verifier 0.22: typed base_unresolved and manifest_removed stops; align preview base detection and trigger reports-dir exclusion #1071

Deferred by the engineering-review implementation loop from #1070 (issue #1023).

Problem

Verifier 0.21 shipped in 1.2.0 with closed enums, so #1070 could not add typed values for the two new fail-closed stops it introduced. They are published as:

• "no base resolved": base_status: ref_missing, refs_missing, fetch_base, with detail beginning with the token base_unresolved;
• "manifest removed": a human stop with exit 2.

A consumer can tell the no-base stop from the existing head-missing stop only by that free-text detail prefix (PR #1070 review, C1-2). The next verifier schema version should carry typed values so consumers do not parse detail.

Smaller leftovers from the same PR, for the same owner:

• verify --preview still uses remote-only base detection (src/agents_shipgate/cli/verify/orchestrator.py near the preview route), unlike the main route after fix(verify): fail closed without a base or with a deleted manifest #1070.
• trigger --git-diff still counts the reports directory (src/agents_shipgate/cli/trigger.py:138) that check now excludes when it holds only uncommitted Shipgate artifacts.
• Other archive ConfigErrors (partial clone with missing objects; cli/verify/git.py around the archive helpers) can still reach the manifest diagnoser in agent mode and be routed to "edit shipgate.yaml".
• --head <sha> that deletes shipgate.yaml while the checkout still has it overlays the worktree manifest (pre-existing; verdict insufficient_evidence, not mergeable).

Proposed fix

In verifier 0.22 (a minor-cycle schema change with the usual STABILITY migration note and regenerated docs/ schema): add base_status: base_unresolved and a manifest_removed reason, keep the detail prefix for one cycle, and update the Action outputs and the agent-mode next_action to read the typed value. Fold the four smaller leftovers in or split them as the implementer sees fit.

Acceptance criteria

• Verifier 0.22 publishes typed values for both stops; consumers no longer parse detail.
• verify --preview resolves the base the same way the main route does.
• trigger --git-diff and check agree on excluding the reports directory.

Source

Engineering review 2026-10-12 follow-up (PR #1070 review cycle 1 and implementer notes). Tracked in #1060.