fix(fs-local): degrade basis I/O failures to null

Descriptor-phase errnos in readTextForDiff fold to before: null so a file deleted or made unreadable after the caller's preflight cannot fail the committed write; cancellation and non-errno faults still propagate. Drops the now-covered isFile v8 ignore, extends llm-replay with catalog capability parity (defaultMaxTokens/reasoningEfforts), and records the fs-write-overwrite-bounded keyless snapshot pinning the over-limit whole-file fallback through the real acp-agent composition.
2026-08-08 11:49:42 -07:00
parent 3f3c8e31e9
commit 9a299f9827
13 changed files with 281 additions and 43 deletions
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/bug-fix/2026-07-30-bounded-overwrite-diff-basis.md
-2026-07-30-bounded-overwrite-diff-basis.md: 353b538a12b8cf48dfa3a561c62d6d8ab9a8bfcf
-2026-07-30-bounded-overwrite-diff-basis.zh.md: e2b473a21d16dc47b5b8bf781b8ddffdf443955b
+2026-07-30-bounded-overwrite-diff-basis.md: 7a09934bd1798059de43a092f338d37aa9ccbd9a
+2026-07-30-bounded-overwrite-diff-basis.zh.md: 1d6bdd1068d119aae859132d9f8216ca29d0dc11
@@ -10,7 +10,7 @@ English | [中文](2026-07-30-bounded-overwrite-diff-basis.zh.md)

 ## Decision

-`LocalFileSystem.Config.diffBasisMaxBytes` is a positive safe-integer deployment setting no greater than the runtime's Buffer-allocation and string-decoding limits, with a 10 MiB default. An overwrite supplies `before` only when the UTF-8 replacement is strictly below that limit and the prior file opened for the basis also ends below it. The prior read opens a descriptor, checks that descriptor, and reads at most the configured byte count in cancellation-aware chunks; reaching the boundary returns `null`. A size change after descriptor stat also returns `null`, even if the final size remains below the limit, because a partial prefix would be an incorrect diff basis. Binary or invalid UTF-8 prior content likewise returns `null`. These outcomes do not block the atomic write.
+`LocalFileSystem.Config.diffBasisMaxBytes` is a positive safe-integer deployment setting no greater than the runtime's Buffer-allocation and string-decoding limits, with a 10 MiB default. An overwrite supplies `before` only when the UTF-8 replacement is strictly below that limit and the prior file opened for the basis also ends below it. The prior read opens a descriptor, checks that descriptor, and reads at most the configured byte count in cancellation-aware chunks; reaching the boundary returns `null`. A size change after descriptor stat also returns `null`, even if the final size remains below the limit, because a partial prefix would be an incorrect diff basis. Binary or invalid UTF-8 prior content likewise returns `null`, as does any descriptor-phase errno — a prior file deleted or made unreadable between the caller's preflight and the basis open cannot fail a write the caller already committed to; only cancellation and non-errno faults propagate. These outcomes do not block the atomic write.

 The local provider owns this decision because `before` is its optional, best-effort basis: it can avoid acquiring prior content that the configured pair limit has already made ineligible. `tool-fs` continues to own diff computation, retention, and presentation. The setting is independent of `tool-fs.readStreamMinSize`; read routing and overwrite presentation are different policies and need not share a value.

@@ -10,7 +10,7 @@ Status: implemented

 ## Decision

-`LocalFileSystem.Config.diffBasisMaxBytes` 是一个不超过运行时 Buffer 分配和字符串解码上限的正安全整数部署配置，默认 10 MiB。只有当 UTF-8 替换内容严格低于该上限，且为生成基础而打开的旧文件最终也低于该上限时，覆写才提供 `before`。旧文件读取会打开文件描述符、检查该描述符，并按可响应取消的分块最多读取配置的字节数；一旦到达边界便返回 `null`。描述符 stat 后发生大小变化时同样返回 `null`，即使最终大小仍低于上限，因为部分前缀会成为错误的 diff 基础。旧内容为二进制或无效 UTF-8 时也返回 `null`。这些结果都不会阻止原子写入。
+`LocalFileSystem.Config.diffBasisMaxBytes` 是一个不超过运行时 Buffer 分配和字符串解码上限的正安全整数部署配置，默认 10 MiB。只有当 UTF-8 替换内容严格低于该上限，且为生成基础而打开的旧文件最终也低于该上限时，覆写才提供 `before`。旧文件读取会打开文件描述符、检查该描述符，并按可响应取消的分块最多读取配置的字节数；一旦到达边界便返回 `null`。描述符 stat 后发生大小变化时同样返回 `null`，即使最终大小仍低于上限，因为部分前缀会成为错误的 diff 基础。旧内容为二进制或无效 UTF-8 时也返回 `null`；描述符阶段的任何 errno 同样如此——旧文件在调用方预检之后、基础读取打开之前被删除或变得不可读，不能让调用方已经提交的写入失败；只有取消和非 errno 故障会继续向上传播。这些结果都不会阻止原子写入。

