chore(main): release 0.32.0 (#615 )

🤖 I have created a release *beep* *boop* --- ## [0.32.0](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.31.4...v0.32.0) (2026-05-03) ### Features * **deps-dev:** Bump nanoid from 3.3.11 to 3.3.12 ([#622](https://github.com/agentclientprotocol/claude-agent-acp/issues/622)) ([c78ac62](c78ac62d05)) * **deps:** Bump the minor group with 2 updates ([#619](https://github.com/agentclientprotocol/claude-agent-acp/issues/619)) ([6ccd37c](6ccd37ce94)) * **deps:** update to @anthropic-ai/claude-agent-sdk 0.2.126 ([#621](https://github.com/agentclientprotocol/claude-agent-acp/issues/621)) ([becc3b8](becc3b86e6)) * **deps:** Update to @anthropic-ai/claude-agent-sdk@0.2.123 ([#614](https://github.com/agentclientprotocol/claude-agent-acp/issues/614)) ([5b93119](5b9311938d)) ### Bug Fixes * emit a real diff when Write overwrites an existing file ([#618](https://github.com/agentclientprotocol/claude-agent-acp/issues/618)) ([8d7e220](8d7e22026e)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). Co-authored-by: acp-release-bot[bot] <246668977+acp-release-bot[bot]@users.noreply.github.com>
feat(deps): update to @anthropic-ai/claude-agent-sdk 0.2.126 (#621 )
2026-10-27 12:40:32 +00:00 · 2026-05-04 00:02:01 +02:00 · 2026-05-03 23:55:27 +02:00 · 2026-05-03 21:52:06 +00:00 · 2026-05-03 23:44:47 +02:00 · 2026-05-01 19:44:59 +02:00
15 changed files with 1289 additions and 327 deletions
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -11,6 +11,13 @@ updates:
      interval: "daily"
    allow:
      - dependency-type: "all"
+    ignore:
+      # Pinned to match the peer range of @anthropic-ai/claude-agent-sdk;
+      # newer minors break type compatibility between the two installed copies.
+      - dependency-name: "@anthropic-ai/sdk"
+        update-types:
+          - "version-update:semver-minor"
+          - "version-update:semver-major"
    groups:
      minor:
        update-types:
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "0.31.0"
+  ".": "0.32.0"
 }
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,48 @@
 # Changelog

+## [0.32.0](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.31.4...v0.32.0) (2026-05-03)
+
+
+### Features
+
+* **deps-dev:** Bump nanoid from 3.3.11 to 3.3.12 ([#622](https://github.com/agentclientprotocol/claude-agent-acp/issues/622)) ([c78ac62](https://github.com/agentclientprotocol/claude-agent-acp/commit/c78ac62d05283e5683b87b198923818f9f556a03))
+* **deps:** Bump the minor group with 2 updates ([#619](https://github.com/agentclientprotocol/claude-agent-acp/issues/619)) ([6ccd37c](https://github.com/agentclientprotocol/claude-agent-acp/commit/6ccd37ce947fbd55691f676344b15ef1266191ad))
+* **deps:** update to @anthropic-ai/claude-agent-sdk 0.2.126 ([#621](https://github.com/agentclientprotocol/claude-agent-acp/issues/621)) ([becc3b8](https://github.com/agentclientprotocol/claude-agent-acp/commit/becc3b86e60eb33e7823a0ef27d5aa99758750d7))
+* **deps:** Update to @anthropic-ai/claude-agent-sdk@0.2.123 ([#614](https://github.com/agentclientprotocol/claude-agent-acp/issues/614)) ([5b93119](https://github.com/agentclientprotocol/claude-agent-acp/commit/5b9311938d97f47400debd66f2b4792e50639c6b))
+
+
+### Bug Fixes
+
+* emit a real diff when Write overwrites an existing file ([#618](https://github.com/agentclientprotocol/claude-agent-acp/issues/618)) ([8d7e220](https://github.com/agentclientprotocol/claude-agent-acp/commit/8d7e22026e15d54208414bd9ad128eb86d41b451))
+
+## [0.31.4](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.31.3...v0.31.4) (2026-04-28)
+
+
+### Bug Fixes
+
+* gate auto mode on model support ([#604](https://github.com/agentclientprotocol/claude-agent-acp/issues/604)) ([ec47d34](https://github.com/agentclientprotocol/claude-agent-acp/commit/ec47d3446fa22e5895621f57c0a4497dbe044505))
+
+## [0.31.3](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.31.2...v0.31.3) (2026-04-28)
+
+
+### Bug Fixes
+
+* Rename effort config category to thought_level ([#609](https://github.com/agentclientprotocol/claude-agent-acp/issues/609)) ([76b4e96](https://github.com/agentclientprotocol/claude-agent-acp/commit/76b4e9650832e59a6b4915ad898fc66a065022fa))
+
+## [0.31.2](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.31.1...v0.31.2) (2026-04-28)
+
+
+### Bug Fixes
+
+* tolerate invalid values in settings.json ([#601](https://github.com/agentclientprotocol/claude-agent-acp/issues/601)) ([67af018](https://github.com/agentclientprotocol/claude-agent-acp/commit/67af018d0216238d8f3cd5bad04a55200518239b))
+
+## [0.31.1](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.31.0...v0.31.1) (2026-04-27)
+
+
+### Bug Fixes
+
+* detect glibc and use correct binary ([#599](https://github.com/agentclientprotocol/claude-agent-acp/issues/599)) ([f0801d5](https://github.com/agentclientprotocol/claude-agent-acp/commit/f0801d50b2390a3c48150b9b8507d30a70c18b84))
+
 ## [0.31.0](https://github.com/agentclientprotocol/claude-agent-acp/compare/v0.30.0...v0.31.0) (2026-04-24)


