+        inputTokens: 30,
+        cachedInputTokens: 0,
+        cachedWriteTokens: 0,
+        outputTokens: 12,
+        reasoningOutputTokens: 0,
+      };
+      expect(response).toEqual({
+        stopReason: "max_tokens",
+        usage: {
+          inputTokens: 30,
+          outputTokens: 12,
+          cachedReadTokens: 0,
+          cachedWriteTokens: 0,
+          totalTokens: 42,
+        },
+        _meta: {
+          quota: {
+            token_count: tokenCount,
+            model_usage: [{ model: "claude-sonnet-4-6", token_count: tokenCount }],
+          },
+        },
+      });
+      expect(session.activeTurn).toBeNull();
+      expect(session.turnQueue).toHaveLength(0);
+      expect(session.owedTrailingIdles).toBe(0);
+    } finally {
+      resume.resolve();
+      finish.resolve();
+      await untilDone(session.consumer);
+      await untilDone(prompt);
+    }
+  });
+
+  it.each(["unrelated", "held", "settled", "plural-unrelated", "plural-empty"] as const)(
+    "does not attribute a result to a steer in the %s state",
+    async (state) => {
+      const agent = createAgent();
+      const input = new Pushable<any>();
+      const echoed = Promise.withResolvers<void>();
+      const processed = Promise.withResolvers<void>();
+      const resume = Promise.withResolvers<void>();
+      const finish = Promise.withResolvers<void>();
+      let response: unknown;
+      let owner: any;
+      let steerUuid = "";
+      const heldOutcome = { stopReason: "end_turn" };
+      async function* messages() {
+        const iter = input[Symbol.asyncIterator]();
+        const { value: original } = await iter.next();
+        yield userEcho(original);
+        echoed.resolve();
+        const { value: steered } = await iter.next();
+        steerUuid = steered.uuid;
+        const session = agent.sessions["test-session"];
+        owner = session.activeTurn;
+        // Constructed defensive states: these do not model normal settlement.
+        if (state === "held") {
+          owner.deferredSettle = heldOutcome;
+          owner.spawnedTaskIds = new Set(["still-running"]);
+          session.liveBackgroundTasks.set("still-running", { isSubagent: true });
+        } else if (state === "settled") {
+          owner.settled = true;
+        }
+        const unrelated = randomUUID();
+        yield successfulResultMessage({
+          origin: { kind: "task-notification" },
+          user_message_uuid: state === "unrelated" ? unrelated : steerUuid,
+          user_message_uuids:
+            state === "plural-empty" ? [] : [state.includes("unrelated") ? unrelated : steerUuid],
+          stop_reason: "refusal",
+          usage: usage(100, 50),
+          modelUsage: modelUsage(100, 50),
+        });
+        processed.resolve();
+        await resume.promise;
+        owner.settled = false;
+        owner.deferredSettle = undefined;
+        owner.spawnedTaskIds = undefined;
+        session.liveBackgroundTasks.clear();
+        yield successfulResultMessage({
+          origin: { kind: "human" },
+          ...stamp(steerUuid, "both"),
+          usage: usage(10, 5),
+        });
+        yield idle; // the excluded autonomous result's trailer
+        yield idle; // the human result's trailer
+        await finish.promise;
+      }
+      const session = mockSessionState({ input, query: wrapQuery(messages()) });
+      agent.sessions["test-session"] = session;
+      const prompt = agent
+        .prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "original" }] })
+        .then((value) => (response = value));
+      try {
+        await untilDone(echoed.promise);
+        await expect(
+          agent.steer({
+            sessionId: "test-session",
+            prompt: [{ type: "text", text: "also handle this" }],
+          }),
+        ).resolves.toEqual({ outcome: "injected" });
+        await untilDone(processed.promise);
+        expect(response).toBeUndefined();
+        expect(session.activeTurn).toBe(owner);
+        expect(session.accumulatedUsage).toEqual({
+          inputTokens: 0,
+          outputTokens: 0,
+          cachedReadTokens: 0,
+          cachedWriteTokens: 0,
+        });
+        expect(session.accumulatedModelUsage).toEqual({});
+        expect(owner.steeredUuids).toEqual(new Set([steerUuid]));
+        expect(owner.steeredEchoes).toEqual(new Set([steerUuid]));
+        expect(owner.steeredSettle).toBeUndefined();
+        if (state === "held") expect(owner.deferredSettle).toBe(heldOutcome);
+        if (state === "settled") expect(owner.settled).toBe(true);
+        resume.resolve();
+        await untilDone(prompt);
+        expect(response).toEqual({
+          stopReason: "end_turn",
+          usage: {
+            inputTokens: 10,
+            outputTokens: 5,
+            cachedReadTokens: 0,
+            cachedWriteTokens: 0,
+            totalTokens: 15,
+          },
+          _meta: {
+            quota: {
+              token_count: {
+                totalTokens: 15,
+                inputTokens: 10,
+                cachedInputTokens: 0,
+                cachedWriteTokens: 0,
+                outputTokens: 5,
+                reasoningOutputTokens: 0,
+              },
+              model_usage: [],
+            },
+          },
+        });
+      } finally {
+        resume.resolve();
+        finish.resolve();
+        await untilDone(session.consumer);
+        await untilDone(prompt);
+      }
+    },
+  );
+});
--- a/src/tests/helpers.ts
+++ b/src/tests/helpers.ts
@@ -31,6 +31,9 @@ export function makeMockQuery(overrides: Record<string, unknown> = {}) {
    supportedCommands: async () => [],
    mcpServerStatus: async () => [],
    getContextUsage: async () => DEFAULT_CONTEXT_USAGE,
+    // No ultracode fields: session creation falls back to settings and the
+    // model's effort levels, as with a CLI that does not report them.