 本地提供方拥有该决策，因为 `before` 是它提供的可选、尽力而为的基础：当配置的成对上限已使替换内容不合格时，它可以避免获取旧内容。`tool-fs` 继续拥有 diff 计算、保留与展示。该配置独立于 `tool-fs.readStreamMinSize`；读取路由与覆写展示是不同策略，无需共享数值。

@@ -52,6 +52,7 @@ const WEB_CONFIG = fileURLToPath(new URL('../web.cordis.yml', import.meta.url))
 const FS_SEARCH_CONFIG = fileURLToPath(new URL('./fs-search.cordis.yml', import.meta.url))
 const PARTIAL_LANDLOCK_CONFIG = fileURLToPath(new URL('../partial-landlock.cordis.yml', import.meta.url))
 const PWSH_CONFIG = fileURLToPath(new URL('./pwsh.cordis.yml', import.meta.url))
+const FS_DIFF_BOUND_CONFIG = fileURLToPath(new URL('./fs-diff-bound.cordis.yml', import.meta.url))
 const SNAPSHOTS_DIR = join(dirname(fileURLToPath(import.meta.url)), 'snapshots')
 const PACKED_CHUNKS_SOURCE = 'hook-cc-pretool-deny'

@@ -253,6 +254,21 @@ const SCENARIOS: Scenario[] = [
  { name: 'fs-write', hasModelTurn: true, recorded: true },
  { name: 'fs-edit', hasModelTurn: true, recorded: true },
  { name: 'fs-write-overwrite', hasModelTurn: true, recorded: true },
+  // An overwrite whose replacement is at/above the configured diff-basis bound:
+  // the persisted result meta carries no contextual hunks and presentation
+  // falls back to the whole-file diff. The overlay leaves the prompt and tool
+  // sequence identical to text-turn, but the freshly recorded header carries
+  // the current adapter capability fields, so the scenario pins its own class.
+  {
+    name: 'fs-write-overwrite-bounded',
+    hasModelTurn: true,
+    recorded: true,
+    pinsHeader: true,
+    headerClass: 'fs-diff-bound',
+    systemPromptSource: 'text-turn',
+    toolSchemasSource: 'text-turn',
+    configPath: FS_DIFF_BOUND_CONFIG,
+  },
  { name: 'fs-read-window', hasModelTurn: true, recorded: true },
  { name: 'fs-policy-reject', hasModelTurn: true, recorded: true },
  { name: 'multi-turn', hasModelTurn: true, recorded: true },
@@ -0,0 +1,46 @@
+# Keyless replay counterpart to fs-diff-bound.cordis.yml. Replay patches apply
+# directly against the live cordis.yml because include patches cannot target
+# entries behind a nested include; the acp-agent restatement keeps the recorded
+# deepseek-v4-flash model and raw JSONL persistence for the harness's harvest.
+- id: base
+  name: '@cordisjs/plugin-include'
+  config:
+    path: ../cordis.yml
+    patches:
+      - id: llm-deepseek
+        name: '@deepseek-ai/dsh-llm-deepseek'
+        disabled: true
+      - id: acp-agent
+        name: '@deepseek-ai/dsh-acp-demo'
+        config:
+          provider: deepseek-official
+          model: deepseek-v4-flash
+          persistenceRoot: !!js process.env.DSH_SNAPSHOT_SESSIONS_ROOT ?? './.sessions'
+          persistenceCompression: none
+          workspaceContext:
+            maxBytes: 65536
+          persona: |
+            You are a coding assistant powered by the {{model}} model. Your working directory is {{cwd}}. Your bash tool runs under a file sandbox — a `[sandbox: file access denied …]` result is policy, not a command bug.
+
+            Verify your work by running the code or tests. Keep answers brief and factual.
+      - id: fs-sandbox
+        name: '@deepseek-ai/dsh-fs-sandbox'
+        config:
+          cwd: !!js process.cwd()
+          diffBasisMaxBytes: 64
+      - insert:
+          - id: llm-replay
+            name: '@deepseek-ai/dsh-llm-replay'
+            config:
+              providers:
+                - id: deepseek-official
+                  name: DeepSeek
+                  models:
+                    # Capability parity with the live adapter so replay
+                    # reconstructs the freshly recorded request header.
+                    - id: deepseek-v4-flash
+                      contextWindow: 1000000
+                      defaultMaxTokens: 256000
+                      reasoningEfforts: ['off', 'high', 'max']
+                      defaultReasoningEffort: max
+                    - id: deepseek-v4-pro
@@ -0,0 +1,29 @@
+# Live counterpart for the bounded-overwrite-diff snapshot: the base stack with
+# the fs backend's overwrite diff-basis limit shrunk so a modest replacement
+# crosses the exclusive bound and the write result falls back to a whole-file
+# diff. A config patch replaces the row's whole config, so `cwd` is restated