--- a/package-lock.json
+++ b/package-lock.json
@@ -1,16 +1,16 @@
 {
  "name": "@agentclientprotocol/claude-agent-acp",
-  "version": "0.31.0",
+  "version": "0.32.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "@agentclientprotocol/claude-agent-acp",
-      "version": "0.31.0",
+      "version": "0.32.0",
      "license": "Apache-2.0",
      "dependencies": {
-        "@agentclientprotocol/sdk": "0.20.0",
-        "@anthropic-ai/claude-agent-sdk": "0.2.119",
+        "@agentclientprotocol/sdk": "0.21.0",
+        "@anthropic-ai/claude-agent-sdk": "0.2.126",
        "zod": "^3.25.0 || ^4.0.0"
      },
      "bin": {
@@ -20,11 +20,11 @@
        "@anthropic-ai/sdk": "0.89.0",
        "@eslint/js": "10.0.1",
        "@types/node": "25.6.0",
-        "@typescript-eslint/eslint-plugin": "8.59.0",
-        "@typescript-eslint/parser": "8.59.0",
-        "eslint": "10.2.1",
+        "@typescript-eslint/eslint-plugin": "8.59.1",
+        "@typescript-eslint/parser": "8.59.1",
+        "eslint": "10.3.0",
        "eslint-config-prettier": "10.1.8",
-        "globals": "17.5.0",
+        "globals": "17.6.0",
        "prettier": "3.8.3",
        "ts-node": "10.9.2",
        "typescript": "6.0.3",
@@ -32,18 +32,18 @@
      }
    },
    "node_modules/@agentclientprotocol/sdk": {
-      "version": "0.20.0",
-      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-0.20.0.tgz",
-      "integrity": "sha512-BxEHyE4MvwyOsdyVPub1vEtyrq8E0JSdjC+ckXWimY1VabFCTXdPyXv2y2Omz1j+iod7Z8oBJDXFCJptM0GBqQ==",
+      "version": "0.21.0",
+      "resolved": "https://registry.npmjs.org/@agentclientprotocol/sdk/-/sdk-0.21.0.tgz",
+      "integrity": "sha512-ONj+Q8qOdNQp5XbH5jnMwzT9IKZJsSN0p0lkceS4GtUtNOPVLpNzSS8gqQdGMKfBvA0ESbkL8BTaSN1Rc9miEw==",
      "license": "Apache-2.0",
      "peerDependencies": {
        "zod": "^3.25.0 || ^4.0.0"
      }
    },
    "node_modules/@anthropic-ai/claude-agent-sdk": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk/-/claude-agent-sdk-0.2.119.tgz",
-      "integrity": "sha512-6AvthpsaOTlkn514brSGOcCSLHDXODnU+ExN1O3CJCjxr5RBcmzR057C9EIM0G7IchnXsRfMZgRO1QKsjTXdbA==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk/-/claude-agent-sdk-0.2.126.tgz",
+      "integrity": "sha512-4ZrVu0XUEwNG6wxvsLgppRAmSfAf3oeEMEUPhgazb0AXUUe/7W8MxwZKJWOffqSLWaNYzOt3ZCIL7NJY6toqWw==",
      "license": "SEE LICENSE IN README.md",
      "dependencies": {
        "@anthropic-ai/sdk": "^0.81.0",
@@ -53,23 +53,23 @@
        "node": ">=18.0.0"
      },
      "optionalDependencies": {
-        "@anthropic-ai/claude-agent-sdk-darwin-arm64": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-darwin-x64": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-linux-arm64": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-linux-arm64-musl": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-linux-x64": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-linux-x64-musl": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-win32-arm64": "0.2.119",
-        "@anthropic-ai/claude-agent-sdk-win32-x64": "0.2.119"
+        "@anthropic-ai/claude-agent-sdk-darwin-arm64": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-darwin-x64": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-linux-arm64": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-linux-arm64-musl": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-linux-x64": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-linux-x64-musl": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-win32-arm64": "0.2.126",
+        "@anthropic-ai/claude-agent-sdk-win32-x64": "0.2.126"
      },
      "peerDependencies": {
        "zod": "^4.0.0"
      }
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-darwin-arm64": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-arm64/-/claude-agent-sdk-darwin-arm64-0.2.119.tgz",
-      "integrity": "sha512-kxnG37SZqUata2Jcp/YQ0n9Y7o/sinE/8LdG4ltM1gePh+z+0Mfa4vBUUTEBMBFth9PTovKoesIuVuyFpvO/Cw==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-arm64/-/claude-agent-sdk-darwin-arm64-0.2.126.tgz",
+      "integrity": "sha512-JFlJBbeAlx7Ic5s4lGUN9SppobryXk/lIqPCvhp6KrJTQIerh3MIBzxsVIJ0MaDut7jVni/oYgsvDni7NIyqHA==",
      "cpu": [
        "arm64"
      ],
@@ -80,9 +80,9 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-darwin-x64": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-x64/-/claude-agent-sdk-darwin-x64-0.2.119.tgz",
-      "integrity": "sha512-9Aj8g3ELsmZuOFg17TCkikeg/Wt2ucVT8hOOPQUatzLd7BKhydrHLA0RP42nBpWECO1B/n/mPdQ4iS/LS3s2Fg==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-darwin-x64/-/claude-agent-sdk-darwin-x64-0.2.126.tgz",
+      "integrity": "sha512-J8BpMj16NK9FUaG3HnHSivyp4Xww9DKWHiC8QSHT9oiT8pH5IG7nl0jxyjIq/lY79evlTY+ubgDVWlMUhUAN/g==",
      "cpu": [
        "x64"
      ],
@@ -93,15 +93,12 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-linux-arm64": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-arm64/-/claude-agent-sdk-linux-arm64-0.2.119.tgz",
-      "integrity": "sha512-v3o464XkiYehp/OKidQQirxdVb+aGSvdJvHF2zH9p33W8M/NC21zwwh4dhwDnKsyrtBIgkt2CcMwzIl30r0OtA==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-arm64/-/claude-agent-sdk-linux-arm64-0.2.126.tgz",
+      "integrity": "sha512-LM+mnfQsgI+1i5mYZwIPDDf14NGBu5wbhzm5U8P11dCa2p8sXmKoWpkbO16BFM2NxeW44I/RXCxE5qFsbz4zcg==",
      "cpu": [
        "arm64"
      ],
-      "libc": [
-        "glibc"
-      ],
      "license": "SEE LICENSE IN LICENSE.md",
      "optional": true,
      "os": [
@@ -109,15 +106,12 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-linux-arm64-musl": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-arm64-musl/-/claude-agent-sdk-linux-arm64-musl-0.2.119.tgz",
-      "integrity": "sha512-IPGWgtz+gGnD7fxKAvSf913EUT/lYBTBE8EZ7lh3+x5ZP2859LWLmrCm053Lf3nMWo/CWikZsVPwkDVwpz6tIQ==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-arm64-musl/-/claude-agent-sdk-linux-arm64-musl-0.2.126.tgz",
+      "integrity": "sha512-GO0BnIUw3LQ3XAy+nipAabkN0GwQGPhHB6ITI4XLoR99fLHB3TA6WfyvTf0fnpxd25A+c/+UsAoxz4zBQaHlhA==",
      "cpu": [
        "arm64"
      ],
-      "libc": [
-        "musl"
-      ],
      "license": "SEE LICENSE IN LICENSE.md",
      "optional": true,
      "os": [
@@ -125,15 +119,12 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-linux-x64": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-x64/-/claude-agent-sdk-linux-x64-0.2.119.tgz",
-      "integrity": "sha512-9ePt4ZN+hsqDw4AgS4KtcWIGKfL9Oq28kwkrTER/QAcSrVKxiLonp81cCLzg7Ok/IUJu4Cfd71GZbFv/WE54zw==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-x64/-/claude-agent-sdk-linux-x64-0.2.126.tgz",
+      "integrity": "sha512-yaOTDcYCdscxC0LKg9w8IwSa5g+993WggFZJBTZpqvflA2+WMQeTarDnKlsFTCw9XUZkL8XZeBALYJGx0HutuA==",
      "cpu": [
        "x64"
      ],
-      "libc": [
-        "glibc"
-      ],
      "license": "SEE LICENSE IN LICENSE.md",
      "optional": true,
      "os": [
@@ -141,15 +132,12 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-linux-x64-musl": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-x64-musl/-/claude-agent-sdk-linux-x64-musl-0.2.119.tgz",
-      "integrity": "sha512-QYxFNAe4FFridPkKhGlNcNBJ0TaIygWYyvfI9g4kX0i+RVbresUWuZVkWY06ioJ0fXoixFJ+HNQBMB7dLrIp8Q==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-linux-x64-musl/-/claude-agent-sdk-linux-x64-musl-0.2.126.tgz",
+      "integrity": "sha512-ByJGO0+mu7EplxSFSCIHd7QWsXdrF3qgtzQ177o/j+oSppLoqR1ot5ktf8aw5oR3CC5lFHg4tqd6TnneQpEoIg==",
      "cpu": [
        "x64"
      ],
-      "libc": [
-        "musl"
-      ],
      "license": "SEE LICENSE IN LICENSE.md",
      "optional": true,
      "os": [
@@ -157,9 +145,9 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-win32-arm64": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-win32-arm64/-/claude-agent-sdk-win32-arm64-0.2.119.tgz",
-      "integrity": "sha512-p/TjcKQvkCYtXGPlR+mdyNwqCmvRcQL34Wtq0yUZ+iqmI/eyCe59IJ3AZrE0EZoqmiAevEYzatPIt9sncC9uxw==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-win32-arm64/-/claude-agent-sdk-win32-arm64-0.2.126.tgz",
+      "integrity": "sha512-gv3MOsOBkCx3LajOOIjD7AKsOtz/qNHsS2oshGt2GVoy7JA3XbCDeCetDjM6SorV4SE+7F/IH0UJdXe5ejI/Zg==",
      "cpu": [
        "arm64"
      ],
@@ -170,9 +158,9 @@
      ]
    },
    "node_modules/@anthropic-ai/claude-agent-sdk-win32-x64": {
-      "version": "0.2.119",
-      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-win32-x64/-/claude-agent-sdk-win32-x64-0.2.119.tgz",
-      "integrity": "sha512-k98Ju0wtktm6FhqTE/cXlVr6K4kGqBolVjEGzeKkW6ZILc7124euwNapAvkQCwMAavAxS/ZnO3jdKMtHtwTVTA==",
+      "version": "0.2.126",
+      "resolved": "https://registry.npmjs.org/@anthropic-ai/claude-agent-sdk-win32-x64/-/claude-agent-sdk-win32-x64-0.2.126.tgz",
+      "integrity": "sha512-oRV75HwyoOd1/t5+kipAM2g62CaElpKGvSBx3Ys4lCwCiFUyOnmet/O+hRXENsY6ShDeQZEcJL2UWljr2d5NQw==",
      "cpu": [
        "x64"
      ],
@@ -662,9 +650,6 @@
        "arm64"
      ],
      "dev": true,
-      "libc": [
-        "glibc"
-      ],
      "license": "MIT",
      "optional": true,
      "os": [
@@ -682,9 +667,6 @@
        "arm64"
      ],
      "dev": true,
-      "libc": [
-        "musl"
-      ],
      "license": "MIT",
      "optional": true,
      "os": [
@@ -702,9 +684,6 @@
        "ppc64"
      ],
      "dev": true,
-      "libc": [
-        "glibc"
-      ],
      "license": "MIT",
      "optional": true,
      "os": [
@@ -722,9 +701,6 @@
        "s390x"
      ],
      "dev": true,
-      "libc": [
-        "glibc"
-      ],
      "license": "MIT",
      "optional": true,
      "os": [
@@ -742,9 +718,6 @@
        "x64"
      ],
      "dev": true,
-      "libc": [
-        "glibc"
-      ],
      "license": "MIT",
      "optional": true,
      "os": [
@@ -762,9 +735,6 @@
        "x64"
      ],
      "dev": true,
-      "libc": [
-        "musl"
-      ],
      "license": "MIT",
      "optional": true,
      "os": [
@@ -947,17 +917,17 @@
      }
    },
    "node_modules/@typescript-eslint/eslint-plugin": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.59.0.tgz",
-      "integrity": "sha512-HyAZtpdkgZwpq8Sz3FSUvCR4c+ScbuWa9AksK2Jweub7w4M3yTz4O11AqVJzLYjy/B9ZWPyc81I+mOdJU/bDQw==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/eslint-plugin/-/eslint-plugin-8.59.1.tgz",
+      "integrity": "sha512-BOziFIfE+6osHO9FoJG4zjoHUcvI7fTNBSpdAwrNH0/TLvzjsk2oo8XSSOT2HhqUyhZPfHv4UOffoJ9oEEQ7Ag==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
        "@eslint-community/regexpp": "^4.12.2",
-        "@typescript-eslint/scope-manager": "8.59.0",
-        "@typescript-eslint/type-utils": "8.59.0",
-        "@typescript-eslint/utils": "8.59.0",
-        "@typescript-eslint/visitor-keys": "8.59.0",
+        "@typescript-eslint/scope-manager": "8.59.1",
+        "@typescript-eslint/type-utils": "8.59.1",
+        "@typescript-eslint/utils": "8.59.1",
+        "@typescript-eslint/visitor-keys": "8.59.1",
        "ignore": "^7.0.5",
        "natural-compare": "^1.4.0",
        "ts-api-utils": "^2.5.0"
@@ -970,22 +940,22 @@
        "url": "https://opencollective.com/typescript-eslint"
      },
      "peerDependencies": {
-        "@typescript-eslint/parser": "^8.59.0",
+        "@typescript-eslint/parser": "8.59.1",
        "eslint": "^8.57.0 || ^9.0.0 || ^10.0.0",
        "typescript": ">=4.8.4 <6.1.0"
      }
    },
    "node_modules/@typescript-eslint/parser": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-8.59.0.tgz",
-      "integrity": "sha512-TI1XGwKbDpo9tRW8UDIXCOeLk55qe9ZFGs8MTKU6/M08HWTw52DD/IYhfQtOEhEdPhLMT26Ka/x7p70nd3dzDg==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/parser/-/parser-8.59.1.tgz",
+      "integrity": "sha512-HDQH9O/47Dxi1ceDhBXdaldtf/WV9yRYMjbjCuNk3qnaTD564qwv61Y7+gTxwxRKzSrgO5uhtw584igXVuuZkA==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
-        "@typescript-eslint/scope-manager": "8.59.0",
-        "@typescript-eslint/types": "8.59.0",
-        "@typescript-eslint/typescript-estree": "8.59.0",
-        "@typescript-eslint/visitor-keys": "8.59.0",
+        "@typescript-eslint/scope-manager": "8.59.1",
+        "@typescript-eslint/types": "8.59.1",
+        "@typescript-eslint/typescript-estree": "8.59.1",
+        "@typescript-eslint/visitor-keys": "8.59.1",
        "debug": "^4.4.3"
      },
      "engines": {
@@ -1001,14 +971,14 @@
      }
    },
    "node_modules/@typescript-eslint/project-service": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/project-service/-/project-service-8.59.0.tgz",
-      "integrity": "sha512-Lw5ITrR5s5TbC19YSvlr63ZfLaJoU6vtKTHyB0GQOpX0W7d5/Ir6vUahWi/8Sps/nOukZQ0IB3SmlxZnjaKVnw==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/project-service/-/project-service-8.59.1.tgz",
+      "integrity": "sha512-+MuHQlHiEr00Of/IQbE/MmEoi44znZHbR/Pz7Opq4HryUOlRi+/44dro9Ycy8Fyo+/024IWtw8m4JUMCGTYxDg==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
-        "@typescript-eslint/tsconfig-utils": "^8.59.0",
-        "@typescript-eslint/types": "^8.59.0",
+        "@typescript-eslint/tsconfig-utils": "^8.59.1",
+        "@typescript-eslint/types": "^8.59.1",
        "debug": "^4.4.3"
      },
      "engines": {
@@ -1023,14 +993,14 @@
      }
    },
    "node_modules/@typescript-eslint/scope-manager": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/scope-manager/-/scope-manager-8.59.0.tgz",
-      "integrity": "sha512-UzR16Ut8IpA3Mc4DbgAShlPPkVm8xXMWafXxB0BocaVRHs8ZGakAxGRskF7FId3sdk9lgGD73GSFaWmWFDE4dg==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/scope-manager/-/scope-manager-8.59.1.tgz",
+      "integrity": "sha512-LwuHQI4pDOYVKvmH2dkaJo6YZCSgouVgnS/z7yBPKBMvgtBvyLqiLy9Z6b7+m/TRcX1NFYUqZetI5Y+aT4GEfg==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
-        "@typescript-eslint/types": "8.59.0",
-        "@typescript-eslint/visitor-keys": "8.59.0"
+        "@typescript-eslint/types": "8.59.1",
+        "@typescript-eslint/visitor-keys": "8.59.1"
      },
      "engines": {
        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
@@ -1041,9 +1011,9 @@
      }
    },
    "node_modules/@typescript-eslint/tsconfig-utils": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/tsconfig-utils/-/tsconfig-utils-8.59.0.tgz",