+    getSettings: async () => ({ applied: {} }),
    close: () => {},
    interrupt: async () => undefined,
    [Symbol.asyncIterator]: async function* () {},
--- a/src/tests/incomplete-tools.test.ts
+++ b/src/tests/incomplete-tools.test.ts
@@ -97,6 +97,76 @@ describe("incomplete foreground tools", () => {
    expect(agent.sessions[sessionId].toolCallParents?.size ?? 0).toBe(0);
  });

+  it.each([
+    {
+      content: { type: "advisor_result", text: "Check the queue ordering." },
+      status: "completed",
+      text: "Check the queue ordering.",
+    },
+    {
+      content: { type: "advisor_redacted_result", encrypted_content: "opaque-advice" },
+      status: "completed",
+      text: "Advisor guidance applied server-side.",
+    },
+    {
+      content: { type: "advisor_tool_result_error", error_code: "overloaded" },
+      status: "failed",
+      text: "Advisor error: overloaded",
+    },
+  ] as const)(
+    "settles an advisor call with a $content.type result",
+    async ({ content, status, text }) => {
+      const advisorId = "srvtoolu_advisor";
+      const { prompt, updates, logError, agent } = createTestSession(async function* (input) {
+        yield* echoNextPrompt(input);
+        yield advisorStart(advisorId);
+        yield advisorToolUse(advisorId);
+        yield advisorResult(advisorId, content);
+        expect(hasHookCallback(advisorId)).toBe(false);
+        yield successfulResultMessage();
+      });
+
+      await expect(prompt()).resolves.toMatchObject({ stopReason: "end_turn" });
+      const terminal = updates.filter(
+        (update) =>
+          update.toolCallId === advisorId &&
+          (update.status === "completed" || update.status === "failed"),
+      );
+      expect(terminal).toHaveLength(1);
+      expect(terminal[0]).toMatchObject({
+        sessionUpdate: "tool_call_update",
+        toolCallId: advisorId,
+        status,
+      });
+      expect(JSON.stringify(terminal[0])).toContain(text);
+      expect(JSON.stringify(updates)).not.toContain("opaque-advice");
+      expect(agent.sessions[sessionId].emittedToolCalls.has(advisorId)).toBe(false);
+      expect(agent.sessions[sessionId].dispatchedToolCalls?.has(advisorId)).toBe(false);
+      expect(logError).not.toHaveBeenCalled();
+    },
+  );
+
+  it("fails a dispatched advisor call without a result", async () => {
+    const advisorId = "srvtoolu_advisor";
+    const { prompt, updates, agent } = createTestSession(async function* (input) {
+      yield* echoNextPrompt(input);
+      yield advisorStart(advisorId);
+      yield advisorToolUse(advisorId);
+      yield successfulResultMessage();
+    });
+
+    await expect(prompt()).rejects.toMatchObject({ data: { errorKind: "incomplete_tool_call" } });
+    const terminal = updates.filter(
+      (update) =>
+        update.toolCallId === advisorId &&
+        (update.status === "completed" || update.status === "failed"),
+    );
+    expect(terminal).toHaveLength(1);
+    expect(terminal[0]).toMatchObject({ status: "failed" });
+    expect(agent.sessions[sessionId].emittedToolCalls.has(advisorId)).toBe(false);
+    expect(agent.sessions[sessionId].dispatchedToolCalls?.has(advisorId)).toBe(false);
+  });
+
  it("allows a tool explicitly handed off to a background task", async () => {
    const { prompt, updates } = createTestSession(backgroundToolMessages);

@@ -1123,6 +1193,44 @@ function toolUse(
  };
 }

+function advisorStart(id: string) {
+  return {
+    ...toolStart(id),
+    event: {
+      type: "content_block_start",
+      index: 0,
+      content_block: { type: "server_tool_use", id, name: "advisor", input: {} },
+    },
+  };
+}
+
+/** The complete assistant message that dispatches the advisor server tool. */
+function advisorToolUse(id: string) {
+  return {
+    type: "assistant",
+    session_id: sessionId,
+    parent_tool_use_id: null,
+    message: {
+      role: "assistant",
+      usage: successfulResultMessage().usage,
+      content: [{ type: "server_tool_use", id, name: "advisor", input: {} }],
+    },
+  };
+}
+
+function advisorResult(id: string, content: unknown) {
+  return {
+    type: "assistant",
+    session_id: sessionId,
+    parent_tool_use_id: null,
+    message: {
+      role: "assistant",
+      usage: successfulResultMessage().usage,
+      content: [{ type: "advisor_tool_result", tool_use_id: id, content }],
+    },
+  };
+}
+
 function assistantText(text: string) {
  return {
    type: "assistant",
--- a/src/tests/model-presentation.test.ts
+++ b/src/tests/model-presentation.test.ts
@@ -1,6 +1,10 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { query, type ModelInfo, type Query } from "@anthropic-ai/claude-agent-sdk";
-import { buildModelConfigOption, getAvailableModels } from "../session-model.js";
+import {
+  applyAvailableModelsAllowlist,
+  buildModelConfigOption,
+  getAvailableModels,
+} from "../session-model.js";

 const OPUS: ModelInfo = {
  value: "opus[1m]",
@@ -151,6 +155,68 @@ describe("versioned model display names", () => {
    );
    expect(state.availableModels.map((model) => model.name)).toEqual(["Opus (1M context)", "Opus"]);
  });
+
+  it("distinguishes allowlisted aliases and pins that inherit the same SDK label", async () => {
+    const sdkModels: ModelInfo[] = [
+      { value: "default", displayName: "Default (recommended)", description: "" },
+      {
+        value: "opus",
+        resolvedModel: "claude-opus-5-5",
+        displayName: "Opus 5.5",
+        description: "For complex work and everyday tasks",
+      },
+      { value: "haiku", displayName: "Haiku", description: "Fast" },
+    ];
+    const ids = ["claude-opus-5-5[1m]", "claude-opus-5-5", "opus[1m]", "opus", "haiku"];
+    const models = applyAvailableModelsAllowlist(sdkModels, ids);
+    const setModel = vi.fn();
+    const state = await getAvailableModels(
+      { setModel } as unknown as Query,
+      models,
+      sdkModels,
+      { getSettings: () => ({}) },
+      { log: vi.fn(), error: vi.fn() },
+      false,
+      "model-presentation-test",
+    );
+
+    const expected = [
+      "Default (recommended)",
+      ...ids.slice(0, 4).map((id) => `Opus 5.5 (${id})`),
+      "Haiku",
+    ];
+    expect(state.availableModels.map((model) => model.name)).toEqual(expected);
+    expect(state.availableModels.map((model) => model.modelId)).toEqual(["default", ...ids]);
+    expect(state.currentModelId).toBe("default");
+    expect(state.availableModels.slice(1, 5).map((model) => model.description)).toEqual(
+      Array(4).fill(sdkModels[1].description),
+    );
+    const option = buildModelConfigOption(state, models, false);
+    expect(option).toMatchObject({ currentValue: "default" });
+    expect(option.type === "select" && option.options.map((model) => model.name)).toEqual(expected);
+    expect(sdkModels[1].displayName).toBe("Opus 5.5");
+    expect(setModel).not.toHaveBeenCalled();
+  });
+
+  it("distinguishes identical custom labels without changing their model IDs", async () => {
+    const models: ModelInfo[] = [
+      { value: "provider-a", displayName: "My model", description: "First endpoint" },
+      { value: "provider-b", displayName: "My model", description: "Second endpoint" },
+    ];
+    const state = await getAvailableModels(
+      {} as Query,
+      models,
+      models,
+      { getSettings: () => ({}) },
+      { log: vi.fn(), error: vi.fn() },
+      false,
+      "model-presentation-test",
+    );
+    expect(state.availableModels).toEqual([
+      { modelId: "provider-a", name: "My model (provider-a)", description: "First endpoint" },
+      { modelId: "provider-b", name: "My model (provider-b)", description: "Second endpoint" },
+    ]);
+  });
 });

 // Account-dependent model availability requires the same authenticated environment
@@ -172,19 +238,18 @@ it.skipIf(!process.env.RUN_INTEGRATION_TESTS)(
    const q = query({ prompt: input(), options: { persistSession: false, abortController } });
    try {
      const { models } = await q.initializationResult();
-      const opusModels = models.filter(
-        (model) =>
-          model.value !== "default" &&
-          /\bopus\b/i.test(`${model.value} ${model.resolvedModel} ${model.displayName}`),
-      );
+      // Only alias rows ("opus", "opus[1m]"). The catalogue also lists pinned
+      // older versions such as "claude-opus-4-8"; those are separate models.