+# verbatim, and the acp-agent restatement re-pins `deepseek-v4-flash` to match
+# the recorded corpus and its pinned request headers.
+- id: base
+  name: '@cordisjs/plugin-include'
+  config:
+    path: ../cordis.yml
+    patches:
+      - id: acp-agent
+        name: '@deepseek-ai/dsh-acp-demo'
+        config:
+          provider: deepseek-official
+          model: deepseek-v4-flash
+          persistenceRoot: !!js process.env.DSH_SNAPSHOT_SESSIONS_ROOT ?? './.sessions'
+          persistenceCompression: !!js "process.env.DSH_SNAPSHOT === undefined ? 'zstd' : 'none'"
+          workspaceContext:
+            maxBytes: 65536
+          persona: |
+            You are a coding assistant powered by the {{model}} model. Your working directory is {{cwd}}. Your bash tool runs under a file sandbox — a `[sandbox: file access denied …]` result is policy, not a command bug.
+
+            Verify your work by running the code or tests. Keep answers brief and factual.
+      - id: fs-sandbox
+        name: '@deepseek-ai/dsh-fs-sandbox'
+        config:
+          cwd: !!js process.cwd()
+          diffBasisMaxBytes: 64
@@ -0,0 +1,7 @@
+{
+  "steps": [
+    { "op": "initialize" },
+    { "op": "newSession" },
+    { "op": "prompt", "text": "First use the read tool to read data.txt in the current directory. Then use the write tool (NOT bash) to replace its entire contents with exactly this single line: The replacement line is deliberately longer than the configured sixty-four byte diff-basis bound. Then reply with exactly the single word DONE." }
+  ]
+}
@@ -0,0 +1,42 @@
+{"type":"session","version":0,"id":"14b14f51-2428-43a0-bcc5-5f392d4faa19","createdAt":1786204699215,"cwd":"{{cwd}}","delegationDepth":0}
+{"type":"agent/inbox/spliced","seq":0,"time":1786204699218,"data":{"target":"next-turn","start":0,"inserted":[{"content":[{"type":"text","text":"First use the read tool to read data.txt in the current directory. Then use the write tool (NOT bash) to replace its entire contents with exactly this single line: The replacement line is deliberately longer than the configured sixty-four byte diff-basis bound. Then reply with exactly the single word DONE."}],"source":{"kind":"user"},"role":"user","id":"41d72cfe-0e37-474f-83dc-2b15bacf9c0d"}]}}
+{"type":"turn/start","seq":1,"time":1786204699219,"data":{"turn":1}}
+{"type":"agent/inbox/spliced","seq":2,"time":1786204699220,"data":{"target":"next-turn","start":0,"removedCount":1,"inserted":[]}}
+{"type":"step/start","seq":3,"time":1786204699259,"data":{"turn":1,"step":1}}
+{"type":"user/message","seq":4,"time":1786204699259,"data":{"content":[{"type":"text","text":"First use the read tool to read data.txt in the current directory. Then use the write tool (NOT bash) to replace its entire contents with exactly this single line: The replacement line is deliberately longer than the configured sixty-four byte diff-basis bound. Then reply with exactly the single word DONE."}],"source":{"kind":"user"},"role":"user","id":"41d72cfe-0e37-474f-83dc-2b15bacf9c0d"},"surfaceOp":"append"}
+{"type":"user/message","seq":5,"time":1786204699260,"data":{"content":[{"type":"text","text":"Current runtime context. This snapshot supersedes earlier runtime-context snapshots.\n\nCurrent DSH file policy: danger-full-access. The DSH file sandbox does not restrict file modifications by available operations.\n\nApproval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`)."}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt","form":"snapshot","sections":[{"name":"sandbox:policy","text":"Current DSH file policy: danger-full-access. The DSH file sandbox does not restrict file modifications by available operations."},{"name":"approval:policy","text":"Approval prompts are disabled in this session: actions that require approval are rejected automatically — do not request sandbox escalation (do not set `sandbox_permissions`)."}]},"role":"user","id":"e374fb32-1cad-4e2d-9cd3-66ac8fcf9588"},"surfaceOp":"append"}
+{"type":"session/title","seq":6,"time":1786204699261,"data":{"title":"First use the read tool","messageSeqs":[4],"source":{"kind":"fallback"}}}
+{"type":"request/header","seq":7,"time":1786204699262,"data":{"header":{"config":{"provider":"deepseek-official","model":"deepseek-v4-flash","maxTokens":256000,"reasoningEffort":"max"},"adapterDefaults":{"reasoningEffort":true,"maxTokens":true},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}