-      "integrity": "sha512-91Sbl3s4Kb3SybliIY6muFBmHVv+pYXfybC4Oolp3dvk8BvIE3wOPc+403CWIT7mJNkfQRGtdqghzs2+Z91Tqg==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/tsconfig-utils/-/tsconfig-utils-8.59.1.tgz",
+      "integrity": "sha512-/0nEyPbX7gRsk0Uwfe4ALwwgxuA66d/l2mhRDNlAvaj4U3juhUtJNq0DsY8M2AYwwb9rEq2hrC3IcIcEt++iJA==",
      "dev": true,
      "license": "MIT",
      "engines": {
@@ -1058,15 +1028,15 @@
      }
    },
    "node_modules/@typescript-eslint/type-utils": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/type-utils/-/type-utils-8.59.0.tgz",
-      "integrity": "sha512-3TRiZaQSltGqGeNrJzzr1+8YcEobKH9rHnqIp/1psfKFmhRQDNMGP5hBufanYTGznwShzVLs3Mz+gDN7HkWfXg==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/type-utils/-/type-utils-8.59.1.tgz",
+      "integrity": "sha512-klWPBR2ciQHS3f++ug/mVnWKPjBUo7icEL3FAO1lhAR1Z1i5NQYZ1EannMSRYcq5qCv5wNALlXr6fksRHyYl7w==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
-        "@typescript-eslint/types": "8.59.0",
-        "@typescript-eslint/typescript-estree": "8.59.0",
-        "@typescript-eslint/utils": "8.59.0",
+        "@typescript-eslint/types": "8.59.1",
+        "@typescript-eslint/typescript-estree": "8.59.1",
+        "@typescript-eslint/utils": "8.59.1",
        "debug": "^4.4.3",
        "ts-api-utils": "^2.5.0"
      },
@@ -1083,9 +1053,9 @@
      }
    },
    "node_modules/@typescript-eslint/types": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-8.59.0.tgz",
-      "integrity": "sha512-nLzdsT1gdOgFxxxwrlNVUBzSNBEEHJ86bblmk4QAS6stfig7rcJzWKqCyxFy3YRRHXDWEkb2NralA1nOYkkm/A==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/types/-/types-8.59.1.tgz",
+      "integrity": "sha512-ZDCjgccSdYPw5Bxh+my4Z0lJU96ZDN7jbBzvmEn0FZx3RtU1C7VWl6NbDx94bwY3V5YsgwRzJPOgeY2Q/nLG8A==",
      "dev": true,
      "license": "MIT",
      "engines": {
@@ -1097,16 +1067,16 @@
      }
    },
    "node_modules/@typescript-eslint/typescript-estree": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-8.59.0.tgz",
-      "integrity": "sha512-O9Re9P1BmBLFJyikRbQpLku/QA3/AueZNO9WePLBwQrvkixTmDe8u76B6CYUAITRl/rHawggEqUGn5QIkVRLMw==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-8.59.1.tgz",
+      "integrity": "sha512-OUd+vJS05sSkOip+BkZ/2NS8RMxrAAJemsC6vU3kmfLyeaJT0TftHkV9mcx2107MmsBVXXexhVu4F0TZXyMl4g==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
-        "@typescript-eslint/project-service": "8.59.0",
-        "@typescript-eslint/tsconfig-utils": "8.59.0",
-        "@typescript-eslint/types": "8.59.0",
-        "@typescript-eslint/visitor-keys": "8.59.0",
+        "@typescript-eslint/project-service": "8.59.1",
+        "@typescript-eslint/tsconfig-utils": "8.59.1",
+        "@typescript-eslint/types": "8.59.1",
+        "@typescript-eslint/visitor-keys": "8.59.1",
        "debug": "^4.4.3",
        "minimatch": "^10.2.2",
        "semver": "^7.7.3",
@@ -1125,16 +1095,16 @@
      }
    },
    "node_modules/@typescript-eslint/utils": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-8.59.0.tgz",
-      "integrity": "sha512-I1R/K7V07XsMJ12Oaxg/O9GfrysGTmCRhvZJBv0RE0NcULMzjqVpR5kRRQjHsz3J/bElU7HwCO7zkqL+MSUz+g==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/utils/-/utils-8.59.1.tgz",
+      "integrity": "sha512-3pIeoXhCeYH9FSCBI8P3iNwJlGuzPlYKkTlen2O9T1DSeeg8UG8jstq6BLk+Mda0qup7mgk4z4XL4OzRaxZ8LA==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
        "@eslint-community/eslint-utils": "^4.9.1",
-        "@typescript-eslint/scope-manager": "8.59.0",
-        "@typescript-eslint/types": "8.59.0",
-        "@typescript-eslint/typescript-estree": "8.59.0"
+        "@typescript-eslint/scope-manager": "8.59.1",
+        "@typescript-eslint/types": "8.59.1",
+        "@typescript-eslint/typescript-estree": "8.59.1"
      },
      "engines": {
        "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
@@ -1149,13 +1119,13 @@
      }
    },
    "node_modules/@typescript-eslint/visitor-keys": {
-      "version": "8.59.0",
-      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-8.59.0.tgz",
-      "integrity": "sha512-/uejZt4dSere1bx12WLlPfv8GktzcaDtuJ7s42/HEZ5zGj9oxRaD4bj7qwSunXkf+pbAhFt2zjpHYUiT5lHf0Q==",
+      "version": "8.59.1",
+      "resolved": "https://registry.npmjs.org/@typescript-eslint/visitor-keys/-/visitor-keys-8.59.1.tgz",
+      "integrity": "sha512-LdDNl6C5iJExcM0Yh0PwAIBb9PrSiCsWamF/JyEZawm3kFDnRoaq3LGE4bpyRao/fWeGKKyw7icx0YxrLFC5Cg==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
-        "@typescript-eslint/types": "8.59.0",
+        "@typescript-eslint/types": "8.59.1",
        "eslint-visitor-keys": "^5.0.0"
      },
      "engines": {
@@ -1672,9 +1642,9 @@
      }
    },
    "node_modules/es-module-lexer": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-2.0.0.tgz",
-      "integrity": "sha512-5POEcUuZybH7IdmGsD8wlf0AI55wMecM9rVBTI/qEAy2c1kTOm3DjFYjrBdI2K3BaJjJYfYFeRtM0t9ssnRuxw==",
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-2.1.0.tgz",
+      "integrity": "sha512-n27zTYMjYu1aj4MjCWzSP7G9r75utsaoc8m61weK+W8JMBGGQybd43GstCXZ3WNmSFtGT9wi59qQTW6mhTR5LQ==",
      "dev": true,
      "license": "MIT"
    },
@@ -1710,9 +1680,9 @@
      }
    },
    "node_modules/eslint": {
-      "version": "10.2.1",
-      "resolved": "https://registry.npmjs.org/eslint/-/eslint-10.2.1.tgz",
-      "integrity": "sha512-wiyGaKsDgqXvF40P8mDwiUp/KQjE1FdrIEJsM8PZ3XCiniTMXS3OHWWUe5FI5agoCnr8x4xPrTDZuxsBlNHl+Q==",
+      "version": "10.3.0",
+      "resolved": "https://registry.npmjs.org/eslint/-/eslint-10.3.0.tgz",
+      "integrity": "sha512-XbEXaRva5cF0ZQB8w6MluHA0kZZfV2DuCMJ3ozyEOHLwDpZX2Lmm/7Pp0xdJmI0GL1W05VH5VwIFHEm1Vcw2gw==",
      "dev": true,
      "license": "MIT",
      "dependencies": {
@@ -2031,9 +2001,9 @@
      }
    },
    "node_modules/express-rate-limit": {
-      "version": "8.4.0",
-      "resolved": "https://registry.npmjs.org/express-rate-limit/-/express-rate-limit-8.4.0.tgz",
-      "integrity": "sha512-gDK8yiqKxrGta+3WtON59arrrw6GLmadA1qoFgYXzdcch8fmKDID2XqO8itsi3f1wufXYPT51387dN6cvVBS3Q==",
+      "version": "8.4.1",
+      "resolved": "https://registry.npmjs.org/express-rate-limit/-/express-rate-limit-8.4.1.tgz",
+      "integrity": "sha512-NGVYwQSAyEQgzxX1iCM978PP9AdO/hW93gMcF6ZwQCm+rFvLsBH6w4xcXWTcliS8La5EPRN3p9wzItqBwJrfNw==",
      "license": "MIT",
      "dependencies": {
        "ip-address": "10.1.0"
@@ -2267,9 +2237,9 @@
      }
    },
    "node_modules/globals": {
-      "version": "17.5.0",
-      "resolved": "https://registry.npmjs.org/globals/-/globals-17.5.0.tgz",
-      "integrity": "sha512-qoV+HK2yFl/366t2/Cb3+xxPUo5BuMynomoDmiaZBIdbs+0pYbjfZU+twLhGKp4uCZ/+NbtpVepH5bGCxRyy2g==",
+      "version": "17.6.0",
+      "resolved": "https://registry.npmjs.org/globals/-/globals-17.6.0.tgz",
+      "integrity": "sha512-sepffkT8stwnIYbsMBpoCHJuJM5l98FUF2AnE07hfvE0m/qp3R586hw4jF4uadbhvg1ooIdzuu7CsfD2jzCaNA==",
      "dev": true,
      "license": "MIT",
      "engines": {
@@ -2316,9 +2286,9 @@
      }
    },
    "node_modules/hono": {
-      "version": "4.12.15",
-      "resolved": "https://registry.npmjs.org/hono/-/hono-4.12.15.tgz",
-      "integrity": "sha512-qM0jDhFEaCBb4TxoW7f53Qrpv9RBiayUHo0S52JudprkhvpjIrGoU1mnnr29Fvd1U335ZFPZQY1wlkqgfGXyLg==",
+      "version": "4.12.16",
+      "resolved": "https://registry.npmjs.org/hono/-/hono-4.12.16.tgz",
+      "integrity": "sha512-jN0ZewiNAWSe5khM3EyCmBb250+b40wWbwNILNfEvq84VREWwOIkuUsFONk/3i3nqkz7Oe1PcpM2mwQEK2L9Kg==",
      "license": "MIT",
      "engines": {
        "node": ">=16.9.0"
@@ -2440,9 +2410,9 @@
      "license": "ISC"
    },
    "node_modules/jose": {
-      "version": "6.2.2",
-      "resolved": "https://registry.npmjs.org/jose/-/jose-6.2.2.tgz",
-      "integrity": "sha512-d7kPDd34KO/YnzaDOlikGpOurfF0ByC2sEV4cANCtdqLlTfBlw2p14O/5d/zv40gJPbIQxfES3nSx1/oYNyuZQ==",
+      "version": "6.2.3",
+      "resolved": "https://registry.npmjs.org/jose/-/jose-6.2.3.tgz",
+      "integrity": "sha512-YYVDInQKFJfR/xa3ojUTl8c2KoTwiL1R5Wg9YCydwH0x0B9grbzlg5HC7mMjCtUJjbQ/YnGEZIhI5tCgfTb4Hw==",
      "license": "MIT",
      "funding": {
        "url": "https://github.com/sponsors/panva"
@@ -2654,9 +2624,6 @@
        "arm64"
      ],
      "dev": true,
-      "libc": [
-        "glibc"
-      ],
      "license": "MPL-2.0",
      "optional": true,
      "os": [
@@ -2678,9 +2645,6 @@
        "arm64"
      ],
      "dev": true,
-      "libc": [
-        "musl"
-      ],
      "license": "MPL-2.0",
      "optional": true,
      "os": [
@@ -2702,9 +2666,6 @@
        "x64"
      ],
      "dev": true,
-      "libc": [
-        "glibc"
-      ],
      "license": "MPL-2.0",
      "optional": true,
      "os": [
@@ -2726,9 +2687,6 @@
        "x64"
      ],
      "dev": true,
-      "libc": [
-        "musl"
-      ],
      "license": "MPL-2.0",
      "optional": true,
      "os": [
@@ -2895,9 +2853,9 @@
      "license": "MIT"
    },
    "node_modules/nanoid": {
-      "version": "3.3.11",
-      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.11.tgz",
-      "integrity": "sha512-N8SpfPUnUp1bK+PMYW8qSWdl9U+wwNWI4QKxOYDy9JAro3WMX7p2OeVRF9v+347pnakNevPmiHhNmZ2HbFA76w==",
+      "version": "3.3.12",
+      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.12.tgz",
+      "integrity": "sha512-ZB9RH/39qpq5Vu6Y+NmUaFhQR6pp+M2Xt76XBnEwDaGcVAqhlvxrl3B2bKS5D3NH3QR76v3aSrKaF/Kiy7lEtQ==",
      "dev": true,
      "funding": [
        {
@@ -3107,9 +3065,9 @@
      }
    },
    "node_modules/postcss": {
-      "version": "8.5.10",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.10.tgz",
-      "integrity": "sha512-pMMHxBOZKFU6HgAZ4eyGnwXF/EvPGGqUr0MnZ5+99485wwW41kW91A4LOGxSHhgugZmSChL5AlElNdwlNgcnLQ==",
+      "version": "8.5.13",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.13.tgz",
+      "integrity": "sha512-qif0+jGGZoLWdHey3UFHHWP0H7Gbmsk8T5VEqyYFbWqPr1XqvLGBbk/sl8V5exGmcYJklJOhOQq1pV9IcsiFag==",
      "dev": true,
      "funding": [
        {
@@ -3493,9 +3451,9 @@
      "license": "MIT"
    },
    "node_modules/tinyexec": {
-      "version": "1.1.1",
-      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-1.1.1.tgz",
-      "integrity": "sha512-VKS/ZaQhhkKFMANmAOhhXVoIfBXblQxGX1myCQ2faQrfmobMftXeJPcZGp0gS07ocvGJWDLZGyOZDadDBqYIJg==",
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-1.1.2.tgz",
+      "integrity": "sha512-dAqSqE/RabpBKI8+h26GfLq6Vb3JVXs30XYQjdMjaj/c2tS8IYYMbIzP599KtRj7c57/wYApb3QjgRgXmrCukA==",
      "dev": true,
      "license": "MIT",
      "engines": {
@@ -3932,9 +3890,9 @@
      }
    },
    "node_modules/zod": {
-      "version": "4.3.6",
-      "resolved": "https://registry.npmjs.org/zod/-/zod-4.3.6.tgz",
-      "integrity": "sha512-rftlrkhHZOcjDwkGlnUtZZkvaPHCsDATp4pGpuOOMDaTdDDXF91wuVDJoWoPsKX/3YPQ5fHuF3STjcYyKr+Qhg==",
+      "version": "4.4.1",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-4.4.1.tgz",
+      "integrity": "sha512-a6ENMBBGZBsnlSebQ/eKCguSBeGKSf4O7BPnqVPmYGtpBYI7VSqoVqw+QcB7kPRjbqPwhYTpFbVj/RqNz/CT0Q==",
      "license": "MIT",
      "funding": {
        "url": "https://github.com/sponsors/colinhacks"
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
  "publishConfig": {
    "access": "public"
  },
-  "version": "0.31.0",
+  "version": "0.32.0",
  "description": "An ACP-compatible coding agent powered by the Claude Agent SDK (TypeScript)",
  "main": "dist/lib.js",
  "types": "dist/lib.d.ts",
@@ -60,19 +60,19 @@
  "author": "Zed Industries",
  "license": "Apache-2.0",
  "dependencies": {
-    "@agentclientprotocol/sdk": "0.20.0",
-    "@anthropic-ai/claude-agent-sdk": "0.2.119",
+    "@agentclientprotocol/sdk": "0.21.0",
+    "@anthropic-ai/claude-agent-sdk": "0.2.126",
    "zod": "^3.25.0 || ^4.0.0"
  },
  "devDependencies": {
    "@anthropic-ai/sdk": "0.89.0",
    "@eslint/js": "10.0.1",
    "@types/node": "25.6.0",
-    "@typescript-eslint/eslint-plugin": "8.59.0",
-    "@typescript-eslint/parser": "8.59.0",
-    "eslint": "10.2.1",
+    "@typescript-eslint/eslint-plugin": "8.59.1",
+    "@typescript-eslint/parser": "8.59.1",
+    "eslint": "10.3.0",
    "eslint-config-prettier": "10.1.8",
-    "globals": "17.5.0",
+    "globals": "17.6.0",
    "prettier": "3.8.3",
    "ts-node": "10.9.2",
    "typescript": "6.0.3",
--- a/src/acp-agent.ts
+++ b/src/acp-agent.ts
@@ -73,7 +73,7 @@ import {
  planEntries,
  registerHookCallback,
  toolInfoFromToolUse,
-  toolUpdateFromEditToolResponse,
+  toolUpdateFromDiffToolResponse,
  toolUpdateFromToolResult,
 } from "./tools.js";
 import { nodeToWebReadable, nodeToWebWritable, Pushable, unreachable } from "./utils.js";
@@ -274,12 +274,22 @@ export async function claudeCliPath(): Promise<string> {
  const { createRequire } = await import("node:module");
  const req = createRequire(import.meta.resolve("@anthropic-ai/claude-agent-sdk"));
  const ext = process.platform === "win32" ? ".exe" : "";
+  // On linux, both glibc and musl variants may be installed side-by-side
+  // (e.g. bunx hydrates every optional dep), so picking one by trial is
+  // unreliable: the wrong binary segfaults at runtime instead of failing to
+  // spawn. Detect the runtime libc and prefer the matching variant, falling
+  // back to the other only if the preferred one isn't installed.
  const candidates =
    process.platform === "linux"
-      ? [
-          `@anthropic-ai/claude-agent-sdk-linux-${process.arch}-musl/claude${ext}`,
-          `@anthropic-ai/claude-agent-sdk-linux-${process.arch}/claude${ext}`,
-        ]
+      ? isMuslLibc()
+        ? [
+            `@anthropic-ai/claude-agent-sdk-linux-${process.arch}-musl/claude${ext}`,
+            `@anthropic-ai/claude-agent-sdk-linux-${process.arch}/claude${ext}`,
+          ]
+        : [
+            `@anthropic-ai/claude-agent-sdk-linux-${process.arch}/claude${ext}`,
+            `@anthropic-ai/claude-agent-sdk-linux-${process.arch}-musl/claude${ext}`,
+          ]
      : [`@anthropic-ai/claude-agent-sdk-${process.platform}-${process.arch}/claude${ext}`];
  for (const candidate of candidates) {
    try {
@@ -294,6 +304,15 @@ export async function claudeCliPath(): Promise<string> {
  );
 }