+      const opusModels = models.filter((model) => /^opus\b/i.test(model.value));
      expect(opusModels).toHaveLength(1);
      // CLI 2.1.283 dropped the "[1m]" / "(1M context)" spelling from the Opus
      // row: Opus is natively 1M, so the row names the plain model.
      expect(opusModels[0]).toMatchObject({
        value: "opus",
-        displayName: "Opus",
+        displayName: expect.stringMatching(/^Opus\b/),
        resolvedModel: expect.stringMatching(/^claude-opus-[\d-]+$/),
      });
+      expect(opusModels[0].displayName).not.toMatch(/\b1m\b/i);
      expect(opusModels[0].description).not.toMatch(/\b1m\b/i);
    } finally {
      clearTimeout(timeout);
--- a/src/tests/model-resolution.test.ts
+++ b/src/tests/model-resolution.test.ts
@@ -381,17 +381,17 @@ describe("settingsEffortForModel", () => {
 });

 describe("effortFlagSettings", () => {
-  it("carries ultracode only when settings request it", () => {
-    expect(effortFlagSettings("high", { ultracode: true })).toEqual({
+  it("carries ultracode only while the session has it on", () => {
+    expect(effortFlagSettings("high", true)).toEqual({
      effortLevel: "high",
      ultracode: true,
    });
-    expect(effortFlagSettings("default", { ultracode: true })).toEqual({
+    expect(effortFlagSettings("default", true)).toEqual({
      effortLevel: null,
      ultracode: true,
    });
-    expect(effortFlagSettings("high", { ultracode: false })).toEqual({ effortLevel: "high" });
-    expect(effortFlagSettings(undefined, {})).toEqual({ effortLevel: null });
+    expect(effortFlagSettings("high", false)).toEqual({ effortLevel: "high" });
+    expect(effortFlagSettings(undefined, false)).toEqual({ effortLevel: null });
  });
 });

--- a/src/tests/native-subagents.test.ts
+++ b/src/tests/native-subagents.test.ts
@@ -2678,6 +2678,44 @@ describe("NativeSubagentRuntime child models", () => {
    },
  );

+  it.each(["rfd", "air"] as const)(
+    "%s: sends a model again after its publication failed",
+    async (form) => {
+      const published: AcpSessionNotification[] = [];
+      let failures = 1;
+      const runtime = new NativeSubagentRuntime(
+        form,
+        "root",
+        {},
+        async (notification) => {
+          if (notification.update.sessionUpdate === "config_option_update" && failures-- > 0) {
+            throw new Error("client gone");
+          }
+          published.push(notification);
+        },
+        { log: () => {} },
+        undefined,
+        undefined,
+        models,
+      );
+      const deliver = async (notification: AcpSessionNotification) => {
+        const routed = await runtime.route(notification, deliver);
+        if (routed) published.push(routed);
+      };
+      await deliver(agentCall("launch-1", {}));
+      await runtime.taskStarted(
+        { taskId: "worker-1", toolUseId: "launch-1", subagentType: "Explore" },
+        deliver,
+      );
+      await expect(runtime.reportModel("launch-1", "claude-sonnet-4-6", deliver)).rejects.toThrow(
+        "client gone",
+      );
+      expect(modelUpdates(published)).toEqual([]);
+      await runtime.reportModel("launch-1", "claude-sonnet-4-6", deliver);
+      expect(modelUpdates(published)).toEqual([["worker-1", "sonnet", "Sonnet 4.6"]]);
+    },
+  );
+
  it("air: forgets the configuration of an ended child", async () => {
    const { runtime, published, deliver } = await spawn("air");
    await runtime.reportModel("launch-1", "claude-sonnet-4-6", deliver);
--- a/src/tests/session-index.test.ts
+++ b/src/tests/session-index.test.ts
@@ -16,13 +16,18 @@ import {
  listSessions,
 } from "@anthropic-ai/claude-agent-sdk";
 import { spawn } from "node:child_process";
-import { ClaudeAcpAgent, type AcpClient } from "../acp-agent.js";
-import type { SessionInfo } from "@agentclientprotocol/sdk/unstable";
+import { ClaudeAcpAgent, v1AgentApp, type AcpClient } from "../acp-agent.js";
+import {
+  client as acpClient,
+  type InitializeResponse,
+  type SessionInfo,
+} from "@agentclientprotocol/sdk/unstable";
 import { encodeProjectPath } from "../session-index/project-dirs.js";
 import {
  archiveInsteadOfDelete,
  archiveTo,
  renameTo,
+  parseBatchGetSessionsRequest,
  SessionIndexService,
  writeCustomTitleSidecar,
 } from "../session-index/service.js";
@@ -45,6 +50,11 @@ import {
 } from "./session-doubles.js";
 import { Pushable } from "../utils.js";

+vi.mock("node:fs/promises", async (importOriginal) => {
+  const actual = await importOriginal<typeof fs>();
+  return { ...actual, readdir: vi.fn(actual.readdir) };
+});
+
 vi.mock("@anthropic-ai/claude-agent-sdk", async (importOriginal) => {
  const actual = await importOriginal<typeof import("@anthropic-ai/claude-agent-sdk")>();
  return {
@@ -69,10 +79,15 @@ beforeEach(async () => {
  configDir = fsSync.realpathSync(await fs.mkdtemp(path.join(os.tmpdir(), "session-index-cfg-")));
  workspace = fsSync.realpathSync(await fs.mkdtemp(path.join(os.tmpdir(), "session-index-ws-")));
  process.env.CLAUDE_CONFIG_DIR = configDir;
+  // Integration runs leave CLAUDE_CODE_EXECUTABLE unset, so initialize would run
+  // the real `claude auth status` in the background. It writes into configDir
+  // while afterEach removes it, and the rm fails with ENOTEMPTY.
