fix: prevent agent from overwriting notepad files in .sisyphus/notepads/

[javimarttinn]

Summary

• Blocks the Write tool on .sisyphus/notepads/*.md paths to prevent irreversible overwrites of append-only decision logs.
• Strengthens the Edit error recovery reminder with explicit CRITICAL RULES for notepad files.

Changes

• src/hooks/write-existing-file-guard/tool-execute-before-handler.ts
  • Added isNotepadPath check that throws a descriptive error before the existing isSisyphusPath guard allows the write.
  • Prevents agents from falling back to Write when Edit fails on notepad files.
• src/hooks/edit-error-recovery/hook.ts
  • Added a CRITICAL RULES for notepad files block to the recovery reminder.
  • Explicitly instructs the agent to use Edit with append mode and to ask the user before any destructive action on .sisyphus/notepads/.

Testing

Verified that attempting to Write a file under .sisyphus/notepads/ now raises:
Error: Notepad files (.sisyphus/notepads/*) are APPEND-ONLY. Use the Edit tool with append mode instead of Write.

Related Issues

Closes #2149

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Summary by cubic

Prevents overwriting append‑only notepad files under .sisyphus/notepads/ by blocking the Write tool and updating Edit recovery rules. Closes #2149 by enforcing append-only behavior for decision logs.

• Bug Fixes
  • Block Write for .sisyphus/notepads/* and throw a clear error: “Notepad files are APPEND‑ONLY. Use Edit to append. Never use Write.”
  • Add CRITICAL RULES to Edit error recovery: never use Write on notepads, always append with Edit, and if Edit fails again, stop and ask the user.

^{Written for commit f2bb07a. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

1 issue found across 2 files

Confidence score: 2/5

• There is a high-confidence, user-impacting bug in src/hooks/write-existing-file-guard/tool-execute-before-handler.ts: the append-only guard can be bypassed on Windows due to POSIX-only substring matching against normalized paths.
• I’m scoring this as high risk because the issue affects a protection check directly, and the severity/confidence (7/10, 8/10) suggests a likely regression in real Windows environments.
• Pay close attention to src/hooks/write-existing-file-guard/tool-execute-before-handler.ts - path handling needs platform-aware matching so the guard cannot be skipped on Windows.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/hooks/write-existing-file-guard/tool-execute-before-handler.ts">

<violation number="1" location="src/hooks/write-existing-file-guard/tool-execute-before-handler.ts:141">
P1: Notepad append-only guard is bypassable on Windows because path detection uses a POSIX-only substring against platform-normalized paths.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P1: Notepad append-only guard is bypassable on Windows because path detection uses a POSIX-only substring against platform-normalized paths.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At src/hooks/write-existing-file-guard/tool-execute-before-handler.ts, line 141:

<comment>Notepad append-only guard is bypassable on Windows because path detection uses a POSIX-only substring against platform-normalized paths.</comment>

<file context>
@@ -138,6 +138,18 @@ export async function handleWriteExistingFileGuardToolExecuteBefore(params: {
   }
 
   const isSisyphusPath = canonicalPath.includes("/.sisyphus/")
+  const isNotepadPath = canonicalPath.includes("/.sisyphus/notepads/")
+  if (isNotepadPath) {
+    log("[write-existing-file-guard] Blocking notepad overwrite", {
</file context>

Suggested change

	const isNotepadPath = canonicalPath.includes("/.sisyphus/notepads/")
	const isNotepadPath = canonicalPath.replace(/\\/g, "/").includes("/.sisyphus/notepads/")