+function isMuslLibc(): boolean {
+  // process.report.getReport().header.glibcVersionRuntime is populated when
+  // Node is dynamically linked against glibc, and absent on musl.
+  const report = process.report?.getReport() as
+    | { header?: { glibcVersionRuntime?: string } }
+    | undefined;
+  return !report?.header?.glibcVersionRuntime;
+}
+
 function shouldHideClaudeAuth(): boolean {
  return process.argv.includes("--hide-claude-auth");
 }
@@ -366,29 +385,36 @@ const PERMISSION_MODE_ALIASES: Record<string, PermissionMode> = {
  bypass: "bypassPermissions",
 };

-export function resolvePermissionMode(defaultMode?: unknown): PermissionMode {
+export function resolvePermissionMode(
+  defaultMode?: unknown,
+  logger: Logger = console,
+): PermissionMode {
  if (defaultMode === undefined) {
    return "default";
  }

  if (typeof defaultMode !== "string") {
-    throw new Error("Invalid permissions.defaultMode: expected a string.");
+    logger.error("Ignoring permissions.defaultMode from settings: expected a string.");
+    return "default";
  }

  const normalized = defaultMode.trim().toLowerCase();
  if (normalized === "") {
-    throw new Error("Invalid permissions.defaultMode: expected a non-empty string.");
+    logger.error("Ignoring permissions.defaultMode from settings: expected a non-empty string.");
+    return "default";
  }

  const mapped = PERMISSION_MODE_ALIASES[normalized];
  if (!mapped) {
-    throw new Error(`Invalid permissions.defaultMode: ${defaultMode}.`);
+    logger.error(`Ignoring permissions.defaultMode from settings: unknown value '${defaultMode}'.`);
+    return "default";
  }

  if (mapped === "bypassPermissions" && !ALLOW_BYPASS) {
-    throw new Error(
-      "Invalid permissions.defaultMode: bypassPermissions is not available when running as root.",
+    logger.error(
+      "Ignoring permissions.defaultMode from settings: bypassPermissions is not available when running as root.",
    );
+    return "default";
  }

  return mapped;
@@ -1283,7 +1309,7 @@ export class ClaudeAcpAgent implements Agent {
    // effort changes and effort changes induced by a model switch go through
    // the same path.

-    await this.applyConfigOptionValue(session, params.configId, resolvedValue);
+    await this.applyConfigOptionValue(params.sessionId, session, params.configId, resolvedValue);

    return { configOptions: session.configOptions };
  }
@@ -1300,8 +1326,17 @@ export class ClaudeAcpAgent implements Agent {
      default:
        throw new Error("Invalid Mode");
    }
+
+    const session = this.sessions[sessionId];
+    if (!session) {
+      throw new Error("Session not found");
+    }
+    if (!session.modes.availableModes.some((mode) => mode.id === modeId)) {
+      throw new Error(`Mode ${modeId} is not available in this session`);
+    }
+
    try {
-      await this.sessions[sessionId].query.setPermissionMode(modeId);
+      await session.query.setPermissionMode(modeId);
    } catch (error) {
      if (error instanceof Error) {
        if (!error.message) {
@@ -1371,7 +1406,7 @@ export class ClaudeAcpAgent implements Agent {
      }

      if (toolName === "ExitPlanMode") {
-        const options = [
+        const optionsAll = [
          { kind: "allow_always", name: 'Yes, and use "auto" mode', optionId: "auto" },
          {
            kind: "allow_always",
@@ -1382,12 +1417,20 @@ export class ClaudeAcpAgent implements Agent {
          { kind: "reject_once", name: "No, keep planning", optionId: "plan" },
        ];
        if (ALLOW_BYPASS) {
-          options.unshift({
+          optionsAll.unshift({
            kind: "allow_always",
            name: "Yes, and bypass permissions",
            optionId: "bypassPermissions",
          });
        }
+        // Filter against the session's currently-advertised modes so we never
+        // present options the active model can't honor (e.g. `auto` on Haiku).
+        // `bypassPermissions` is already covered by `availableModes` via
+        // `buildAvailableModes`/`ALLOW_BYPASS`. The `plan` option is a
+        // "keep planning" reject path; it's always present in `availableModes`.
+        const options = optionsAll.filter((o) =>
+          session.modes.availableModes.some((m) => m.id === o.optionId),
+        );

        const response = await this.client.requestPermission({
          options,
@@ -1406,27 +1449,30 @@ export class ClaudeAcpAgent implements Agent {
        if (signal.aborted || response.outcome?.outcome === "cancelled") {
          throw new Error("Tool use aborted");
        }
+        const selectedMode =
+          response.outcome?.outcome === "selected" ? response.outcome.optionId : undefined;
+        const selectedModeWasOffered = options.some((option) => option.optionId === selectedMode);
        if (
-          response.outcome?.outcome === "selected" &&
-          (response.outcome.optionId === "default" ||
-            response.outcome.optionId === "acceptEdits" ||
-            response.outcome.optionId === "auto" ||
-            response.outcome.optionId === "bypassPermissions")
+          selectedModeWasOffered &&
+          (selectedMode === "default" ||
+            selectedMode === "acceptEdits" ||
+            selectedMode === "auto" ||
+            selectedMode === "bypassPermissions")
        ) {
          await this.client.sessionUpdate({
            sessionId,
            update: {
              sessionUpdate: "current_mode_update",
-              currentModeId: response.outcome.optionId,
+              currentModeId: selectedMode,
            },
          });
-          await this.updateConfigOption(sessionId, "mode", response.outcome.optionId);
+          await this.updateConfigOption(sessionId, "mode", selectedMode);

          return {
            behavior: "allow",
            updatedInput: toolInput,
            updatedPermissions: suggestions ?? [
-              { type: "setMode", mode: response.outcome.optionId, destination: "session" },
+              { type: "setMode", mode: selectedMode, destination: "session" },
            ],
          };
        } else {
@@ -1524,7 +1570,7 @@ export class ClaudeAcpAgent implements Agent {
    const session = this.sessions[sessionId];
    if (!session) return;

-    await this.applyConfigOptionValue(session, configId, value);
+    await this.applyConfigOptionValue(sessionId, session, configId, value);

    await this.client.sessionUpdate({
      sessionId,
@@ -1536,13 +1582,16 @@ export class ClaudeAcpAgent implements Agent {
  }

  private async applyConfigOptionValue(
+    sessionId: string,
    session: Session,
    configId: string,
    value: string,
  ): Promise<void> {
-    // Sync top-level session state
    if (configId === "mode") {
      session.modes = { ...session.modes, currentModeId: value };
+      session.configOptions = session.configOptions.map((o) =>
+        o.id === configId && typeof o.currentValue === "string" ? { ...o, currentValue: value } : o,
+      );
    } else if (configId === "model") {
      if (session.models.currentModelId !== value) {
        // The cached context window was learned for the previous model; reset
@@ -1552,10 +1601,38 @@ export class ClaudeAcpAgent implements Agent {
        session.contextWindowSize = inferContextWindowFromModel(value) ?? DEFAULT_CONTEXT_WINDOW;
      }
      session.models = { ...session.models, currentModelId: value };
-    }

-    // Update configOptions
-    if (configId === "model") {
+      // Recompute availableModes for the new model and clamp the current
+      // mode if the SDK no longer offers it (today: "auto" on Haiku).
+      // `ModelInfo.supportsAutoMode` is the canonical SDK signal.
+      const newModelInfo = session.modelInfos.find((m) => m.value === value);
+      const newAvailableModes = buildAvailableModes(newModelInfo);
+      // Capture BEFORE mutating session.modes so the log message reflects
+      // the invalidated mode rather than "default".
+      const previousModeId = session.modes.currentModeId;
+      let modeDowngraded = false;
+      if (!newAvailableModes.some((m) => m.id === previousModeId)) {
+        session.modes = {
+          availableModes: newAvailableModes,
+          currentModeId: "default",
+        };
+        try {
+          await session.query.setPermissionMode("default");
+        } catch (err) {
+          // Failing the entire model switch over a bookkeeping sync error is
+          // worse UX than logging and continuing; the user explicitly asked
+          // to change models. The next setPermissionMode from the user will
+          // either succeed or surface a fresh error.
+          this.logger.error(
+            `Failed to sync permissionMode to "default" after model switch invalidated "${previousModeId}":`,
+            err,
+          );
+        }
+        modeDowngraded = true;
+      } else {
+        session.modes = { ...session.modes, availableModes: newAvailableModes };
+      }
+
      // Rebuild config options since effort levels depend on the selected model
      const effortOpt = session.configOptions.find((o) => o.id === "effort");
      const currentEffort =
@@ -1576,6 +1653,22 @@ export class ClaudeAcpAgent implements Agent {
          effortLevel: newEffort as Settings["effortLevel"],
        });
      }
+
+      // Emit current_mode_update only after session.modes AND
+      // session.configOptions have been fully reconciled. This way, a failure
+      // in the configOptions/effort rebuild above can't leave the client with
+      // a clamped currentModeId but stale configOptions, and the notification
+      // still precedes the caller's config_option_update so order-sensitive
+      // clients update currentModeId before re-rendering the option list.
+      if (modeDowngraded) {
+        await this.client.sessionUpdate({
+          sessionId,
+          update: {
+            sessionUpdate: "current_mode_update",
+            currentModeId: "default",
+          },
+        });
+      }
    } else {
      session.configOptions = session.configOptions.map((o) =>
        o.id === configId && typeof o.currentValue === "string" ? { ...o, currentValue: value } : o,
@@ -1701,6 +1794,7 @@ export class ClaudeAcpAgent implements Agent {

    const permissionMode = resolvePermissionMode(
      settingsManager.getSettings().permissions?.defaultMode,
+      this.logger,
    );

    // Extract options from _meta if provided
@@ -1760,7 +1854,7 @@ export class ClaudeAcpAgent implements Agent {
      allowDangerouslySkipPermissions: ALLOW_BYPASS,
      permissionMode,
      canUseTool: this.canUseTool(sessionId),
-      pathToClaudeCodeExecutable: process.env.CLAUDE_CODE_EXECUTABLE,
+      pathToClaudeCodeExecutable: process.env.CLAUDE_CODE_EXECUTABLE ?? (await claudeCliPath()),
      extraArgs: {
        ...userProvidedOptions?.extraArgs,
        "replay-user-messages": "",
@@ -1839,46 +1933,52 @@ export class ClaudeAcpAgent implements Agent {
      );
    }

-    const models = await getAvailableModels(q, initializationResult.models, settingsManager);
+    const models = await getAvailableModels(
+      q,
+      initializationResult.models,
+      settingsManager,
+      this.logger,
+    );

-    const availableModes = [
-      {
-        id: "auto",
-        name: "Auto",
-        description: "Use a model classifier to approve/deny permission prompts",
-      },
-      {
-        id: "default",
-        name: "Default",
-        description: "Standard behavior, prompts for dangerous operations",
-      },
-      {
-        id: "acceptEdits",
-        name: "Accept Edits",
-        description: "Auto-accept file edit operations",
-      },
-      {
-        id: "plan",
-        name: "Plan Mode",
-        description: "Planning mode, no actual tool execution",
-      },
-      {
-        id: "dontAsk",
-        name: "Don't Ask",
-        description: "Don't prompt for permissions, deny if not pre-approved",
-      },
-    ];
-    // Only works in non-root mode
-    if (ALLOW_BYPASS) {
-      availableModes.push({
-        id: "bypassPermissions",
-        name: "Bypass Permissions",
-        description: "Bypass all permission checks",
-      });
+    // Gate `auto` (and future model-specific modes) on the resolved model's
+    // `ModelInfo`. See `buildAvailableModes` for the canonical SDK signal.
+    const currentModelInfo = initializationResult.models.find(
+      (m) => m.value === models.currentModelId,
+    );
+    const availableModes = buildAvailableModes(currentModelInfo);
+
+    // Clamp `permissionMode` if the resolved session does not offer it. The
+    // common case is `permissions.defaultMode: "auto"` resolving to a model
+    // that does not support auto mode (e.g. Haiku); without this clamp the
+    // SDK would later throw `"auto mode unavailable for this model"` from
+    // `setPermissionMode`. Keep `permissionMode` as the resolved user intent
+    // (matches what was passed into `options.permissionMode` above) and use
+    // `effectiveMode` for the post-clamp value the session actually runs in.
+    let effectiveMode: PermissionMode = permissionMode;
+    if (!availableModes.some((m) => m.id === effectiveMode)) {
+      if (effectiveMode === "auto") {
+        this.logger.error(
+          `permissions.defaultMode "auto" is not available for model ` +
+            `"${models.currentModelId}"; falling back to "default".`,
+        );
+      } else {
+        this.logger.error(
+          `permissions.defaultMode "${effectiveMode}" is not available in ` +
+            `this session; falling back to "default".`,
+        );
+      }
+      effectiveMode = "default";
+      // Sync the SDK so it doesn't keep "auto" cached internally. Wrapped in
+      // try/catch since failing here would abort session creation entirely.
+      try {
+        await q.setPermissionMode("default");
+      } catch (err) {
+        this.logger.error("Failed to sync clamped permissionMode to SDK:", err);
+      }
    }

    const modes = {
-      currentModeId: permissionMode,
+      currentModeId: effectiveMode,
      availableModes,
    };