+  vi.stubEnv("CLAUDE_CODE_EXECUTABLE", "/usr/bin/false");
  vi.clearAllMocks();
 });

 afterEach(async () => {
+  vi.unstubAllEnvs();
  if (previousConfigDir === undefined) delete process.env.CLAUDE_CONFIG_DIR;
  else process.env.CLAUDE_CONFIG_DIR = previousConfigDir;
  await fs.rm(configDir, { recursive: true, force: true });
@@ -257,6 +272,7 @@ const airCapabilities = (response: { _meta?: Record<string, unknown> | null }) =
 describe("sessionIndex negotiation", () => {
  const indexCapabilities = [
    "sessionIndex",
+    "sessionBatchGet",
    "sessionArchive",
    "sessionRename",
    "sessionListSubscribe",
@@ -290,7 +306,7 @@ describe("sessionIndex negotiation", () => {
    // Declaring archive or rename alone enables nothing.
    const withoutIndex = await createAgent().agent.initialize({
      protocolVersion: 1,
-      clientCapabilities: air("sessionArchive", "sessionRename"),
+      clientCapabilities: air("sessionArchive", "sessionRename", "sessionBatchGet"),
    });
    expect(airCapabilities(withoutIndex)).toEqual(baseline);

@@ -314,7 +330,7 @@ describe("sessionIndex negotiation", () => {
  it("answers method-not-found to the new methods without the capability", async () => {
    // Declaring sessionArchive or sessionRename without sessionIndex enables
    // nothing either.
-    for (const capabilities of [[], ["sessionArchive", "sessionRename"]]) {
+    for (const capabilities of [[], ["sessionArchive", "sessionRename", "sessionBatchGet"]]) {
      const { agent } = createAgent();
      await initializeClient(agent, air(...capabilities));
      const sessionId = randomUUID();
@@ -323,10 +339,423 @@ describe("sessionIndex negotiation", () => {
      });
      await expect(agent.archiveSession({ sessionId })).rejects.toMatchObject({ code: -32601 });
      await expect(agent.unarchiveSession({ sessionId })).rejects.toMatchObject({ code: -32601 });
+      await expect(agent.batchGetSessions({ sessionIds: [sessionId] })).rejects.toMatchObject({
+        code: -32601,
+      });
    }
  });
 });

+describe("_session/batch_get", () => {
+  it("routes and validates the extension through the ACP connection", async () => {
+    let agent!: ClaudeAcpAgent;
+    const connection = acpClient({ name: "batch-get-test" }).connect(
+      v1AgentApp({ log: () => {}, error: () => {} }, (created) => {
+        agent = created;
+      }),
+    );
+    try {
+      const response = await connection.agent.request<InitializeResponse>("initialize", {
+        protocolVersion: 1,
+        clientCapabilities: air("sessionIndex"),
+      });
+      expect(airCapabilities(response)).toContain("sessionBatchGet");
+      expect(await connection.agent.request("_session/batch_get", { sessionIds: [] })).toEqual({
+        sessions: [],
+      });
+      await expect(
+        connection.agent.request("_session/batch_get", { sessionIds: [], cwd: "/repo" }),
+      ).rejects.toMatchObject({ code: -32602 });
+    } finally {
+      connection.close();
+      await agent.dispose();
+    }
+  });
+
+  it("accepts only distinct, non-blank string ids and no other fields", () => {
+    for (const params of [
+      null,
+      [],
+      {},
+      { sessionIds: null },
+      { sessionIds: "id" },
+      { sessionIds: [""] },
+      { sessionIds: [" "] },
+      { sessionIds: [1] },
+      { sessionIds: ["id", "id"] },
+      { sessionIds: [], cwd: null },
+    ]) {
+      expect(() => parseBatchGetSessionsRequest(params)).toThrow(
+        expect.objectContaining({ code: -32602 }),
+      );
+    }
+    const sessionIds = Array.from({ length: 1000 }, (_, i) => `id-${i}`);
+    expect(parseBatchGetSessionsRequest({ sessionIds })).toEqual({ sessionIds });
+    // Ids are exact, not trimmed or otherwise normalized.
+    expect(parseBatchGetSessionsRequest({ sessionIds: [" id ", "id"] })).toEqual({
+      sessionIds: [" id ", "id"],
+    });
+  });
+
+  it("returns empty results without touching the store", async () => {
+    const { agent } = await indexAgent();
+    const index = (agent as any).sessionIndex.service.index;
+    const lookup = vi.spyOn(index, "getSessions").mockRejectedValue(new Error("store down"));
+    expect(await agent.batchGetSessions({ sessionIds: [] })).toEqual({
+      sessions: [],
+    });
+    expect(lookup).not.toHaveBeenCalled();
+    await agent.dispose();
+  });
+
+  it("returns no sessions when the store is absent", async () => {
+    const { agent } = await indexAgent();
+    const sessionIds = [randomUUID(), "retained-id"];
+    expect(await agent.batchGetSessions({ sessionIds })).toEqual({
+      sessions: [],
+    });
+    await agent.dispose();
+  });
+
+  it("finds ids older than the recent 50 without listing or reading unrelated history", async () => {
+    const base = Date.parse("2026-03-01T00:00:00Z");
+    const ids: string[] = [];
+    for (let i = 0; i < 55; i++) {
+      ids.push(
+        (
+          await writeTranscript({
+            cwd: path.join(workspace, `project-${i % 2}`),
+            lastMessageAt: base - i * 60_000,
+          })
+        ).id,
+      );
+    }
+    const recent = await indexAgent();
+    const page = await recent.agent.listSessions({});
+    expect(page.sessions).toHaveLength(50);
+    expect(page.sessions.map((s) => s.sessionId)).not.toContain(ids[54]);
+    await recent.agent.dispose();
+    const { agent } = await indexAgent();
+    const index = (agent as any).sessionIndex.service.index;
+    const list = vi.spyOn(index, "list").mockRejectedValue(new Error("must not list"));
+    const names = vi.spyOn(index.listings, "namesOfAll").mockRejectedValue(new Error("history"));
+    const wanted = [ids[54]!, ids[53]!, ids[0]!];
+    const readdir = vi.mocked(fs.readdir);
+    readdir.mockClear();
+    try {
+      const result = await agent.batchGetSessions({ sessionIds: wanted });
+      expect(result.sessions.map((s) => s.sessionId)).toEqual(wanted);
+      expect(transcriptsRead(agent)).toBe(wanted.length);
+      const root = path.join(configDir, "projects");
+      const storeReads = readdir.mock.calls
+        .map(([dir]) => String(dir))
+        .filter((dir) => dir === root || dir.startsWith(root + path.sep));
+      expect(storeReads).toEqual([root]);
+      expect(list).not.toHaveBeenCalled();
+      expect(names).not.toHaveBeenCalled();
+      expect(listSessions).not.toHaveBeenCalled();
+      expect(getSessionInfo).not.toHaveBeenCalled();
+    } finally {
+      readdir.mockClear();
+      await agent.dispose();
+    }
+  });
+
+  it("keeps request order and copy selection across lookup chunks", async () => {
+    const base = Date.parse("2026-03-01T00:00:00Z");
+    const first = await writeTranscript({ lastMessageAt: base });
+    const last = await writeTranscript({ lastMessageAt: base - 60_000 });
+    const copyId = randomUUID();
+    await writeTranscript({ sessionId: copyId, prompt: "Old copy", lastMessageAt: base - 120_000 });
+    await writeTranscript({
+      sessionId: copyId,
+      cwd: path.join(workspace, "other"),
+      prompt: "New copy",
+      lastMessageAt: base - 30_000,
+    });
+    // 250 ids: three lookup chunks of 100, with found ids in the first, second and third.
