fix: annotate-last resolves wrong session after cd

[janah01]

Problem

/plannotator-last annotates the wrong message when the user cd's during a Claude Code session. No error, no warning — just the wrong content in the annotation UI.

What happens

findSessionLogsForCwd() builds a project slug from process.cwd(). Claude Code's session log lives under the slug for the original session directory, not the current shell CWD.

1. Session starts in /Users/me → log stored at ~/.claude/projects/-Users-me/<id>.jsonl
2. User runs cd ~/projects/my-app
3. /plannotator-last uses CWD → looks in ~/.claude/projects/-Users-me-projects-my-app/
4. Finds a stale session from a previous day that happened to use that directory
5. Opens the annotation UI with that old session's last message

The user has no way to tell something went wrong until they read the text and realize it's not what they expected. By then they may have already written annotations against the wrong content.

Who this affects

Anyone who cd's during a session. That's a common workflow — cd into a repo, run commands, then annotate the assistant's response.

This is a Claude Code-only bug. Codex uses CODEX_THREAD_ID, OpenCode and Pi use their SDK APIs — none of them resolve sessions via CWD. The fix is scoped to the Claude Code else branch; no other harness is touched.

Fix

Three-tier session resolution (most precise first):

1. PPID session metadata (new, primary path)

Claude Code writes ~/.claude/sessions/<pid>.json:

{"pid": 17326, "sessionId": "112c3961-...", "cwd": "/Users/me", "startedAt": ...}

When /plannotator-last runs, its parent process is the Claude Code instance. process.ppid → read the metadata → get the exact session ID and original CWD → open the exact JSONL. O(1), no scanning, no mtime heuristics.

2. CWD slug match (existing behavior, unchanged)

Works when the shell CWD hasn't diverged from the session's project directory.

3. Ancestor walk (new fallback)

Walk up the directory tree trying parent slugs. Handles the case where PPID metadata is unavailable and the user cd'd deeper into a subdirectory.

Other changes

• getLastRenderedMessage() now catches read errors instead of throwing on missing/corrupt files, so the fallback cascade doesn't crash mid-resolution.
• Extracted tryLogCandidates() to deduplicate the candidate iteration loop (was copy-pasted between CWD and ancestor fallbacks).

Test plan

• 44 tests pass (bun test apps/hook/server/)
• 3 new tests for findSessionLogsByAncestorWalk (root returns empty, walks up to parent, skips exact CWD)
• This is a Claude Code-only bug. Codex uses CODEX_THREAD_ID, OpenCode and Pi use their SDK APIs — none of them resolve sessions via CWD. The fix is scoped to the Claude Code else branch; no other harness is touched.

[backnotprop]

nice work

[backnotprop]

making one adjustment for windows