@@ -2021,6 +2121,58 @@ function createEnvForGateway(gatewayMeta?: GatewayAuthMeta) {
  };
 }

+/**
+ * Build the list of permission modes the agent will advertise for the given
+ * model. `auto` is gated by `ModelInfo.supportsAutoMode === true`, which is
+ * the SDK's model-level availability signal. `undefined`/`false` both exclude
+ * `auto`. `bypassPermissions` is still gated by `ALLOW_BYPASS`.
+ */
+function buildAvailableModes(modelInfo: ModelInfo | undefined): SessionModeState["availableModes"] {
+  const modes: SessionModeState["availableModes"] = [];
+
+  // Only advertise "auto" when the SDK reports the model supports it.
+  if (modelInfo?.supportsAutoMode === true) {
+    modes.push({
+      id: "auto",
+      name: "Auto",
+      description: "Use a model classifier to approve/deny permission prompts",
+    });
+  }
+
+  modes.push(
+    {
+      id: "default",
+      name: "Default",
+      description: "Standard behavior, prompts for dangerous operations",
+    },
+    {
+      id: "acceptEdits",
+      name: "Accept Edits",
+      description: "Auto-accept file edit operations",
+    },
+    {
+      id: "plan",
+      name: "Plan Mode",
+      description: "Planning mode, no actual tool execution",
+    },
+    {
+      id: "dontAsk",
+      name: "Don't Ask",
+      description: "Don't prompt for permissions, deny if not pre-approved",
+    },
+  );
+
+  if (ALLOW_BYPASS) {
+    modes.push({
+      id: "bypassPermissions",
+      name: "Bypass Permissions",
+      description: "Bypass all permission checks",
+    });
+  }
+
+  return modes;
+}
+
 function buildConfigOptions(
  modes: SessionModeState,
  models: SessionModelState,
@@ -2087,7 +2239,7 @@ function buildConfigOptions(
      id: "effort",
      name: "Effort",
      description: "Available effort levels for this model",
-      category: "effort",
+      category: "thought_level",
      type: "select",
      currentValue: validEffort,
      options: effortOptions,
@@ -2170,10 +2322,27 @@ function resolveModelPreference(models: ModelInfo[], preference: string): ModelI
  return bestMatch;
 }

+function resolveSettingsModel(
+  models: ModelInfo[],
+  settingsModel: unknown,
+  logger: Logger,
+): ModelInfo | null {
+  if (settingsModel === undefined) {
+    return null;
+  }
+  if (typeof settingsModel !== "string") {
+    const typeLabel = settingsModel === null ? "null" : typeof settingsModel;
+    logger.error(`Ignoring model from settings: expected a string, got ${typeLabel}.`);
+    return null;
+  }
+  return resolveModelPreference(models, settingsModel);
+}
+
 async function getAvailableModels(
  query: Query,
  models: ModelInfo[],
  settingsManager: SettingsManager,
+  logger: Logger,
 ): Promise<SessionModelState> {
  const settings = settingsManager.getSettings();

@@ -2188,8 +2357,8 @@ async function getAvailableModels(
    if (match) {
      currentModel = match;
    }
-  } else if (settings.model) {
-    const match = resolveModelPreference(models, settings.model);
+  } else {
+    const match = resolveSettingsModel(models, settings.model, logger);
    if (match) {
      currentModel = match;
    }
@@ -2434,8 +2603,18 @@ export function toAcpNotifications(
              onPostToolUseHook: async (toolUseId, toolInput, toolResponse) => {
                const toolUse = toolUseCache[toolUseId];
                if (toolUse) {
+                  // Both `Edit` and `Write` produce a structuredPatch in their
+                  // PostToolUse tool_response. For Edit the diff replaces the
+                  // optimistic content built at tool_use time. For Write the
+                  // optimistic content (built from `input.content` alone with
+                  // `oldText: null`) shows "creation" semantics regardless of
+                  // whether the file existed; the structuredPatch from the
+                  // hook lets us emit the real diff for `type: "update"`. The
+                  // helper returns `{}` if the response shape isn't usable.
                  const editDiff =
-                    toolUse.name === "Edit" ? toolUpdateFromEditToolResponse(toolResponse) : {};
+                    toolUse.name === "Edit" || toolUse.name === "Write"
+                      ? toolUpdateFromDiffToolResponse(toolResponse)
+                      : {};
                  const update: SessionNotification["update"] = {
                    _meta: {
                      claudeCode: {
--- a/src/tests/acp-agent-settings.test.ts
+++ b/src/tests/acp-agent-settings.test.ts
@@ -39,7 +39,7 @@ describe("ClaudeAcpAgent settings", () => {
        initializationResult: async () => ({
          models: [
            {
-              value: "claude-sonnet-4-5",
+              value: "claude-sonnet-4-6",
              displayName: "Claude Sonnet 4.5",
              description: "Default",
            },
@@ -145,12 +145,12 @@ describe("ClaudeAcpAgent settings", () => {
    expect(response.modes.currentModeId).toBe("default");
  });

-  it("throws when permissions.defaultMode is not a string", async () => {
+  it("falls back to 'default' when permissions.defaultMode is invalid", async () => {
    await fs.promises.writeFile(
      path.join(tempDir, "settings.json"),
      JSON.stringify({
        permissions: {
-          defaultMode: 123,
+          defaultMode: "not-a-real-mode",
        },
      }),
    );
@@ -158,18 +158,208 @@ describe("ClaudeAcpAgent settings", () => {
    const projectDir = path.join(tempDir, "project");
    await fs.promises.mkdir(projectDir, { recursive: true });

-    mockQuery();
+    const { getCapturedOptions } = mockQuery();

    const { ClaudeAcpAgent } = await import("../acp-agent.js");
    const agent: ClaudeAcpAgentType = new ClaudeAcpAgent(createMockClient());

-    await expect(
-      (agent as any).createSession({
+    const response = await (agent as any).createSession({
+      cwd: projectDir,
+      mcpServers: [],
+      _meta: { disableBuiltInTools: true },
+    });
+
+    // Bad mode is ignored at the usage site; session creation must not throw.
+    expect(getCapturedOptions().permissionMode).toBe("default");
+    expect(response.modes.currentModeId).toBe("default");
+  });
+
+  it("ignores model from settings when it is not a string", async () => {
+    await fs.promises.writeFile(
+      path.join(tempDir, "settings.json"),
+      JSON.stringify({
+        model: 123,
+      }),
+    );
+
+    const projectDir = path.join(tempDir, "project");
+    await fs.promises.mkdir(projectDir, { recursive: true });
+
+    const { setModelSpy } = mockQuery();
+
+    const { ClaudeAcpAgent } = await import("../acp-agent.js");
+    const agent: ClaudeAcpAgentType = new ClaudeAcpAgent(createMockClient());
+
+    const response = await (agent as any).createSession({
+      cwd: projectDir,
+      mcpServers: [],
+      _meta: { disableBuiltInTools: true },
+    });
+
+    // Bad model is ignored at the usage site; falls back to the first SDK model.
+    expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-6");
+    expect(response.models.currentModelId).toBe("claude-sonnet-4-6");
+  });
+
+  describe("auto mode availability per model", () => {
+    function mockQueryWithModels(models: any[]): {
+      getCapturedOptions: () => any;
+      setModelSpy: ReturnType<typeof vi.fn>;
+      setPermissionModeSpy: ReturnType<typeof vi.fn>;
+    } {
+      let capturedOptions: any;
+      const setModelSpy = vi.fn();
+      const setPermissionModeSpy = vi.fn();
+      querySpy.mockImplementation(({ options }: any) => {
+        capturedOptions = options;
+        return {
+          initializationResult: async () => ({ models }),
+          setModel: setModelSpy,
+          setPermissionMode: setPermissionModeSpy,
+          supportedCommands: async () => [],
+        } as any;
+      });
+      return {
+        getCapturedOptions: () => capturedOptions,
+        setModelSpy,
+        setPermissionModeSpy,
+      };
+    }
+
+    it("omits `auto` from availableModes when the resolved model lacks supportsAutoMode", async () => {
+      const projectDir = path.join(tempDir, "project");
+      await fs.promises.mkdir(projectDir, { recursive: true });
+
+      mockQueryWithModels([
+        {
+          value: "claude-haiku-4-5",
+          displayName: "Claude Haiku",
+          description: "Fast",
+          // supportsAutoMode intentionally omitted
+        },
+      ]);
+
+      const { ClaudeAcpAgent } = await import("../acp-agent.js");
+      const agent: ClaudeAcpAgentType = new ClaudeAcpAgent(createMockClient());
+
+      const response = await (agent as any).createSession({
        cwd: projectDir,
        mcpServers: [],
        _meta: { disableBuiltInTools: true },
-      }),
-    ).rejects.toThrow("Invalid permissions.defaultMode");
+      });
+
+      const modeIds: string[] = response.modes.availableModes.map((m: any) => m.id);
+      expect(modeIds).not.toContain("auto");
+      expect(modeIds).toEqual(
+        expect.arrayContaining(["default", "acceptEdits", "plan", "dontAsk"]),
+      );
+    });
+
+    it("includes `auto` when the resolved model has supportsAutoMode: true", async () => {
+      const projectDir = path.join(tempDir, "project");
+      await fs.promises.mkdir(projectDir, { recursive: true });
+
+      mockQueryWithModels([
+        {
+          value: "claude-opus-4-5",
+          displayName: "Claude Opus",
+          description: "Most capable",
+          supportsAutoMode: true,
+        },
+      ]);
+
+      const { ClaudeAcpAgent } = await import("../acp-agent.js");
+      const agent: ClaudeAcpAgentType = new ClaudeAcpAgent(createMockClient());
+
+      const response = await (agent as any).createSession({
+        cwd: projectDir,
+        mcpServers: [],
+        _meta: { disableBuiltInTools: true },
+      });
+
+      const modeIds: string[] = response.modes.availableModes.map((m: any) => m.id);
+      expect(modeIds).toContain("auto");
+    });
+
+    it("clamps permissions.defaultMode='auto' to 'default' on a model that lacks supportsAutoMode", async () => {
+      await fs.promises.writeFile(
+        path.join(tempDir, "settings.json"),
+        JSON.stringify({ permissions: { defaultMode: "auto" } }),
+      );
+
+      const projectDir = path.join(tempDir, "project");
+      await fs.promises.mkdir(projectDir, { recursive: true });
+
+      const { getCapturedOptions, setPermissionModeSpy } = mockQueryWithModels([
+        {
+          value: "claude-haiku-4-5",
+          displayName: "Claude Haiku",
+          description: "Fast",
+          // supportsAutoMode intentionally omitted
+        },
+      ]);
+
+      const errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+
+      try {
+        const { ClaudeAcpAgent } = await import("../acp-agent.js");
+        const agent: ClaudeAcpAgentType = new ClaudeAcpAgent(createMockClient());
+
+        const response = await (agent as any).createSession({
+          cwd: projectDir,
+          mcpServers: [],
+          _meta: { disableBuiltInTools: true },
+        });
+
+        // Options.permissionMode is built before init resolves, so it still
+        // carries the user-typed value; the SDK was synced via
+        // setPermissionMode after we discovered the model can't honor it.
+        expect(getCapturedOptions().permissionMode).toBe("auto");
+        expect(setPermissionModeSpy).toHaveBeenCalledWith("default");
+        expect(response.modes.currentModeId).toBe("default");
+        expect(response.modes.availableModes.map((m: any) => m.id)).not.toContain("auto");
+
+        // A descriptive warning was logged so operators see the clamp.
+        const messages = errorSpy.mock.calls.map((c) => c.join(" "));
+        expect(messages.some((m) => m.includes("auto") && m.includes("claude-haiku-4-5"))).toBe(
+          true,
+        );
+      } finally {
+        errorSpy.mockRestore();
+      }
+    });
+
+    it("does not clamp permissions.defaultMode='auto' on a model that supports auto", async () => {
+      await fs.promises.writeFile(
+        path.join(tempDir, "settings.json"),
+        JSON.stringify({ permissions: { defaultMode: "auto" } }),
+      );
+
+      const projectDir = path.join(tempDir, "project");
+      await fs.promises.mkdir(projectDir, { recursive: true });
+
+      const { getCapturedOptions, setPermissionModeSpy } = mockQueryWithModels([
+        {
+          value: "claude-opus-4-5",
+          displayName: "Claude Opus",
+          description: "Most capable",
+          supportsAutoMode: true,
+        },
+      ]);
+
+      const { ClaudeAcpAgent } = await import("../acp-agent.js");
+      const agent: ClaudeAcpAgentType = new ClaudeAcpAgent(createMockClient());
+
+      const response = await (agent as any).createSession({
+        cwd: projectDir,
+        mcpServers: [],
+        _meta: { disableBuiltInTools: true },
+      });
+
+      expect(getCapturedOptions().permissionMode).toBe("auto");
+      expect(setPermissionModeSpy).not.toHaveBeenCalled();
+      expect(response.modes.currentModeId).toBe("auto");
+    });
  });

  it("resolves model aliases like opus[1m] to the correct model", async () => {
--- a/src/tests/acp-agent.test.ts
+++ b/src/tests/acp-agent.test.ts
@@ -22,7 +22,7 @@ import {
  toolInfoFromToolUse,
  toDisplayPath,
  toolUpdateFromToolResult,
-  toolUpdateFromEditToolResponse,
+  toolUpdateFromDiffToolResponse,
 } from "../tools.js";
 import {
  toAcpNotifications,
@@ -998,17 +998,17 @@ describe("toDisplayPath", () => {
  });
 });