+    const sessionIds: string[] = Array.from({ length: 250 }, () => randomUUID());
+    sessionIds[0] = last.id;
+    sessionIds[120] = copyId;
+    sessionIds[249] = first.id;
+    const { agent } = await indexAgent();
+    try {
+      const result = await agent.batchGetSessions({ sessionIds });
+      expect(result.sessions.map((s) => s.sessionId)).toEqual([last.id, copyId, first.id]);
+      expect(result.sessions[1]!.title).toBe("New copy");
+    } finally {
+      await agent.dispose();
+    }
+  });
+
+  it("recovers a cold batch row from a sibling and keeps it in the next list", async () => {
+    const base = Date.parse("2026-04-01T00:00:00Z");
+    const other = path.join(workspace, "other");
+    const noCwd = await writeTranscript({ cwd: other, recordCwd: null, lastMessageAt: base });
+    const fillers: string[] = [];
+    for (let i = 1; i <= 16; i++) {
+      fillers.push((await writeTranscript({ lastMessageAt: base - i * 1000 })).id);
+    }
+    // This sibling is older than the transcripts needed to fill the page.
+    await writeTranscript({ cwd: other, lastMessageAt: base - 3600_000 });
+    const { agent } = await indexAgent();
+    const index = (agent as any).sessionIndex.service.index;
+    const names = vi.spyOn(index.listings, "namesOfAll");
+    const now = vi.spyOn(Date, "now").mockReturnValue(Date.now());
+    try {
+      const result = await agent.batchGetSessions({ sessionIds: [noCwd.id] });
+      expect(result.sessions.map((s) => [s.sessionId, s.cwd])).toEqual([[noCwd.id, other]]);
+      expect(transcriptsRead(agent)).toBe(2);
+      expect(names.mock.calls).toEqual([[[path.dirname(noCwd.file)]]]);
+      names.mockRestore();
+
+      // Use the same index without changing files or letting the negative cache expire.
+      const page = await agent.listSessions({ _meta: listMeta({ limit: 2 }) });
+      expect(page.sessions.map((s) => [s.sessionId, s.cwd])).toEqual([
+        [noCwd.id, other],
+        [fillers[0], workspace],
+      ]);
+      expect(page.sessions[0]).toEqual(result.sessions[0]);
+    } finally {
+      names.mockRestore();
+      now.mockRestore();
+      await agent.dispose();
+    }
+  });
+
+  it("bounds sibling cwd probes and retries a negative result after its cache expires", async () => {
+    const base = Date.parse("2026-04-01T00:00:00Z");
+    const other = path.join(workspace, "other");
+    const noCwd = await writeTranscript({ cwd: other, recordCwd: null, lastMessageAt: base });
+    const siblings: { id: string; file: string }[] = [];
+    for (let i = 1; i <= 70; i++) {
+      siblings.push(
+        await writeTranscript({ cwd: other, recordCwd: null, lastMessageAt: base - i * 1000 }),
+      );
+    }
+    await writeTranscript({ lastMessageAt: base });
+    const { agent } = await indexAgent();
+    const index = (agent as any).sessionIndex.service.index;
+    const names = vi.spyOn(index.listings, "namesOfAll");
+    const at = Date.now();
+    const now = vi.spyOn(Date, "now").mockReturnValue(at);
+    try {
+      expect(await agent.batchGetSessions({ sessionIds: [noCwd.id] })).toEqual({ sessions: [] });
+      expect(transcriptsRead(agent)).toBe(1 + 64);
+      expect(names.mock.calls).toEqual([[[path.dirname(noCwd.file)]]]);
+
+      // Rewriting an existing sibling does not change the directory mtime.
+      await writeTranscript({ sessionId: siblings[0]!.id, cwd: other, lastMessageAt: base });
+      expect(await agent.batchGetSessions({ sessionIds: [noCwd.id] })).toEqual({ sessions: [] });
+      expect(transcriptsRead(agent)).toBe(1 + 64);
+      expect(names).toHaveBeenCalledTimes(1);
+
+      now.mockReturnValue(at + 60_001);
+      const result = await agent.batchGetSessions({ sessionIds: [noCwd.id] });
+      expect(result.sessions.map((s) => [s.sessionId, s.cwd])).toEqual([[noCwd.id, other]]);
+      expect(transcriptsRead(agent)).toBe(1 + 64 + 1);
+      expect(names.mock.calls).toEqual([
+        [[path.dirname(noCwd.file)]],
+        [[path.dirname(noCwd.file)]],
+      ]);
+    } finally {
+      names.mockRestore();
+      now.mockRestore();
+      await agent.dispose();
+    }
+  });
+
+  it("returns the same unscoped list rows for archived, worktree and duplicate copies in request order", async () => {
+    const repo = path.join(workspace, "repo");
+    const worktree = path.join(workspace, "worktree");
+    await linkWorktrees(repo, worktree);
+    const archivedId = randomUUID();
+    const archived = await writeTranscript({
+      sessionId: archivedId,
+      cwd: repo,
+      trailer: titleRecords(archivedId, "[archived] Done"),
+    });
+    const worktreeId = randomUUID();
+    await writeTranscript({
+      sessionId: worktreeId,
+      cwd: worktree,
+      trailer: [worktreeState(worktreeId, { path: worktree })],
+    });
+    const copyId = randomUUID();
+    await writeTranscript({ sessionId: copyId, cwd: repo, prompt: "Old copy" });
+    await writeTranscript({
+      sessionId: copyId,
+      cwd: worktree,
+      prompt: "New copy",
+      mtimeMs: Date.parse("2026-02-01"),
+    });
+    const { agent } = await indexAgent();
+    const requested = [worktreeId, archived.id, copyId];
+    const result = await agent.batchGetSessions({ sessionIds: requested });
+    const read = transcriptsRead(agent);
+    const listed = await agent.listSessions({ _meta: listMeta({ archived: "all" }) });
+    expect(transcriptsRead(agent)).toBe(read);
+    expect(result.sessions).toEqual(
+      requested.map((id) => listed.sessions.find((s) => s.sessionId === id)),
+    );
+    expect(airRow(result.sessions[1]!).archived).toBe(true);
+    expect(agentWorktreeOfRow(result.sessions[0])).toBe(true);
+    expect(result.sessions[2]).toMatchObject({ title: "New copy", cwd: worktree });
+    await agent.dispose();
+  });
+
+  it.skipIf(process.platform === "win32" || process.getuid?.() === 0)(
+    "returns readable sessions in request order and omits unavailable ids",
+    async () => {
+      const first = await writeTranscript({});
+      const found = await writeTranscript({});
+      const unreadable = await writeTranscript({});
+      await fs.chmod(unreadable.file, 0);
+      const absent = randomUUID();
+      const { agent } = await indexAgent();
+      try {
+        const result = await agent.batchGetSessions({
+          sessionIds: [absent, first.id, unreadable.id, found.id],
+        });
+        expect(result.sessions.map((s) => s.sessionId)).toEqual([first.id, found.id]);
+        expect(Object.keys(result)).toEqual(["sessions"]);
+      } finally {
+        await fs.chmod(unreadable.file, 0o600);
+        await agent.dispose();
+      }
+    },
+  );
+
+  it.skipIf(process.platform === "win32" || process.getuid?.() === 0)(
+    "uses a readable copy when another copy cannot be read or stat'ed, as the unscoped list does",
+    async () => {
+      const sessionId = randomUUID();
+      await writeTranscript({ sessionId, prompt: "Readable copy" });
+      const hiddenProject = path.join(workspace, "inaccessible");
+      const unreadable = await writeTranscript({
+        sessionId,
+        cwd: hiddenProject,
+        prompt: "Unreadable newer copy",
+        mtimeMs: Date.parse("2026-02-01"),
+      });
+      const { agent } = await indexAgent();
+      try {
+        // A failed metadata read, then a failed stat of the same copy.