+{"type":"request/context","seq":8,"time":1786204699262,"data":{"provider":"deepseek-official","model":"deepseek-v4-flash","contextWindow":1000000}}
+{"type":"assistant/chunk","seq":9,"time":1786204701601,"data":{"turn":1,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}
+{"type":"reasoning-chunks","seq0":10,"time0":1786204701602,"data":{"turn":1,"step":1,"index":0,"dt":[60,22,2,1,0,1,0,19,2,1,1,17,21,2,0,20,2,1,21,0,0,0,1,21,2],"texts":["The"," user"," wants"," me"," to"," read"," data",".txt"," first",","," then"," write"," to"," replace"," its"," contents"," with"," the"," exact"," line",","," then"," reply"," D","ONE","."]}}
+{"type":"assistant/chunk","seq":36,"time":1786204701863,"data":{"turn":1,"step":1,"chunk":{"type":"block-start","index":1,"blockType":"tool-call"}}}
+{"type":"tool-call-chunks","seq0":37,"time0":1786204701864,"data":{"turn":1,"step":1,"index":1,"dt":[21,2,0,21,2,1,0,26,1,0,17],"id":"call_00_Jxz49JNt6i4oaDnzes2I0794","name":"read","args":["","{","\"","file","_path","\"",": ","\"","data",".txt","\"","}"]}}
+{"type":"assistant/chunk","seq":49,"time":1786204701981,"data":{"turn":1,"step":1,"chunk":{"type":"block-end","index":0,"block":{"type":"reasoning","text":"The user wants me to read data.txt first, then write to replace its contents with the exact line, then reply DONE."}}}}
+{"type":"assistant/chunk","seq":50,"time":1786204701982,"data":{"turn":1,"step":1,"chunk":{"type":"block-end","index":1,"block":{"type":"tool-call","id":"call_00_Jxz49JNt6i4oaDnzes2I0794","name":"read","arguments":"{\"file_path\": \"data.txt\"}"}}}}
+{"type":"assistant/chunk","seq":51,"time":1786204701982,"data":{"turn":1,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":5803,"outputTokens":71,"cacheReadTokens":0,"reasoningTokens":26}}}}
+{"type":"assistant/chunk","seq":52,"time":1786204701982,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
+{"type":"assistant/message","seq":53,"time":1786204701988,"data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"reasoning","text":"The user wants me to read data.txt first, then write to replace its contents with the exact line, then reply DONE."},{"type":"tool-call","id":"call_00_Jxz49JNt6i4oaDnzes2I0794","name":"read","arguments":"{\"file_path\": \"data.txt\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"9060e190-9971-4838-81bf-48c3e3888609"},"usage":{"inputTokens":5803,"outputTokens":71,"cacheReadTokens":0,"reasoningTokens":26}},"sourceEventSeqs":[9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52],"surfaceOp":"append"}
+{"type":"tool/call","seq":54,"time":1786204701990,"data":{"turn":1,"step":1,"callId":"call_00_Jxz49JNt6i4oaDnzes2I0794","name":"read","arguments":"{\"file_path\": \"data.txt\"}"}}
+{"type":"tool/result","seq":55,"time":1786204702006,"data":{"turn":1,"step":1,"message":{"source":{"kind":"tool","callId":"call_00_Jxz49JNt6i4oaDnzes2I0794"},"content":[{"type":"tool-result","toolCallId":"call_00_Jxz49JNt6i4oaDnzes2I0794","content":[{"type":"text","text":"<path>{{cwd}}/data.txt</path>\n<type>file</type>\n<content>\n1: original contents\n\n(End of file - total 1 lines)\n</content>"}],"isError":false}],"role":"user","id":"1406fd7d-f181-41d0-b0db-ef196010f620"},"meta":{"path":"{{cwd}}/data.txt","offset":1,"lines":[{"number":1,"text":"original contents"}],"totalLines":1}},"sourceEventSeqs":[54],"surfaceOp":"append"}
+{"type":"step/end","seq":56,"time":1786204702006,"data":{"turn":1,"step":1}}
+{"type":"step/start","seq":57,"time":1786204702016,"data":{"turn":1,"step":2}}
+{"type":"assistant/chunk","seq":58,"time":1786204703539,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
+{"type":"tool-call-chunks","seq0":59,"time0":1786204703539,"data":{"turn":1,"step":2,"index":0,"dt":[0,1,0,0,0,1,0,0,1,0,12,2,0,0,0,22,35,1,0,0,0,0,0,1,0,8,2,0,0,71,1,0,0,1,0],"id":"call_00_ET_7mLiYX652hJA9GW6d1bl4653","name":"write","args":["","{","\"","file","_path","\"",": ","\"","data",".txt","\"",", ","\"","content","\"",": ","\"","The"," replacement"," line"," is"," deliberately"," longer"," than"," the"," configured"," sixty","-four"," byte"," diff","-b","asis"," bound",".","\"","}"]}}
