Is this a reproducible bug?

• I confirm this is a reproducible bug, not a feature request, idea, question, contribution proposal, or direction check.

Current behavior

On restart, herdr fails to resume claude panes with No conversation found with session ID: <uuid>. herdr-agent-state.sh (integration v5) reports
pane.report_agent_session keyed only by the HERDR_PANE_ID env var, storing just
the id. Any process inheriting that env can claim the pane — including a nested
claude run in a different cwd. The official remember plugin triggers it: it runs
claude -p with cwd=$TMPDIR and inherited env, so its SessionStart hook reports
the throwaway session id (written under ~/.claude/projects/-tmp/) and overwrites
the pane's real id. On restore, claude --resume <id> is cwd-scoped (searches only
~/.claude/projects/<encoded-pane-cwd>/), so the -tmp session is never found.

Expected behavior

A nested/sandboxed claude run must not overwrite a pane's interactive session, and aka stored session must resume (or degrade to a clean start) instead of erroring.

Proposed fix

1. Resume by the session's real path, not the pane cwd. The hook already has
   transcript_path; the CLI already accepts report-agent --agent-session-path.
   Persist it and cd there (or resume by path) on restore — fixes it even for -tmp.
2. Authority by PID/foreground, not just HERDR_PANE_ID — only accept reports
   from the pane's tracked foreground process, so a sibling nested run can't clobber it.
3. Graceful fallback — if the stored session file is missing on restore, start
   clean instead of erroring.

Reproduction

1. In a herdr claude pane, start interactive claude in a repo, send a message.
2. From inside that pane, run a nested headless claude in another cwd:

   ( cd /tmp && env CLAUDECODE= claude -p hi --max-turns 1 )
   (or just let the remember plugin run its consolidation)

3. herdr pane get <pane_id> → agent_session.value now points to a session that
   find ~/.claude/projects -name '.jsonl' resolves under projects/-tmp/.
4. Restart herdr → pane fails with No conversation found with session ID.

Impact

Loss of claude session continuity on restart — the headline feature. Silent: the
clobber happens in the background, user only sees it after a restart. Affects every
pane whenever a nested/headless claude runs (the bundled remember plugin alone is
enough). codex unaffected (its resume is global, not cwd-scoped).

Environment

herdr 0.6.8, claude integration v5, Linux/WSL2, Claude Code (recent).