+        for (const target of [unreadable.file, path.dirname(unreadable.file)]) {
+          await fs.chmod(target, 0);
+          const result = await agent.batchGetSessions({ sessionIds: [sessionId] });
+          const listed = await agent.listSessions({});
+          expect(result).toEqual({ sessions: listed.sessions });
+          expect(result.sessions[0]?.title).toBe("Readable copy");
+          await fs.chmod(target, 0o700);
+        }
+      } finally {
+        await fs.chmod(path.dirname(unreadable.file), 0o700);
+        await fs.chmod(unreadable.file, 0o600);
+        await agent.dispose();
+      }
+    },
+  );
+
+  it.skipIf(process.platform === "win32" || process.getuid?.() === 0)(
+    "omits failed stats, dangling links and non-file transcripts",
+    async () => {
+      const unreadable = await writeTranscript({ cwd: path.join(workspace, "inaccessible") });
+      const dangling = await writeTranscript({});
+      await fs.rm(dangling.file);
+      await fs.symlink(path.join(workspace, "not-there"), dangling.file);
+      const nonFile = await writeTranscript({});
+      await fs.rm(nonFile.file);
+      await fs.mkdir(nonFile.file);
+      const { agent } = await indexAgent();
+      const projectDir = path.dirname(unreadable.file);
+      await fs.chmod(projectDir, 0);
+      try {
+        const result = await agent.batchGetSessions({
+          sessionIds: [unreadable.id, dangling.id, nonFile.id],
+        });
+        expect(result).toEqual({ sessions: [] });
+      } finally {
+        await fs.chmod(projectDir, 0o700);
+        await agent.dispose();
+      }
+    },
+  );
+
+  it("matches UUIDs exactly without case or whitespace normalization", async () => {
+    const sessionId = "aaaaaaaa-bbbb-4ccc-8ddd-eeeeeeeeeeee";
+    await writeTranscript({ sessionId });
+    const { agent } = await indexAgent();
+    const result = await agent.batchGetSessions({
+      sessionIds: [sessionId.toUpperCase(), ` ${sessionId} `, sessionId],
+    });
+    expect(result.sessions.map((row) => row.sessionId)).toEqual([sessionId]);
+    await agent.dispose();
+  });
+
+  it("omits empty, malformed, sidecar-only and unresolved-cwd records", async () => {
+    const empty = await writeTranscript({});
+    await fs.writeFile(empty.file, "");
+    const malformed = await writeTranscript({});
+    await fs.writeFile(malformed.file, "not json\n");
+    const sidecar = randomUUID();
+    const sidecarDir = path.join(configDir, "projects", encodeProjectPath(workspace), sidecar);
+    await fs.mkdir(sidecarDir, { recursive: true });
+    await fs.writeFile(path.join(sidecarDir, "custom-title.json"), '{"customTitle":"Saved"}');
+    const unresolved = await writeTranscript({
+      cwd: path.join(workspace, "unknown"),
+      recordCwd: null,
+    });
+    const { agent } = await indexAgent();
+    const ids = [empty.id, malformed.id, sidecar, unresolved.id];
+    const result = await agent.batchGetSessions({ sessionIds: ids });
+    expect(result).toEqual({ sessions: [] });
+    await agent.dispose();
+  });
+
+  it
+    .skipIf(process.platform === "win32" || process.getuid?.() === 0)
+    .each(["unreadable", "unreadable after a cached list", "a file", "a dangling symlink"])(
+    "rejects a projects root that is %s",
+    async (kind) => {
+      const found = await writeTranscript({});
+      const root = path.join(configDir, "projects");
+      const { agent } = await indexAgent();
+      try {
+        if (kind === "unreadable after a cached list") {
+          const old = new Date(Date.now() - 60_000);
+          await fs.utimes(root, old, old);
+          await agent.listSessions({});
+        }
+        if (kind.startsWith("unreadable")) {
+          await fs.chmod(root, 0);
+        } else {
+          await fs.rm(root, { recursive: true });
+          if (kind === "a file") await fs.writeFile(root, "not a store");
+          else await fs.symlink(path.join(workspace, "missing-store"), root);
+        }
+        for (const sessionId of [found.id, "retained-id"]) {
+          await expect(agent.batchGetSessions({ sessionIds: [sessionId] })).rejects.toThrow(
+            "Session store could not be read",
+          );
+        }
+      } finally {
+        if (kind.startsWith("unreadable")) await fs.chmod(root, 0o700);
+        await agent.dispose();
+      }
+    },
+  );
+
+  it("rejects under ACP v2 even when sessionIndex was declared", async () => {
+    const { agent } = createAgent({ v2: true });
+    await initializeClient(agent, air("sessionIndex"));
+    await expect(agent.batchGetSessions({ sessionIds: [] })).rejects.toMatchObject({
+      code: -32601,
+    });
+    await agent.dispose();
+  });
+});
+
 describe("session/list of a sessionIndex client", () => {
  const base = Date.parse("2026-03-01T00:00:00Z");

@@ -3528,7 +3957,8 @@ describe("paths that share a project directory", () => {
        .filter((s) => s.sessionId === mine.id);
    const removed = () =>
      changesFor(notifications, fromDotted.subscriptionId).flatMap((c) => c.removed);
-    expect(await waitFor(() => added().length > 0 && removed().length > 0)).toBe(true);
+    // Wait for mine.id itself: the other path's session can be removed first.