+{"type":"assistant/chunk","seq":95,"time":1786204703720,"data":{"turn":1,"step":2,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"call_00_ET_7mLiYX652hJA9GW6d1bl4653","name":"write","arguments":"{\"file_path\": \"data.txt\", \"content\": \"The replacement line is deliberately longer than the configured sixty-four byte diff-basis bound.\"}"}}}}
+{"type":"assistant/chunk","seq":96,"time":1786204703720,"data":{"turn":1,"step":2,"chunk":{"type":"usage","usage":{"inputTokens":202,"outputTokens":76,"cacheReadTokens":5760,"reasoningTokens":0}}}}
+{"type":"assistant/chunk","seq":97,"time":1786204703720,"data":{"turn":1,"step":2,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
+{"type":"assistant/message","seq":98,"time":1786204703722,"data":{"turn":1,"step":2,"message":{"role":"assistant","content":[{"type":"tool-call","id":"call_00_ET_7mLiYX652hJA9GW6d1bl4653","name":"write","arguments":"{\"file_path\": \"data.txt\", \"content\": \"The replacement line is deliberately longer than the configured sixty-four byte diff-basis bound.\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"46d3792a-eded-45e7-8151-00ca0584f10b"},"usage":{"inputTokens":202,"outputTokens":76,"cacheReadTokens":5760,"reasoningTokens":0}},"sourceEventSeqs":[58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97],"surfaceOp":"append"}
+{"type":"tool/call","seq":99,"time":1786204703722,"data":{"turn":1,"step":2,"callId":"call_00_ET_7mLiYX652hJA9GW6d1bl4653","name":"write","arguments":"{\"file_path\": \"data.txt\", \"content\": \"The replacement line is deliberately longer than the configured sixty-four byte diff-basis bound.\"}"}}
+{"type":"tool/result","seq":100,"time":1786204703740,"data":{"turn":1,"step":2,"message":{"source":{"kind":"tool","callId":"call_00_ET_7mLiYX652hJA9GW6d1bl4653"},"content":[{"type":"tool-result","toolCallId":"call_00_ET_7mLiYX652hJA9GW6d1bl4653","content":[{"type":"text","text":"<path>{{cwd}}/data.txt</path>\n<type>file</type>\n<content>\nUpdated file\n</content>"}],"isError":false}],"role":"user","id":"98c41fc1-6ce6-445f-94f7-32aa7e1c6ea7"},"meta":{"diffs":[]}},"sourceEventSeqs":[99],"surfaceOp":"append"}
+{"type":"step/end","seq":101,"time":1786204703740,"data":{"turn":1,"step":2}}
+{"type":"step/start","seq":102,"time":1786204703749,"data":{"turn":1,"step":3}}
+{"type":"assistant/chunk","seq":103,"time":1786204705029,"data":{"turn":1,"step":3,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}
+{"type":"assistant/chunk","seq":104,"time":1786204705029,"data":{"turn":1,"step":3,"chunk":{"type":"text-delta","index":0,"text":"D"}}}
+{"type":"assistant/chunk","seq":105,"time":1786204705053,"data":{"turn":1,"step":3,"chunk":{"type":"text-delta","index":0,"text":"ONE"}}}
+{"type":"assistant/chunk","seq":106,"time":1786204705055,"data":{"turn":1,"step":3,"chunk":{"type":"block-end","index":0,"block":{"type":"text","text":"DONE"}}}}
+{"type":"assistant/chunk","seq":107,"time":1786204705055,"data":{"turn":1,"step":3,"chunk":{"type":"usage","usage":{"inputTokens":100,"outputTokens":3,"cacheReadTokens":6016,"reasoningTokens":0}}}}
+{"type":"assistant/chunk","seq":108,"time":1786204705056,"data":{"turn":1,"step":3,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}
+{"type":"assistant/message","seq":109,"time":1786204705057,"data":{"turn":1,"step":3,"message":{"role":"assistant","content":[{"type":"text","text":"DONE"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"ddf50859-b0b9-404d-a71c-a1f11ff53341"},"usage":{"inputTokens":100,"outputTokens":3,"cacheReadTokens":6016,"reasoningTokens":0}},"sourceEventSeqs":[103,104,105,106,107,108],"surfaceOp":"append"}
+{"type":"step/end","seq":110,"time":1786204705057,"data":{"turn":1,"step":3}}
+{"type":"turn/end","seq":111,"time":1786204705058,"data":{"turn":1,"reason":{"kind":"completed"}}}
@@ -0,0 +1,4 @@
+{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":1,"agentInfo":{"name":"deepseek-harness-acp","version":"0.0.1"},"agentCapabilities":{"promptCapabilities":{"image":false,"audio":false,"embeddedContext":false}},"authMethods":[]}}
+{"jsonrpc":"2.0","id":2,"result":{"sessionId":"{{sessionId}}"}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_message_chunk","content":{"type":"text","text":"DONE"}}}}
+{"jsonrpc":"2.0","id":3,"result":{"stopReason":"end_turn"}}
@@ -0,0 +1 @@
+original contents
@@ -565,15 +565,16 @@ export async function readForEdit(
 }

