FROM feat/739-slack-compact TO development

[ryaneggz]

Closes #739

Final design after adversarial review

• Exact-pins ryaneggz/pi-messenger-bridge PR feat(slack): Manage PI Agent from Slack #2 at 4056384d7e3901809019e006185a68987fcc8c0b, carrying the complete thread/admin/compact stack in a master-targeted PR.
• The package owns authenticated compact parsing, preserves raw Slack text, acknowledges the exact originating chat/thread, compacts with the current generation/context, confirms Slack disconnect, then signals restart.
• Ordinary inbound messages use unpredictable internal request IDs activated only at the matching user message_start; markers are stripped before provider/session context. Explicit active-turn source tracking prevents local TUI steer/follow-up turns from posting to Slack.
• The supervisor pins cwd/session storage, resumes with --continue, launches Pi in an isolated process group, and performs bounded exact-group TERM→KILL cleanup even when the leader has exited.
• Restart IPC is a mode-0600 Unix socket whose server authenticates the exact supervised Pi PID with Linux SO_PEERCRED. Child tools, pane output, /proc fd tricks, and sibling processes cannot forge it.
• The harness installs and lifecycle-smokes the exact bridge artifact in CI; Codex recovery, thread replies, admin commands, Hermes isolation, heartbeat/status, and lock cleanup remain covered.

Verification

• Bridge head 4056384d: 122 tests; Biome lint; TypeScript typecheck; build.
• Harness head 2ab05695: 39 files / 491 tests, including real Pi continuation, IPC forgery rejection, process-group lifecycle, local-turn isolation, cross-chat/thread ordering, and exact installed-artifact smoke.
• Shell: Bash syntax and ShellCheck warning gate pass.
• Eval: 98 probes; 94 PASS / 4 SKIPPED / 0 REGRESSION.
• Exact-pin consumer CI: https://github.com/mifunedev/openharness/actions/runs/31485327740
• Independent final review: PASS, no high/medium findings.
• Deterministic audit: PR-AUDIT-PROMOTABLE.

Dependency PR

• FROM feat/739-compact-control TO master ryaneggz/pi-messenger-bridge#2
• The fork has GitHub Issues disabled; harness issue feat(#739): compact Pi gateway session from Slack #739 is the tracking issue.

Neither PR is merged by automation.

[ryaneggz]

Merge-order hazard with #748 — invisible at this PR's gate

git merge-tree --write-tree --messages \
  upstream/feat/739-slack-compact upstream/feat/746-firstmate-executor

CONFLICT (content): Merge conflict in .oh/evals/RESULTS.md
CONFLICT (content): Merge conflict in CHANGELOG.md

This PR and #748 both read MERGEABLE / CLEAN, because GitHub compares each
branch only against development and never against the other. The conflict is
real.

Whichever of the two merges second must re-run /eval and regenerate
.oh/evals/RESULTS.md on top of the merged base. Hand-resolving that file
produces a benchmark that describes neither branch. CHANGELOG.md is an ordinary
textual resolve.

Structural, not a one-off: every branch that runs /eval rewrites the whole
RESULTS.md, so any two such branches conflict by construction. Worth its own
issue; not filed.