+    expect(await waitFor(() => added().length > 0 && removed().includes(mine.id))).toBe(true);
    expect(added().map((s) => [s.sessionId, s.cwd])).toEqual([[mine.id, dashed]]);
    // It may also name the other path's session, never listed here.
    expect(removed()).toContain(mine.id);
--- a/src/tests/ultracode-config.test.ts
+++ b/src/tests/ultracode-config.test.ts
@@ -0,0 +1,292 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+import type { ClientCapabilities } from "@agentclientprotocol/sdk/unstable";
+import type { ModelInfo, Query } from "@anthropic-ai/claude-agent-sdk";
+import type { AcpClient, ClaudeAcpAgent as ClaudeAcpAgentType } from "../acp-agent.js";
+import {
+  createUltracodeConfigOption,
+  modelSupportsUltracode,
+  readUltracodeSettings,
+  resolveUltracodeEnabled,
+  ULTRACODE_CONFIG_ID,
+  ULTRACODE_OFF,
+  ULTRACODE_ON,
+  ultracodeSupported,
+  ultracodeWorkflowsEnabled,
+} from "../session-ultracode.js";
+import { makeMockQuery } from "./helpers.js";
+
+const { querySpy } = vi.hoisted(() => ({ querySpy: vi.fn() }));
+
+vi.mock("@anthropic-ai/claude-agent-sdk", async () => {
+  const actual = await vi.importActual<any>("@anthropic-ai/claude-agent-sdk");
+  return { ...actual, query: querySpy };
+});
+
+const OPUS: ModelInfo = {
+  value: "opus",
+  displayName: "Opus",
+  description: "",
+  supportsEffort: true,
+  supportedEffortLevels: ["low", "medium", "high", "xhigh", "max"],
+};
+const FABLE: ModelInfo = {
+  value: "fable",
+  displayName: "Fable",
+  description: "",
+  supportsEffort: true,
+  supportedEffortLevels: ["low", "medium", "high", "xhigh", "max"],
+};
+// Opus 4.6 and Haiku 4.5 have no `xhigh` effort, so the CLI has no ultracode
+// for them either.
+const OLD_OPUS: ModelInfo = {
+  value: "claude-opus-4-6",
+  displayName: "Opus 4.6",
+  description: "",
+  supportsEffort: true,
+  supportedEffortLevels: ["low", "medium", "high", "max"],
+};
+
+function getSettingsQuery(getSettings: unknown): Query {
+  return { getSettings } as unknown as Query;
+}
+
+describe("ultracode helpers", () => {
+  it("builds a boolean option or an on/off select", () => {
+    expect(createUltracodeConfigOption(true, true)).toEqual({
+      id: ULTRACODE_CONFIG_ID,
+      name: "Ultracode",
+      description: "Dynamic workflows on every task, at any effort level",
+      category: "model_config",
+      type: "boolean",
+      currentValue: true,
+    });
+    expect(createUltracodeConfigOption(false, false)).toMatchObject({
+      type: "select",
+      currentValue: ULTRACODE_OFF,
+      options: [
+        { value: ULTRACODE_ON, name: "On" },
+        { value: ULTRACODE_OFF, name: "Off" },
+      ],
+    });
+  });
+
+  it("accepts booleans and the select strings", () => {
+    const request = (value: unknown) =>
+      ({ sessionId: "s", configId: ULTRACODE_CONFIG_ID, value }) as never;
+    expect(resolveUltracodeEnabled(request(true))).toBe(true);
+    expect(resolveUltracodeEnabled(request(ULTRACODE_OFF))).toBe(false);
+    expect(() => resolveUltracodeEnabled(request("maybe"))).toThrow(
+      "Invalid value for config option ultracode: maybe",
+    );
+  });
+
+  it("treats a model as supporting ultracode when it supports xhigh effort", () => {
+    expect(modelSupportsUltracode(OPUS)).toBe(true);
+    expect(modelSupportsUltracode(OLD_OPUS)).toBe(false);
+    expect(modelSupportsUltracode({ ...OPUS, supportsEffort: false })).toBe(false);
+    expect(modelSupportsUltracode(undefined)).toBe(false);
+  });
+
+  it("infers the workflows gate only when the start model can tell", () => {
+    expect(ultracodeWorkflowsEnabled({ available: true }, OLD_OPUS)).toBe(true);
+    expect(ultracodeWorkflowsEnabled({ available: false }, OPUS)).toBe(false);
+    // Opus 4.6 is unavailable regardless of workflows.
+    expect(ultracodeWorkflowsEnabled({ available: false }, OLD_OPUS)).toBeUndefined();
+    expect(ultracodeWorkflowsEnabled(undefined, OPUS)).toBeUndefined();
+
+    expect(ultracodeSupported(undefined, OPUS)).toBe(true);
+    expect(ultracodeSupported(false, OPUS)).toBe(false);
+    expect(ultracodeSupported(true, OLD_OPUS)).toBe(false);
+  });
+
+  it("reads the CLI's ultracode report and tolerates CLIs without one", async () => {
+    await expect(
+      readUltracodeSettings(
+        getSettingsQuery(async () => ({
+          applied: { ultracodeAvailable: true, ultracodeRequested: false },
+        })),
+      ),
+    ).resolves.toEqual({ available: true, requested: false });
+    await expect(
+      readUltracodeSettings(getSettingsQuery(async () => ({ applied: {} }))),
+    ).resolves.toEqual({ available: undefined, requested: undefined });
+    await expect(readUltracodeSettings(getSettingsQuery(undefined))).resolves.toBeUndefined();
+    await expect(
+      readUltracodeSettings(
+        getSettingsQuery(async () => {
+          throw new Error("unsupported control request");
+        }),
+      ),
+    ).resolves.toBeUndefined();
+  });
+});
+
+describe("ultracode session config option", () => {
+  let tempDir: string;
+  let originalClaudeConfigDir: string | undefined;
+
+  beforeEach(async () => {
+    tempDir = await fs.promises.mkdtemp(path.join(os.tmpdir(), "acp-ultracode-"));
+    originalClaudeConfigDir = process.env.CLAUDE_CONFIG_DIR;
+    process.env.CLAUDE_CONFIG_DIR = tempDir;
+    querySpy.mockReset();
+    vi.resetModules();
+  });
+
+  afterEach(async () => {
+    if (originalClaudeConfigDir) {
+      process.env.CLAUDE_CONFIG_DIR = originalClaudeConfigDir;
+    } else {
+      delete process.env.CLAUDE_CONFIG_DIR;
+    }
+    await fs.promises.rm(tempDir, { recursive: true, force: true });
+  });
+
+  async function createSession(opts: {
+    models?: ModelInfo[];
+    getSettings?: () => Promise<unknown>;
+    settings?: Record<string, unknown>;
+    clientCapabilities?: ClientCapabilities;
+  }) {
+    if (opts.settings) {
+      await fs.promises.writeFile(
+        path.join(tempDir, "settings.json"),
+        JSON.stringify(opts.settings),
+      );
+    }
+    const applyFlagSettings = vi.fn();
+    querySpy.mockReturnValue(
+      makeMockQuery({
+        initializationResult: async () => ({ models: opts.models ?? [OPUS, FABLE, OLD_OPUS] }),