 /**
- * Best-effort overwrite diff basis. Binary, invalid UTF-8, or a file at/above the byte limit
- * returns `null` so the write still succeeds and presentation falls back to a whole-file diff.
- * The bound is enforced on the opened descriptor rather than a prior path stat, so concurrent
- * external replacement or size changes cannot make this helper buffer more than `maxBytes`.
- * @param absolutePath - the file to read (typically a target key); it must exist.
+ * Best-effort overwrite diff basis. Binary, invalid UTF-8, a file at/above the byte limit,
+ * or a file deleted/made unreadable after the caller's preflight returns `null` so the write
+ * still succeeds and presentation falls back to a whole-file diff. The bound is enforced on
+ * the opened descriptor rather than a prior path stat, so concurrent external replacement or
+ * size changes cannot make this helper buffer more than `maxBytes`.
+ * @param absolutePath - the file to read (typically a target key).
 * @param maxBytes - exclusive upper bound for bytes held as the contextual-diff basis.
- * @param signal - aborts the read (`FS_ABORTED`).
+ * @param signal - aborts the read (`FS_ABORTED`); cancellation propagates, unlike I/O failure.
 * @returns the LF-normalized text, or null for a non-regular, at/above-limit, binary, non-UTF-8,
- * or descriptor-size-changed file.
+ * descriptor-size-changed, or unreadable file.
 */
 export async function readTextForDiff(
  absolutePath: string,
@@ -581,41 +582,50 @@ export async function readTextForDiff(
  signal?: AbortSignal,
 ): Promise<string | null> {
  throwIfAborted(signal, 'read')
-  const handle = await open(absolutePath, 'r')
-  let buffer: Buffer
-  let total = 0
-  let openedSize = 0
  try {
-    throwIfAborted(signal, 'read')
-    const info = await handle.stat()
-    throwIfAborted(signal, 'read')
-    /* v8 ignore next -- requires a post-preflight replacement with a non-file;
-     * direct coverage is not portable to Windows. */
-    if (!info.isFile()) return null
-    if (info.size >= maxBytes) return null
-    openedSize = info.size
-    // One extra byte detects growth after stat without retaining per-read backing buffers.
-    buffer = Buffer.allocUnsafe(openedSize + 1)
-    while (total < buffer.length) {
+    const handle = await open(absolutePath, 'r')
+    let buffer: Buffer
+    let total = 0
+    let openedSize = 0
+    try {
      throwIfAborted(signal, 'read')
-      const length = Math.min(buffer.length - total, DIFF_BASIS_READ_CHUNK_BYTES)
-      const { bytesRead } = await handle.read(buffer, total, length, null)
-      if (bytesRead === 0) break
-      total += bytesRead
+      const info = await handle.stat()
+      throwIfAborted(signal, 'read')
+      if (!info.isFile()) return null
+      if (info.size >= maxBytes) return null
+      openedSize = info.size
+      // One extra byte detects growth after stat without retaining per-read backing buffers.
+      buffer = Buffer.allocUnsafe(openedSize + 1)
+      while (total < buffer.length) {
+        throwIfAborted(signal, 'read')
+        const length = Math.min(buffer.length - total, DIFF_BASIS_READ_CHUNK_BYTES)
+        const { bytesRead } = await handle.read(buffer, total, length, null)
+        if (bytesRead === 0) break
+        total += bytesRead
+      }
+    } finally {
+      await handle.close()
+    }
+    throwIfAborted(signal, 'read')
+    if (total !== openedSize) return null
+    const basis = buffer.subarray(0, total)
+    if (basis.includes(0)) return null
+    try {
+      return normalizeLineEndings(new TextDecoder('utf-8', { fatal: true }).decode(basis))
+    } catch (error: unknown) {
+      /* v8 ignore next 2 -- TextDecoder({fatal}) only throws TypeError on invalid bytes;
+       * any other throw is an unreachable runtime fault. */
+      if (!(error instanceof TypeError)) throw error
+      return null
    }
-  } finally {
-    await handle.close()
-  }
-  throwIfAborted(signal, 'read')
-  if (total !== openedSize) return null
-  const basis = buffer.subarray(0, total)
-  if (basis.includes(0)) return null
-  try {
-    return normalizeLineEndings(new TextDecoder('utf-8', { fatal: true }).decode(basis))
  } catch (error: unknown) {
-    /* v8 ignore next 2 -- TextDecoder({fatal}) only throws TypeError on invalid bytes; any other throw is an unreachable runtime fault. */
-    if (!(error instanceof TypeError)) throw error
-    return null
+    // Cancellation is the caller's intent and still propagates.
+    if (error instanceof FsError) throw error
+    // A descriptor-phase errno — deleted or made unreadable after the caller's
+    // preflight, or a faulted read — costs only the optional basis: a committed
+    // write must not fail for a presentation-only pre-read.
+    if (error instanceof Error && 'code' in error) return null
+    throw error
  }
 }