-describe("toolUpdateFromEditToolResponse", () => {
+describe("toolUpdateFromDiffToolResponse", () => {
  it("should return empty for non-object input", () => {
-    expect(toolUpdateFromEditToolResponse(null)).toEqual({});
-    expect(toolUpdateFromEditToolResponse(undefined)).toEqual({});
-    expect(toolUpdateFromEditToolResponse("string")).toEqual({});
+    expect(toolUpdateFromDiffToolResponse(null)).toEqual({});
+    expect(toolUpdateFromDiffToolResponse(undefined)).toEqual({});
+    expect(toolUpdateFromDiffToolResponse("string")).toEqual({});
  });

  it("should return empty when filePath or structuredPatch is missing", () => {
-    expect(toolUpdateFromEditToolResponse({})).toEqual({});
-    expect(toolUpdateFromEditToolResponse({ filePath: "/foo.ts" })).toEqual({});
-    expect(toolUpdateFromEditToolResponse({ structuredPatch: [] })).toEqual({});
+    expect(toolUpdateFromDiffToolResponse({})).toEqual({});
+    expect(toolUpdateFromDiffToolResponse({ filePath: "/foo.ts" })).toEqual({});
+    expect(toolUpdateFromDiffToolResponse({ structuredPatch: [] })).toEqual({});
  });

  it("should build diff content from a single-hunk structuredPatch", () => {
@@ -1025,7 +1025,7 @@ describe("toolUpdateFromEditToolResponse", () => {
      ],
    };

-    expect(toolUpdateFromEditToolResponse(toolResponse)).toEqual({
+    expect(toolUpdateFromDiffToolResponse(toolResponse)).toEqual({
      content: [
        {
          type: "diff",
@@ -1059,7 +1059,7 @@ describe("toolUpdateFromEditToolResponse", () => {
      ],
    };

-    expect(toolUpdateFromEditToolResponse(toolResponse)).toEqual({
+    expect(toolUpdateFromDiffToolResponse(toolResponse)).toEqual({
      content: [
        {
          type: "diff",
@@ -1095,7 +1095,7 @@ describe("toolUpdateFromEditToolResponse", () => {
      ],
    };

-    expect(toolUpdateFromEditToolResponse(toolResponse)).toEqual({
+    expect(toolUpdateFromDiffToolResponse(toolResponse)).toEqual({
      content: [
        {
          type: "diff",
@@ -1114,7 +1114,7 @@ describe("toolUpdateFromEditToolResponse", () => {
      structuredPatch: [],
    };

-    expect(toolUpdateFromEditToolResponse(toolResponse)).toEqual({});
+    expect(toolUpdateFromDiffToolResponse(toolResponse)).toEqual({});
  });
 });

@@ -2502,7 +2502,12 @@ describe("usage_update computation", () => {
    const session = agent.sessions["test-session"];
    expect(session.contextWindowSize).toBe(200000);

-    await (agent as any).applyConfigOptionValue(session, "model", "claude-opus-4-6-1m");
+    await (agent as any).applyConfigOptionValue(
+      "test-session",
+      session,
+      "model",
+      "claude-opus-4-6-1m",
+    );
    expect(session.contextWindowSize).toBe(1000000);

    await agent.prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "test" }] });
@@ -2587,7 +2592,12 @@ describe("usage_update computation", () => {
    session.models = { ...session.models, currentModelId: "claude-opus-4-6-1m" };

    // User flips the selector to a 200k model.
-    await (agent as any).applyConfigOptionValue(session, "model", "claude-sonnet-4-6");
+    await (agent as any).applyConfigOptionValue(
+      "test-session",
+      session,
+      "model",
+      "claude-sonnet-4-6",
+    );

    await agent.prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "test" }] });

--- a/src/tests/additional-roots.test.ts
+++ b/src/tests/additional-roots.test.ts
@@ -15,9 +15,17 @@ vi.mock("@anthropic-ai/claude-agent-sdk", async () => ({
    capturedOptions = options;
    return {
      initializationResult: async () => ({
-        models: [{ value: "claude-sonnet-4-5", displayName: "Claude Sonnet", description: "Fast" }],
+        models: [
+          {
+            value: "claude-sonnet-4-6",
+            displayName: "Claude Sonnet",
+            description: "Fast",
+            supportsAutoMode: true,
+          },
+        ],
      }),
      setModel: async () => {},
+      setPermissionMode: async () => {},
      supportedCommands: async () => [],
      [Symbol.asyncIterator]: async function* () {},
    };
--- a/src/tests/authorization.test.ts
+++ b/src/tests/authorization.test.ts
@@ -5,9 +5,12 @@ import { AgentSideConnection } from "@agentclientprotocol/sdk";
 const mockQuery = vi.hoisted(() =>
  vi.fn(() => ({
    initializationResult: vi.fn().mockResolvedValue({
-      models: [{ value: "id", displayName: "name", description: "description" }],
+      models: [
+        { value: "id", displayName: "name", description: "description", supportsAutoMode: true },
+      ],
    }),
    setModel: vi.fn(),
+    setPermissionMode: vi.fn(),
    supportedCommands: vi.fn().mockResolvedValue([]),
  })),
 );
--- a/src/tests/create-session-options.test.ts
+++ b/src/tests/create-session-options.test.ts
@@ -15,10 +15,16 @@ vi.mock("@anthropic-ai/claude-agent-sdk", async () => {
      return {
        initializationResult: async () => ({
          models: [
-            { value: "claude-sonnet-4-5", displayName: "Claude Sonnet", description: "Fast" },
+            {
+              value: "claude-sonnet-4-6",
+              displayName: "Claude Sonnet",
+              description: "Fast",
+              supportsAutoMode: true,
+            },
          ],
        }),
        setModel: async () => {},
+        setPermissionMode: async () => {},
        supportedCommands: async () => [],
        [Symbol.asyncIterator]: async function* () {},
      };
@@ -414,7 +420,7 @@ describe("createSession options merging", () => {
          claudeCode: {
            options: {
              settings: {
-                model: "claude-sonnet-4-5",
+                model: "claude-sonnet-4-6",
                modelOverrides: { "claude-opus-4-6": "meta-value" },
              },
            },
@@ -424,7 +430,7 @@ describe("createSession options merging", () => {

      // _meta settings take precedence; env var is ignored entirely
      expect(capturedOptions!.settings).toEqual({
-        model: "claude-sonnet-4-5",
+        model: "claude-sonnet-4-6",
        modelOverrides: { "claude-opus-4-6": "meta-value" },
      });
    });
--- a/src/tests/resolve-permission-mode.test.ts
+++ b/src/tests/resolve-permission-mode.test.ts
@@ -1,5 +1,12 @@
-import { describe, it, expect } from "vitest";
-import { resolvePermissionMode } from "../acp-agent.js";
+import { describe, it, expect, vi } from "vitest";
+import { resolvePermissionMode, type Logger } from "../acp-agent.js";
+
+function mockLogger() {
+  const error = vi.fn<(...args: any[]) => void>();
+  const log = vi.fn<(...args: any[]) => void>();
+  const logger: Logger = { log, error };
+  return { logger, error, log };
+}

 describe("resolvePermissionMode", () => {
  it("returns 'default' when no mode is provided", () => {
@@ -26,18 +33,25 @@ describe("resolvePermissionMode", () => {
    expect(resolvePermissionMode("  dontAsk  ")).toBe("dontAsk");
  });

-  it("throws on non-string values", () => {
-    expect(() => resolvePermissionMode(123)).toThrow("expected a string");
-    expect(() => resolvePermissionMode(true)).toThrow("expected a string");
-    expect(() => resolvePermissionMode({})).toThrow("expected a string");
+  it("falls back to 'default' and logs on non-string values", () => {
+    for (const value of [123, true, {}]) {
+      const { logger, error } = mockLogger();
+      expect(resolvePermissionMode(value, logger)).toBe("default");
+      expect(error).toHaveBeenCalledWith(expect.stringContaining("expected a string"));
+    }
  });

-  it("throws on empty string", () => {
-    expect(() => resolvePermissionMode("")).toThrow("expected a non-empty string");
-    expect(() => resolvePermissionMode("  ")).toThrow("expected a non-empty string");
+  it("falls back to 'default' and logs on empty string", () => {
+    for (const value of ["", "  "]) {
+      const { logger, error } = mockLogger();
+      expect(resolvePermissionMode(value, logger)).toBe("default");
+      expect(error).toHaveBeenCalledWith(expect.stringContaining("expected a non-empty string"));
+    }
  });

-  it("throws on unknown mode", () => {
-    expect(() => resolvePermissionMode("yolo")).toThrow("Invalid permissions.defaultMode: yolo");
+  it("falls back to 'default' and logs on unknown mode", () => {
+    const { logger, error } = mockLogger();
+    expect(resolvePermissionMode("yolo", logger)).toBe("default");
+    expect(error).toHaveBeenCalledWith(expect.stringContaining("yolo"));
  });
 });
--- a/src/tests/session-config-options.test.ts
+++ b/src/tests/session-config-options.test.ts
@@ -30,7 +30,7 @@ const MOCK_MODELS = {
  currentModelId: "claude-opus-4-5",
  availableModels: [
    { modelId: "claude-opus-4-5", name: "Claude Opus", description: "Most capable" },
-    { modelId: "claude-sonnet-4-5", name: "Claude Sonnet", description: "Balanced" },
+    { modelId: "claude-sonnet-4-6", name: "Claude Sonnet", description: "Balanced" },
  ],
 };

@@ -242,10 +242,10 @@ describe("session config options", () => {
      await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

-      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-5");
+      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-6");

      const configUpdate = sessionUpdates.find(
        (n) => n.update.sessionUpdate === "config_option_update",
@@ -273,7 +273,7 @@ describe("session config options", () => {
        value: "sonnet",
      });

-      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-5");
+      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-6");
    });

    it("resolves display name to model ID", async () => {
@@ -283,19 +283,19 @@ describe("session config options", () => {
        value: "Claude Sonnet",
      });

-      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-5");
+      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-6");
    });

    it("still works with exact model ID", async () => {
      const response = await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

-      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-5");
+      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-6");
      const modelOption = response.configOptions.find((o) => o.id === "model");
-      expect(modelOption?.currentValue).toBe("claude-sonnet-4-5");
+      expect(modelOption?.currentValue).toBe("claude-sonnet-4-6");
    });

    it("throws for completely invalid model value", async () => {
@@ -384,7 +384,7 @@ describe("session config options", () => {
    it("sends config_option_update when model is changed via setSessionModel", async () => {
      await agent.unstable_setSessionModel({
        sessionId: SESSION_ID,
-        modelId: "claude-sonnet-4-5",
+        modelId: "claude-sonnet-4-6",
      });

      const configUpdate = sessionUpdates.find(
@@ -394,7 +394,7 @@ describe("session config options", () => {
      expect(configUpdate?.update).toMatchObject({
        sessionUpdate: "config_option_update",
        configOptions: expect.arrayContaining([
-          expect.objectContaining({ id: "model", currentValue: "claude-sonnet-4-5" }),
+          expect.objectContaining({ id: "model", currentValue: "claude-sonnet-4-6" }),
        ]),
      });
    });
@@ -402,7 +402,7 @@ describe("session config options", () => {
    it("updates stored configOptions currentValue when model changes", async () => {
      await agent.unstable_setSessionModel({
        sessionId: SESSION_ID,
-        modelId: "claude-sonnet-4-5",
+        modelId: "claude-sonnet-4-6",
      });

      const session = (
@@ -411,7 +411,7 @@ describe("session config options", () => {
        }
      ).sessions[SESSION_ID];
      const modelOption = session.configOptions.find((o) => o.id === "model");
-      expect(modelOption?.currentValue).toBe("claude-sonnet-4-5");
+      expect(modelOption?.currentValue).toBe("claude-sonnet-4-6");
    });

    it("includes updated effort in config_option_update when model drops effort support", async () => {
@@ -425,7 +425,7 @@ describe("session config options", () => {
          supportedEffortLevels: ["low", "medium", "high"],
        },
        {
-          value: "claude-sonnet-4-5",
+          value: "claude-sonnet-4-6",
          displayName: "Claude Sonnet",
          description: "Balanced",
          supportsEffort: false,
@@ -434,7 +434,7 @@ describe("session config options", () => {

