feat(boss): bolder autonomous /boss — grounding-PASS auto-sign, rollback sandbox, reference issue

Retire the obligatory five-lens spec-skeptic auto-sign panel (worst case
18 agent runs per spec under /boss). The autonomous signature is now the
Step-5 grounding-check PASS alone — an independent fresh-context agent's
verdict against currently-green tests; a no-override BLOCK/INFRA_ERROR
routes to the human sign-off pause.

The judgement the panel applied moves upstream into specify Step 1.5,
whose stance inverts: a load-bearing fork the orchestrator can DERIVE an
answer for (sources, code, consistency, risk) is decided boldly and
recorded on the run's reference issue; only a pure-preference fork
bounces. spec-skeptic survives as an optional ad-hoc bias-breaker the
orchestrator pulls when unsure whether its leaning is judgement or bias —
not a gate, not a veto.

Every /boss run carries a mandatory reference issue (created if the cycle
had none): the fork-decision log, the orchestrator's cross-run memory,
and the only surviving trace of a hard-dropped attempt.

Relax main-sacrosanct below the session anchor: within an autonomous run
the orchestrator may git reset --hard its OWN UNPUSHED commits above the
anchor on a dead end — never below the anchor, never a pushed commit
(forward-only/revert). Discarded attempts are hard-dropped, no parking.

Verified across the 9 edited files by a 4-lens adversarial review
(retired-panel residue, cross-file contracts, rollback-boundary safety,
stance coherence): unanimous SOUND. Baseline tagged pre-autosign-rework.

closes #8

docs/conventions.md

@@ -97,10 +97,18 @@ too.
 - **Only the orchestrator commits.** No skill agent runs `git commit`.
   Agents write into the working tree as unstaged changes; the
   orchestrator inspects, decides commit shape, and commits.
-- **main HEAD is sacrosanct.** Nobody runs `git reset` / `git revert`
-  on main (or any other protected branch). main moves forward only via
-  orchestrator commits; a wrong agent diff is discarded with
-  `git checkout -- <paths>` / `git stash`, never by rewinding main.
+- **main HEAD is sacrosanct — below the session anchor.** Nobody runs
+  `git reset` / `git revert` on user-ratified main history (or any
+  protected branch). main moves forward only via orchestrator commits; a
+  wrong agent diff is discarded with `git checkout -- <paths>` /
+  `git stash`, never by rewinding ratified history.
+  **One narrow `/boss` exception — the rollback sandbox:** inside an
+  autonomous run the orchestrator anchors on the `main` HEAD it started
+  from (the last user-ratified state) and MAY `git reset --hard` its
+  *own* commits *above* that anchor — autonomous, **unpushed** work only
+  — back toward (never below) the anchor when it has run into a dead end.
+  A pushed commit has left the sandbox and is forward-only (`git revert`).
+  See `../boss/SKILL.md` § Direction freedom.
 
 These also appear in the universal-discipline fragment
 (`../templates/CLAUDE.md.fragment`) that each project's CLAUDE.md
@@ -111,8 +119,9 @@ imports.
 The tracker is **Gitea** and the commit close-marker is `closes #N`
 (`refs #N` for non-closing work). The per-project repo slug and the
 list/show commands live in the project's CLAUDE.md project facts
-(see below) — the `boss` skill reads the forward queue from there,
-and the `spec-skeptic` `scope-fork` juror reads single issues with
+(see below) — the `boss` skill reads the forward queue from there and
+records its fork decisions on the run's reference issue there, and an
+ad-hoc `spec-skeptic` `scope-fork` dispatch reads single issues with
 their comment threads from there.
 
 ## Pipeline