@@ -398,6 +398,64 @@ describe('readTextForDiff', () => {
    }
  })

+  it('returns null when the file vanishes before the basis open (deletion race)', async () => {
+    expect(await readTextForDiff(join(dir, 'deleted-after-preflight.txt'), 32)).toBeNull()
+  })
+
+  it('returns null when the opened descriptor is no longer a regular file', async () => {
+    const file = join(dir, 'swapped.txt')
+    await writeFile(file, 'abcdef')
+    vi.resetModules()
+    vi.doMock('node:fs/promises', async (importOriginal) => {
+      const actual = await importOriginal<typeof import('node:fs/promises')>()
+      return {
+        ...actual,
+        async open(...args: Parameters<typeof actual.open>) {
+          const handle = await actual.open(...args)
+          return {
+            close: handle.close.bind(handle),
+            read: handle.read.bind(handle),
+            async stat(...statArgs: Parameters<typeof handle.stat>) {
+              const info = await handle.stat(...statArgs)
+              return Object.assign(info, { isFile: () => false })
+            },
+          }
+        },
+      }
+    })
+
+    try {
+      const { readTextForDiff: isolatedReadTextForDiff } = await import('../src/fsio.ts')
+      expect(await isolatedReadTextForDiff(file, 32)).toBeNull()
+    } finally {
+      vi.doUnmock('node:fs/promises')
+      vi.resetModules()
+    }
+  })
+
+  it('propagates a non-errno fault instead of masking it as a null basis', async () => {
+    const file = join(dir, 'faulted.txt')
+    await writeFile(file, 'abcdef')
+    vi.resetModules()
+    vi.doMock('node:fs/promises', async (importOriginal) => {
+      const actual = await importOriginal<typeof import('node:fs/promises')>()
+      return {
+        ...actual,
+        async open() {
+          throw new TypeError('forged programming fault')
+        },
+      }
+    })
+
+    try {
+      const { readTextForDiff: isolatedReadTextForDiff } = await import('../src/fsio.ts')
+      await expect(isolatedReadTextForDiff(file, 32)).rejects.toThrow('forged programming fault')
+    } finally {
+      vi.doUnmock('node:fs/promises')
+      vi.resetModules()
+    }
+  })
+
  it('returns null for binary and invalid UTF-8 without blocking the caller write', async () => {
    await writeFile(join(dir, 'bin'), Buffer.from([0x68, 0x00, 0x69]))
    await writeFile(join(dir, 'bad'), Buffer.from([0x68, 0xff, 0x69]))
@@ -24,7 +24,7 @@ import type {
  StreamChunk,
  TokenUsage,
 } from '@deepseek-ai/dsh-llm'
-import { LlmAdapter, LlmError, assertNever, resolveRetryPolicy } from '@deepseek-ai/dsh-llm'
+import { LlmAdapter, LlmError, ReasoningEffortId, assertNever, resolveRetryPolicy } from '@deepseek-ai/dsh-llm'