      await agent.unstable_setSessionModel({
        sessionId: SESSION_ID,
-        modelId: "claude-sonnet-4-5",
+        modelId: "claude-sonnet-4-6",
      });

      const configUpdate = sessionUpdates.find(
@@ -463,7 +463,7 @@ describe("session config options", () => {
          supportedEffortLevels: ["low", "medium", "high", "max"],
        },
        {
-          value: "claude-sonnet-4-5",
+          value: "claude-sonnet-4-6",
          displayName: "Claude Sonnet",
          description: "Balanced",
          supportsEffort: true,
@@ -473,7 +473,7 @@ describe("session config options", () => {

      await agent.unstable_setSessionModel({
        sessionId: SESSION_ID,
-        modelId: "claude-sonnet-4-5",
+        modelId: "claude-sonnet-4-6",
      });

      const configUpdate = sessionUpdates.find(
@@ -495,7 +495,7 @@ describe("session config options", () => {

      await agent.unstable_setSessionModel({
        sessionId: SESSION_ID,
-        modelId: "claude-sonnet-4-5",
+        modelId: "claude-sonnet-4-6",
      });

      const configUpdate = sessionUpdates.find(
@@ -532,7 +532,7 @@ describe("session config options", () => {
      await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

      const configUpdates = sessionUpdates.filter(
@@ -622,7 +622,7 @@ describe("session config options", () => {
          supportedEffortLevels: ["low", "medium", "high"],
        },
        {
-          value: "claude-sonnet-4-5",
+          value: "claude-sonnet-4-6",
          displayName: "Claude Sonnet",
          description: "Balanced",
          supportsEffort: false,
@@ -632,7 +632,7 @@ describe("session config options", () => {
      const response = await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

      const effortOption = response.configOptions.find((o) => o.id === "effort");
@@ -650,7 +650,7 @@ describe("session config options", () => {
          supportedEffortLevels: ["low", "medium", "high"],
        },
        {
-          value: "claude-sonnet-4-5",
+          value: "claude-sonnet-4-6",
          displayName: "Claude Sonnet",
          description: "Balanced",
          supportsEffort: false,
@@ -660,7 +660,7 @@ describe("session config options", () => {
      await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

      expect(applyFlagSettingsSpy).toHaveBeenCalledWith({ effortLevel: undefined });
@@ -669,7 +669,7 @@ describe("session config options", () => {
    it("adds effort option when switching to a model that supports effort", async () => {
      const session = (agent as unknown as { sessions: Record<string, any> }).sessions[SESSION_ID];
      // Start with sonnet (no effort) as current
-      session.models = { ...session.models, currentModelId: "claude-sonnet-4-5" };
+      session.models = { ...session.models, currentModelId: "claude-sonnet-4-6" };
      session.modelInfos = [
        {
          value: "claude-opus-4-5",
@@ -679,7 +679,7 @@ describe("session config options", () => {
          supportedEffortLevels: ["low", "medium", "high"],
        },
        {
-          value: "claude-sonnet-4-5",
+          value: "claude-sonnet-4-6",
          displayName: "Claude Sonnet",
          description: "Balanced",
          supportsEffort: false,
@@ -715,7 +715,7 @@ describe("session config options", () => {
          supportedEffortLevels: ["low", "medium", "high", "max"],
        },
        {
-          value: "claude-sonnet-4-5",
+          value: "claude-sonnet-4-6",
          displayName: "Claude Sonnet",
          description: "Balanced",
          supportsEffort: true,
@@ -726,7 +726,7 @@ describe("session config options", () => {
      const response = await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

      const effortOption = response.configOptions.find((o) => o.id === "effort");
@@ -749,7 +749,7 @@ describe("session config options", () => {
      const response = await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

      const effortOption = response.configOptions.find((o) => o.id === "effort");
@@ -778,10 +778,10 @@ describe("session config options", () => {
      await agent.setSessionConfigOption({
        sessionId: SESSION_ID,
        configId: "model",
-        value: "claude-sonnet-4-5",
+        value: "claude-sonnet-4-6",
      });

-      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-5");
+      expect(setModelSpy).toHaveBeenCalledWith("claude-sonnet-4-6");
    });

    it("setSessionMode also syncs configOptions", async () => {
@@ -798,7 +798,7 @@ describe("session config options", () => {
    it("setSessionModel also syncs configOptions", async () => {
      await agent.unstable_setSessionModel({
        sessionId: SESSION_ID,
-        modelId: "claude-sonnet-4-5",
+        modelId: "claude-sonnet-4-6",
      });

      const session = (
@@ -807,8 +807,395 @@ describe("session config options", () => {
        }
      ).sessions[SESSION_ID];
      expect(session.configOptions.find((o) => o.id === "model")?.currentValue).toBe(
-        "claude-sonnet-4-5",
+        "claude-sonnet-4-6",
      );
    });
  });
+
+  describe("auto mode availability per model", () => {
+    /**
+     * Augment the session populated by `populateSession()` with a Haiku entry
+     * (no `supportsAutoMode`), Opus + Sonnet entries with `supportsAutoMode:
+     * true`, and seed `availableModes` so it currently includes `auto`. This
+     * exercises the per-model recomputation done by `applyConfigOptionValue`
+     * on a model switch.
+     */
+    function setupHaikuOpusSession(currentModeId: string = "default") {
+      const session = (agent as unknown as { sessions: Record<string, any> }).sessions[SESSION_ID];
+      session.modelInfos = [
+        {
+          value: "claude-opus-4-5",
+          displayName: "Claude Opus",
+          description: "Most capable",
+          supportsEffort: true,
+          supportedEffortLevels: ["low", "medium", "high"],
+          supportsAutoMode: true,
+        },
+        {
+          value: "claude-sonnet-4-6",
+          displayName: "Claude Sonnet",
+          description: "Balanced",
+          supportsEffort: true,
+          supportedEffortLevels: ["low", "medium", "high"],
+          supportsAutoMode: true,
+        },
+        {
+          value: "claude-haiku-4-5",
+          displayName: "Claude Haiku",
+          description: "Fast",
+          supportsEffort: true,
+          supportedEffortLevels: ["low", "medium", "high"],
+          // supportsAutoMode intentionally omitted
+        },
+      ];
+      session.models = {
+        currentModelId: "claude-opus-4-5",
+        availableModels: [
+          { modelId: "claude-opus-4-5", name: "Claude Opus", description: "Most capable" },
+          { modelId: "claude-sonnet-4-6", name: "Claude Sonnet", description: "Balanced" },
+          { modelId: "claude-haiku-4-5", name: "Claude Haiku", description: "Fast" },
+        ],
+      };
+      session.modes = {
+        currentModeId,
+        availableModes: [
+          {
+            id: "auto",
+            name: "Auto",
+            description: "Use a model classifier to approve/deny permission prompts",
+          },
+          {
+            id: "default",
+            name: "Default",
+            description: "Standard behavior, prompts for dangerous operations",
+          },
+          {
+            id: "acceptEdits",
+            name: "Accept Edits",
+            description: "Auto-accept file edit operations",
+          },
+          { id: "plan", name: "Plan Mode", description: "Planning mode" },
+          {
+            id: "dontAsk",
+            name: "Don't Ask",
+            description: "Don't prompt for permissions, deny if not pre-approved",
+          },
+        ],
+      };
+      // Reflect the seeded availableModes/availableModels in configOptions so
+      // the pre-state matches what `createSession` would have produced for
+      // Opus, and `setSessionConfigOption` validation can accept the seeded
+      // model ids (notably the new Haiku entry).
+      session.configOptions = session.configOptions.map((o: any) => {
+        if (o.id === "mode") {
+          return {
+            ...o,
+            currentValue: currentModeId,
+            options: session.modes.availableModes.map((m: any) => ({
+              value: m.id,
+              name: m.name,
+              description: m.description,
+            })),
+          };
+        }
+        if (o.id === "model") {
+          return {
+            ...o,
+            currentValue: session.models.currentModelId,
+            options: session.models.availableModels.map((m: any) => ({
+              value: m.modelId,
+              name: m.name,
+              description: m.description,
+            })),
+          };
+        }
+        return o;
+      });
+      return session;
+    }
+
+    beforeEach(() => {
+      populateSession();
+    });
+
+    it("drops `auto` from available modes when switching to Haiku", async () => {
+      setupHaikuOpusSession("default");
+
+      await agent.unstable_setSessionModel({
+        sessionId: SESSION_ID,
+        modelId: "claude-haiku-4-5",
+      });
+
+      const configUpdate = sessionUpdates.find(
+        (n) => n.update.sessionUpdate === "config_option_update",
+      );
+      expect(configUpdate).toBeDefined();
+      const modeOption = (configUpdate?.update as any).configOptions.find(
+        (o: any) => o.id === "mode",
+      );
+      expect(modeOption).toBeDefined();
+      const modeValues = modeOption.options.map((o: any) => o.value);
+      expect(modeValues).not.toContain("auto");
+      expect(modeValues).toEqual(
+        expect.arrayContaining(["default", "acceptEdits", "plan", "dontAsk"]),
+      );
+    });
+
+    it("clamps to `default` and emits current_mode_update when Opus(auto) → Haiku", async () => {
+      setupHaikuOpusSession("auto");
+
+      await agent.unstable_setSessionModel({
+        sessionId: SESSION_ID,
+        modelId: "claude-haiku-4-5",
+      });
+
+      // SDK was synced to "default".
+      expect(setPermissionModeSpy).toHaveBeenCalledWith("default");
+
+      // current_mode_update was emitted before config_option_update so a
+      // client applying notifications in order observes the mode change
+      // before re-rendering the config-option list.
+      const modeUpdateIdx = sessionUpdates.findIndex(
+        (n) => n.update.sessionUpdate === "current_mode_update",
+      );
+      const configUpdateIdx = sessionUpdates.findIndex(
+        (n) => n.update.sessionUpdate === "config_option_update",
+      );
+      expect(modeUpdateIdx).toBeGreaterThanOrEqual(0);
+      expect(configUpdateIdx).toBeGreaterThanOrEqual(0);
+      expect(modeUpdateIdx).toBeLessThan(configUpdateIdx);
+      expect((sessionUpdates[modeUpdateIdx].update as any).currentModeId).toBe("default");
+
+      // configOptions reflect the clamped mode.
+      const modeOption = (sessionUpdates[configUpdateIdx].update as any).configOptions.find(
+        (o: any) => o.id === "mode",
+      );
+      expect(modeOption.currentValue).toBe("default");
+    });
+
+    it("re-adds `auto` when switching from Haiku back to Opus", async () => {
+      const session = setupHaikuOpusSession("default");
+      // Pretend Haiku is the current model with no `auto`.
+      session.models.currentModelId = "claude-haiku-4-5";
+      session.modes.availableModes = session.modes.availableModes.filter(
+        (m: any) => m.id !== "auto",
+      );
+      const modeOpt = session.configOptions.find((o: any) => o.id === "mode");
+      modeOpt.options = session.modes.availableModes.map((m: any) => ({
+        value: m.id,
+        name: m.name,
+        description: m.description,
+      }));
+
+      await agent.unstable_setSessionModel({
+        sessionId: SESSION_ID,
+        modelId: "claude-opus-4-5",
+      });
+
+      const configUpdate = sessionUpdates.find(
+        (n) => n.update.sessionUpdate === "config_option_update",
+      );
+      expect(configUpdate).toBeDefined();
+      const modeOption = (configUpdate?.update as any).configOptions.find(
+        (o: any) => o.id === "mode",
+      );
+      const modeValues = modeOption.options.map((o: any) => o.value);
+      expect(modeValues).toContain("auto");
+
+      // The current mode ("default") is still valid on Opus, so no
+      // current_mode_update should have been emitted by the model switch.
+      const modeUpdates = sessionUpdates.filter(
+        (n) => n.update.sessionUpdate === "current_mode_update",
+      );
+      expect(modeUpdates).toHaveLength(0);
+    });
+
+    it("preserves the current mode when it remains valid after a model switch", async () => {
+      setupHaikuOpusSession("plan");
+
+      await agent.unstable_setSessionModel({
+        sessionId: SESSION_ID,
+        modelId: "claude-haiku-4-5",
+      });
+
+      // `plan` is in availableModes for both Opus and Haiku, so no clamp.
+      expect(setPermissionModeSpy).not.toHaveBeenCalledWith("default");
+
+      const modeUpdates = sessionUpdates.filter(
+        (n) => n.update.sessionUpdate === "current_mode_update",
+      );
+      expect(modeUpdates).toHaveLength(0);
+
+      const configUpdate = sessionUpdates.find(
+        (n) => n.update.sessionUpdate === "config_option_update",
+      );
+      const modeOption = (configUpdate?.update as any).configOptions.find(
+        (o: any) => o.id === "mode",
+      );
+      expect(modeOption.currentValue).toBe("plan");
+    });
+
+    it("clamps mode and emits current_mode_update via setSessionConfigOption(model)", async () => {
+      // Mirrors the unstable_setSessionModel(auto → Haiku) test, but goes
+      // through the request/response API. The `current_mode_update` side
+      // effect must still fire so clients learn about the clamp regardless of
+      // which entry point triggered the model switch.
+      setupHaikuOpusSession("auto");
+
+      const response = await agent.setSessionConfigOption({
+        sessionId: SESSION_ID,
+        configId: "model",
+        value: "claude-haiku-4-5",
+      });
+
+      expect(setPermissionModeSpy).toHaveBeenCalledWith("default");
+
+      const modeUpdates = sessionUpdates.filter(
+        (n) => n.update.sessionUpdate === "current_mode_update",
+      );
+      expect(modeUpdates).toHaveLength(1);
+      expect((modeUpdates[0].update as any).currentModeId).toBe("default");
+
+      // setSessionConfigOption is a request/response API: it returns the new
+      // configOptions in the response rather than emitting a
+      // config_option_update notification.
+      const configUpdates = sessionUpdates.filter(
+        (n) => n.update.sessionUpdate === "config_option_update",
+      );
+      expect(configUpdates).toHaveLength(0);
+
+      const modeOption = response.configOptions.find((o: any) => o.id === "mode");
+      expect(modeOption).toBeDefined();
+      expect((modeOption as any).currentValue).toBe("default");
+      expect((modeOption as any).options.map((o: any) => o.value)).not.toContain("auto");
+    });
+
+    it("rejects direct setSessionMode to `auto` when the active model does not offer it", async () => {
+      const session = setupHaikuOpusSession("default");
+      session.models.currentModelId = "claude-haiku-4-5";
+      session.modes.availableModes = session.modes.availableModes.filter(
+        (mode: any) => mode.id !== "auto",
+      );
+
+      await expect(agent.setSessionMode({ sessionId: SESSION_ID, modeId: "auto" })).rejects.toThrow(
+        "Mode auto is not available in this session",
+      );
+
+      expect(setPermissionModeSpy).not.toHaveBeenCalledWith("auto");
+      expect(sessionUpdates).toHaveLength(0);
+    });
+  });
+
+  describe("ExitPlanMode permission options filtered by availableModes", () => {
+    let capturedPermissionRequest: any;
+    let permissionResponse: any;
+
+    beforeEach(() => {
+      capturedPermissionRequest = null;
+      permissionResponse = { outcome: { outcome: "cancelled" } };
+      // Replace the default mock client with one that captures the
+      // requestPermission call so we can assert on the offered options.
+      (agent as any).client = {
+        sessionUpdate: async (notification: SessionNotification) => {
+          sessionUpdates.push(notification);
+        },
+        requestPermission: async (params: any) => {
+          capturedPermissionRequest = params;
+          return permissionResponse;
+        },
+        readTextFile: async () => ({ content: "" }),
+        writeTextFile: async () => ({}),
+      };
+      populateSession();
+    });
+
+    it("omits the `auto` option on a model without supportsAutoMode", async () => {
+      const session = (agent as unknown as { sessions: Record<string, any> }).sessions[SESSION_ID];
+      // Haiku-shaped session: availableModes does NOT include `auto`.
+      session.modes = {
+        currentModeId: "plan",
+        availableModes: [
+          { id: "default", name: "Default", description: "Standard" },
+          { id: "acceptEdits", name: "Accept Edits", description: "Auto-accept edits" },
+          { id: "plan", name: "Plan Mode", description: "Planning mode" },
+          { id: "dontAsk", name: "Don't Ask", description: "Deny if not pre-approved" },
+        ],
+      };
+
+      const canUseTool = (agent as any).canUseTool(SESSION_ID);
+      const signal = new AbortController().signal;
+      try {
+        await canUseTool(
+          "ExitPlanMode",
+          { plan: "do stuff" },
+          { signal, suggestions: undefined, toolUseID: "toolu_1" },
+        );
+      } catch {
+        // The mock client returns `cancelled`, which makes canUseTool throw.
+        // We only care about the captured requestPermission options.
+      }
+
+      expect(capturedPermissionRequest).not.toBeNull();
+      const optionIds = capturedPermissionRequest.options.map((o: any) => o.optionId);
+      expect(optionIds).not.toContain("auto");
+      expect(optionIds).toEqual(expect.arrayContaining(["default", "acceptEdits", "plan"]));
+    });
+
+    it("denies a selected `auto` option if the client did not receive that option", async () => {
+      const session = (agent as unknown as { sessions: Record<string, any> }).sessions[SESSION_ID];
+      session.modes = {
+        currentModeId: "plan",
+        availableModes: [
+          { id: "default", name: "Default", description: "Standard" },
+          { id: "acceptEdits", name: "Accept Edits", description: "Auto-accept edits" },
+          { id: "plan", name: "Plan Mode", description: "Planning mode" },
+          { id: "dontAsk", name: "Don't Ask", description: "Deny if not pre-approved" },
+        ],
+      };
+      permissionResponse = { outcome: { outcome: "selected", optionId: "auto" } };
+
+      const canUseTool = (agent as any).canUseTool(SESSION_ID);
+      const result = await canUseTool(
+        "ExitPlanMode",
+        { plan: "do stuff" },
+        { signal: new AbortController().signal, suggestions: undefined, toolUseID: "toolu_2" },
+      );
+
+      expect(capturedPermissionRequest).not.toBeNull();
+      const optionIds = capturedPermissionRequest.options.map((o: any) => o.optionId);
+      expect(optionIds).not.toContain("auto");
+      expect(result.behavior).toBe("deny");
+      expect(sessionUpdates).toHaveLength(0);
+    });
+
+    it("includes the `auto` option on a model with supportsAutoMode", async () => {
+      const session = (agent as unknown as { sessions: Record<string, any> }).sessions[SESSION_ID];
+      session.modes = {
+        currentModeId: "plan",
+        availableModes: [
+          { id: "auto", name: "Auto", description: "Use a model classifier" },
+          { id: "default", name: "Default", description: "Standard" },
+          { id: "acceptEdits", name: "Accept Edits", description: "Auto-accept edits" },
+          { id: "plan", name: "Plan Mode", description: "Planning mode" },
+          { id: "dontAsk", name: "Don't Ask", description: "Deny if not pre-approved" },
+        ],
+      };
+
+      const canUseTool = (agent as any).canUseTool(SESSION_ID);
+      const signal = new AbortController().signal;
+      try {
+        await canUseTool(
+          "ExitPlanMode",
+          { plan: "do stuff" },
+          { signal, suggestions: undefined, toolUseID: "toolu_3" },
+        );
+      } catch {
+        // mock returns cancelled
+      }
+
+      expect(capturedPermissionRequest).not.toBeNull();
+      const optionIds = capturedPermissionRequest.options.map((o: any) => o.optionId);
+      expect(optionIds).toContain("auto");
+    });
+  });
 });
--- a/src/tests/tools.test.ts
+++ b/src/tests/tools.test.ts
@@ -1056,6 +1056,162 @@ describe("Bash terminal output", () => {
    });
  });