+        applyFlagSettings,
+        ...(opts.getSettings ? { getSettings: opts.getSettings } : {}),
+      }),
+    );
+    const { ClaudeAcpAgent } = await import("../acp-agent.js");
+    const agent: ClaudeAcpAgentType = new ClaudeAcpAgent({
+      sessionUpdate: async () => {},
+      requestPermission: async () => ({ outcome: { outcome: "cancelled" } }),
+      readTextFile: async () => ({ content: "" }),
+      writeTextFile: async () => ({}),
+    } as unknown as AcpClient);
+    (agent as any).clientCapabilities = opts.clientCapabilities ?? {
+      session: { configOptions: { boolean: {} } },
+    };
+    const response = await (agent as any).createSession({
+      cwd: tempDir,
+      mcpServers: [],
+      _meta: { disableBuiltInTools: true },
+    });
+    const sessionId: string = response.sessionId;
+    const ultracodeOption = () =>
+      agent.sessions[sessionId].configOptions.find((o) => o.id === ULTRACODE_CONFIG_ID);
+    return { agent, sessionId, applyFlagSettings, ultracodeOption };
+  }
+
+  it("seeds the option from the CLI's report", async () => {
+    const { ultracodeOption, agent, sessionId } = await createSession({
+      getSettings: async () => ({
+        applied: { ultracodeAvailable: true, ultracodeRequested: true },
+      }),
+    });
+    expect(ultracodeOption()).toEqual(createUltracodeConfigOption(true, true));
+    expect(agent.sessions[sessionId].ultracodeEnabled).toBe(true);
+  });
+
+  it("hides the option while dynamic workflows are off, across model switches", async () => {
+    const { agent, sessionId, ultracodeOption } = await createSession({
+      getSettings: async () => ({
+        applied: { ultracodeAvailable: false, ultracodeRequested: false },
+      }),
+    });
+    expect(ultracodeOption()).toBeUndefined();
+
+    await agent.setSessionConfigOption({ sessionId, configId: "model", value: "fable" });
+    expect(ultracodeOption()).toBeUndefined();
+  });
+
+  it("follows the model's support and keeps the toggle across switches", async () => {
+    const { agent, sessionId, applyFlagSettings, ultracodeOption } = await createSession({
+      clientCapabilities: {},
+    });
+    expect(ultracodeOption()).toEqual(createUltracodeConfigOption(false, false));
+
+    await agent.setSessionConfigOption({
+      sessionId,
+      configId: ULTRACODE_CONFIG_ID,
+      value: ULTRACODE_ON,
+    });
+    expect(applyFlagSettings).toHaveBeenLastCalledWith({ ultracode: true });
+
+    await agent.setSessionConfigOption({ sessionId, configId: "model", value: "claude-opus-4-6" });
+    expect(ultracodeOption()).toBeUndefined();
+
+    await agent.setSessionConfigOption({ sessionId, configId: "model", value: "fable" });
+    expect(ultracodeOption()).toEqual(createUltracodeConfigOption(true, false));
+  });
+
+  it("keeps a toggled-on ultracode when effort changes, and not a toggled-off one", async () => {
+    // An effortLevel apply without an ultracode key turns ultracode off, so
+    // the effort picker must carry the session's toggle.
+    const { agent, sessionId, applyFlagSettings } = await createSession({
+      settings: { ultracode: true },
+    });
+
+    await agent.setSessionConfigOption({
+      sessionId,
+      configId: ULTRACODE_CONFIG_ID,
+      type: "boolean",
+      value: false,
+    });
+    expect(applyFlagSettings).toHaveBeenLastCalledWith({ ultracode: false });
+    await agent.setSessionConfigOption({ sessionId, configId: "effort", value: "high" });
+    expect(applyFlagSettings).toHaveBeenLastCalledWith({ effortLevel: "high" });
+
+    await agent.setSessionConfigOption({
+      sessionId,
+      configId: ULTRACODE_CONFIG_ID,
+      type: "boolean",
+      value: true,
+    });
+    await agent.setSessionConfigOption({ sessionId, configId: "effort", value: "low" });
+    expect(applyFlagSettings).toHaveBeenLastCalledWith({ effortLevel: "low", ultracode: true });
+  });
+
+  it("keeps ultracode on through the effort apply that follows a model switch", async () => {
+    // recommendedValue clients apply the new model's effort on every switch.
+    const { agent, sessionId, applyFlagSettings } = await createSession({
+      clientCapabilities: {
+        session: { configOptions: { boolean: {} } },
+        _meta: { jetbrains: { air: { version: 1, capabilities: ["recommendedValue"] } } },
+      },
+    });
+    await agent.setSessionConfigOption({
+      sessionId,
+      configId: ULTRACODE_CONFIG_ID,
+      type: "boolean",
+      value: true,
+    });
+
+    await agent.setSessionConfigOption({ sessionId, configId: "model", value: "fable" });
+    expect(applyFlagSettings).toHaveBeenLastCalledWith({ effortLevel: "medium", ultracode: true });
+  });
+
+  it("does not change session state when the SDK rejects the flag", async () => {
+    const { agent, sessionId, applyFlagSettings, ultracodeOption } = await createSession({});
+    applyFlagSettings.mockRejectedValueOnce(new Error("nope"));
+
+    await expect(
+      agent.setSessionConfigOption({
+        sessionId,
+        configId: ULTRACODE_CONFIG_ID,
+        type: "boolean",
+        value: true,
+      }),
+    ).rejects.toThrow("nope");
+    expect(agent.sessions[sessionId].ultracodeEnabled).toBe(false);
+    expect(ultracodeOption()).toEqual(createUltracodeConfigOption(false, true));
+  });
+});
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -14,8 +14,9 @@ export default defineConfig({
    // tests off the machine's real CLI and Claude config, and stops a run
    // from outliving its test (it wrote into temp config dirs being deleted).
    env: usesRealCli ? {} : { CLAUDE_CODE_EXECUTABLE: "/usr/bin/false" },
-    // Real-CLI runs may want a real gateway listing.
-    setupFiles: usesRealCli ? [] : ["src/tests/setup-no-network.ts"],
+    // Applies to real-CLI runs too: the gateway listing runs in the test process,
+    // and tests point `providers/set` at fake URLs like gateway.example.com.
+    setupFiles: ["src/tests/setup-no-network.ts"],
    include: [
      "src/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}",
      // Release tooling lives in scripts/ rather than src/ so it stays outside tsc's