 /**
 * One recorded model call. `throw` may replay prefix chunks before failing;
@@ -51,6 +51,18 @@ export interface ReplayModelConfig {
  description?: string
  /** Optional positive integer context capacity published by the replay adapter. */
  contextWindow?: number
+  /**
+   * Optional per-request output cap the replay route materializes when callers
+   * omit one, so replay reconstructs the request header a live catalog produced.
+   */
+  defaultMaxTokens?: number
+  /** Optional reasoning-effort ids the replay route accepts, in display order. */
+  reasoningEfforts?: string[]
+  /**
+   * Optional effort materialized when callers omit one; must appear in
+   * {@link reasoningEfforts} or call resolution rejects the route.
+   */
+  defaultReasoningEffort?: string
 }

 /** One provider route exposed by the replay adapter. */
@@ -585,6 +597,19 @@ class ReplayAdapter extends LlmAdapter {
      ...configuredModel?.contextWindow === undefined
        ? {}
        : { context: { contextWindow: configuredModel.contextWindow } },
+      ...configuredModel?.defaultMaxTokens === undefined
+        ? {}
+        : { defaultMaxTokens: configuredModel.defaultMaxTokens },
+      ...configuredModel?.reasoningEfforts === undefined
+        ? {}
+        : {
+          reasoning: {
+            efforts: configuredModel.reasoningEfforts.map(id => ({ id: ReasoningEffortId(id), name: id })),
+            ...configuredModel.defaultReasoningEffort === undefined
+              ? {}
+              : { defaultEffort: ReasoningEffortId(configuredModel.defaultReasoningEffort) },
+          },
+        },
    })
  }