+  describe("post-tool-use hook sends diff content for Write tool", () => {
+    // Regression: previously the dispatch only invoked
+    // toolUpdateFromDiffToolResponse for `Edit`, so a Write that
+    // overwrote an existing file (FileWriteOutput.type === "update")
+    // showed a "creation" diff (oldText: null, full new content) at
+    // tool_use time and was never corrected after the tool ran.
+    it("should emit a real diff for Write of an existing file (type: update)", async () => {
+      const toolUseCache: ToolUseCache = {};
+      const hookUpdates: any[] = [];
+      const mockClientWithUpdate = {
+        sessionUpdate: async (notification: any) => {
+          hookUpdates.push(notification);
+        },
+      } as unknown as AgentSideConnection;
+
+      toAcpNotifications(
+        [
+          {
+            type: "tool_use" as const,
+            id: "toolu_write_update",
+            name: "Write",
+            input: {
+              file_path: "/Users/test/project/file.ts",
+              content: "line1\nNEW line2\nline3",
+            },
+          },
+        ],
+        "assistant",
+        "test-session",
+        toolUseCache,
+        mockClientWithUpdate,
+        mockLogger,
+      );
+
+      const hook = createPostToolUseHook(mockLogger);
+      await hook(
+        {
+          hook_event_name: "PostToolUse",
+          tool_name: "Write",
+          tool_input: {
+            file_path: "/Users/test/project/file.ts",
+            content: "line1\nNEW line2\nline3",
+          },
+          tool_response: {
+            type: "update",
+            filePath: "/Users/test/project/file.ts",
+            content: "line1\nNEW line2\nline3",
+            originalFile: "line1\nold line2\nline3",
+            structuredPatch: [
+              {
+                oldStart: 1,
+                oldLines: 3,
+                newStart: 1,
+                newLines: 3,
+                lines: [" line1", "-old line2", "+NEW line2", " line3"],
+              },
+            ],
+            userModified: false,
+          },
+          tool_use_id: "toolu_write_update",
+          session_id: "test-session",
+          transcript_path: "/tmp/test",
+          cwd: "/tmp",
+        },
+        "toolu_write_update",
+        { signal: AbortSignal.abort() },
+      );
+
+      expect(hookUpdates).toHaveLength(1);
+      const hookUpdate = hookUpdates[0].update;
+      expect(hookUpdate._meta.claudeCode.toolName).toBe("Write");
+      expect(hookUpdate.content).toEqual([
+        {
+          type: "diff",
+          path: "/Users/test/project/file.ts",
+          oldText: "line1\nold line2\nline3",
+          newText: "line1\nNEW line2\nline3",
+        },
+      ]);
+      expect(hookUpdate.locations).toEqual([{ path: "/Users/test/project/file.ts", line: 1 }]);
+    });
+
+    it("should still emit a sensible diff for Write of a brand-new file (type: create)", async () => {
+      const toolUseCache: ToolUseCache = {};
+      const hookUpdates: any[] = [];
+      const mockClientWithUpdate = {
+        sessionUpdate: async (notification: any) => {
+          hookUpdates.push(notification);
+        },
+      } as unknown as AgentSideConnection;
+
+      toAcpNotifications(
+        [
+          {
+            type: "tool_use" as const,
+            id: "toolu_write_create",
+            name: "Write",
+            input: {
+              file_path: "/Users/test/project/new.ts",
+              content: "first\nsecond",
+            },
+          },
+        ],
+        "assistant",
+        "test-session",
+        toolUseCache,
+        mockClientWithUpdate,
+        mockLogger,
+      );
+
+      const hook = createPostToolUseHook(mockLogger);
+      await hook(
+        {
+          hook_event_name: "PostToolUse",
+          tool_name: "Write",
+          tool_input: {
+            file_path: "/Users/test/project/new.ts",
+            content: "first\nsecond",
+          },
+          tool_response: {
+            type: "create",
+            filePath: "/Users/test/project/new.ts",
+            content: "first\nsecond",
+            originalFile: null,
+            structuredPatch: [
+              {
+                oldStart: 0,
+                oldLines: 0,
+                newStart: 1,
+                newLines: 2,
+                lines: ["+first", "+second"],
+              },
+            ],
+          },
+          tool_use_id: "toolu_write_create",
+          session_id: "test-session",
+          transcript_path: "/tmp/test",
+          cwd: "/tmp",
+        },
+        "toolu_write_create",
+        { signal: AbortSignal.abort() },
+      );
+
+      expect(hookUpdates).toHaveLength(1);
+      const hookUpdate = hookUpdates[0].update;
+      expect(hookUpdate.content).toEqual([
+        {
+          type: "diff",
+          path: "/Users/test/project/new.ts",
+          oldText: null,
+          newText: "first\nsecond",
+        },
+      ]);
+    });
+  });
+
  describe("post-tool-use hook preserves terminal _meta", () => {
    it("should send terminal_output and terminal_exit as separate notifications, and hook should only have claudeCode", async () => {
      const clientCapabilities: ClientCapabilities = {
--- a/src/tools.ts
+++ b/src/tools.ts
@@ -679,7 +679,7 @@ export function markdownEscape(text: string): string {
  return escape + "\n" + text + (text.endsWith("\n") ? "" : "\n") + escape;
 }

-interface EditToolResponseHunk {
+interface DiffToolResponseHunk {
  oldStart: number;
  oldLines: number;
  newStart: number;
@@ -687,23 +687,24 @@ interface EditToolResponseHunk {
  lines: string[];
 }

-interface EditToolResponse {
+interface DiffToolResponse {
  filePath?: string;
-  structuredPatch?: EditToolResponseHunk[];
+  structuredPatch?: DiffToolResponseHunk[];
 }

 /**
- * Builds diff ToolUpdate content from the structured Edit toolResponse provided
- * by the PostToolUse hook. Unlike parsing the plain unified diff string, this uses
- * the pre-parsed structuredPatch which supports multiple replacement sites (replaceAll)
- * and always includes context lines for better readability.
+ * Builds diff ToolUpdate content from the structured toolResponse provided by
+ * the PostToolUse hook for diff-producing tools (Edit, Write). Unlike parsing
+ * the plain unified diff string, this uses the pre-parsed structuredPatch
+ * which supports multiple replacement sites (replaceAll) and always includes
+ * context lines for better readability.
 */
-export function toolUpdateFromEditToolResponse(toolResponse: unknown): {
+export function toolUpdateFromDiffToolResponse(toolResponse: unknown): {
  content?: ToolCallContent[];
  locations?: ToolCallLocation[];
 } {
  if (!toolResponse || typeof toolResponse !== "object") return {};
-  const response = toolResponse as EditToolResponse;
+  const response = toolResponse as DiffToolResponse;
  if (!response.filePath || !Array.isArray(response.structuredPatch)) return {};

  const content: ToolCallContent[] = [];