feat(trekplan): Regression and On failure step rules, and trial 2's minor fixes

The minor points (B8-B12, C13, C14, C16, C17) of the second voyage-lekerepo
trial (2026-10-08), each verified against the code and started with a test
that failed first.

- K10: optional step field `Regression:` - one command the criteria runner
  allows, unpiped; plan-validator refuses one that can never run
  (PLAN_STEP_REGRESSION_NOT_RUNNABLE). Any plan_version, no bump.
- K11: `On failure:` opens with revert | retry | skip | escalate, or the
  validator warns (PLAN_STEP_ON_FAILURE_UNKNOWN); onFailureAction in
  plan-schema.
- B8 (operator decision 2026-10-08): minors open after the last critic round
  are listed numbered in the Phase 10 summary; the ones the operator picks are
  fixed and get one more round (--extra-round when the 3 are spent).
- B11: plan-review dedup merges two reviewers' findings on the same file:line
  with the same content (trial pair: Jaccard 0.44, overlap 0.83); the Jaccard
  threshold for every other pair is unchanged.
- B12: /trekbrief Step 4c says the reviewer runs in the background and is
  waited for, not "foreground, blocking".
- C13: the Phase 4 size count includes .mjs, .cjs, .mts, .cts.
- C14: --evidence shows the first output line on PASS rows.
- C16: findings-schema checks path:line citations in finding prose (error) and
  in the prose around the block (warning) against the file.
- C17: git-historian gets the brief, never proposes changing a frozen file,
  and names the remote from `git remote -v`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/HANDOVER-CONTRACTS.md

@@ -266,6 +266,9 @@ prose form (relaxed in S26 so the template's prose emission parses).
    - the optional step fields `Interface in:`, `Interface out:`, `Review focus:` are never empty when present (consumers tolerate their absence);
    - `ceremony` is one of the three classes; an `architectural` plan has `## Design` with the subsections Architecture, Data Flow, Interfaces, Data Models, Error Handling, Module Map, Architecture Rules, Requirements Check, plus `## Test Strategy`; the module map (mermaid) has no cycle; every architecture rule says "checked by `<command>`" (with a Proof column naming an existing step) or "advisory — `.claude/rules/<file>.md`".
 6. **`## Critic Verdict`** (written by `lib/validators/plan-gate.mjs --record`, never by hand): one fenced `json` block, schema `voyage.plan-verdict/1` — `round`, `max_rounds` (3), `extra_rounds`, `plan_sha256`, `verdict` (`BLOCK` | `REVISE` | `PASS`), `counts`, `findings` (deduplicated, each with `severity`). `plan_sha256` hashes the plan minus its review log (the `> **Plan quality:` line and the sections Critic Verdict, Revisions, Plan Quality Score, Adversarial Pass 2), with CRLF and line-end whitespace normalized. The verdict sits inside the plan because Claude Code's plan approval hands a hook the plan file's text and nothing beside it.
+7. **Every plan_version, no version bump** (a plan without the field validates unchanged; voyage-lekerepo trial 2, 2026-10-08):
+   - **K10 — `Regression:`** (optional step field): ONE backticked command the criteria runner's allowlist runs, with no pipe and no `&&` (first backticked span, as for `Verify:`). The executor runs it green before the step's checkpoint; a step without it runs nothing new. `Verify:` stays the step's own red-first test. One that can never run is `PLAN_STEP_REGRESSION_NOT_RUNNABLE` (an error; a warning under `--soft`).
+   - **K11 — `On failure:`** opens with one of `revert`, `retry`, `skip`, `escalate` (case-insensitive; a leading `**`, `_`, backtick or `-` is ignored, other leading characters are not; `onFailureAction` in `lib/parsers/plan-schema.mjs`), the words `/trekexecute` reads; any other opening is the warning `PLAN_STEP_ON_FAILURE_UNKNOWN`. A missing `On failure:` is unchanged (the executor defaults to `escalate`).
 
 **Validation strategy:**
 
@@ -295,6 +298,8 @@ The strongest validation in the entire pipeline. Phase 5.5 (planning-orchestrato
 | `PLAN_MODULE_MAP_EMPTY` / `PLAN_MODULE_CYCLE` | 1.8 architectural: no mermaid module map, or a cycle in it (all `mermaid` blocks of `### Module Map` form one map) | Draw it; break the cycle |
 | `PLAN_MODULE_MAP_UNPARSED` | 1.8 architectural: a module-map line that looks like a link but gives no edge | Write it as `a --> b` |
 | `PLAN_ARCH_RULE_NO_ENFORCER` / `PLAN_ARCH_RULE_NO_PROOF` | 1.8 architectural: a rule without an enforcer, or a checked rule without an existing proving step | Name the enforcer; name the step |
+| `PLAN_STEP_REGRESSION_NOT_RUNNABLE` | K10, any version: a step's `Regression:` is not one command the allowlist runs (a pipe, `&&`, no backticks, an unknown runner) | One backticked runner call (`npm test`); a wider check goes in `bash tests/<script>.sh` |
+| `PLAN_STEP_ON_FAILURE_UNKNOWN` | K11, any version, warning: `On failure:` does not open with revert / retry / skip / escalate | Open with the word, then the specifics |
 
 **The plan gate (K3).** `node lib/validators/plan-gate.mjs <plan.md> [--json]` decides whether a plan may go on: **0** = it validates strict, its `## Critic Verdict` matches the current text, no BLOCKER is open, and every open MAJOR was accepted by the operator; **1** = stop, with `reasons` (`PLAN_GATE_INVALID_PLAN`, `PLAN_GATE_VERSION` — below plan_version 1.8, `PLAN_GATE_NO_VERDICT`, `PLAN_GATE_VERDICT_MALFORMED`, `PLAN_GATE_VERDICT_STALE`, `PLAN_GATE_OPEN_BLOCKER`, `PLAN_GATE_ROUNDS_EXHAUSTED`, `PLAN_GATE_OPEN_MAJOR` — rounds left: revise, `PLAN_GATE_OPEN_MAJOR_FINAL` — after the last round: ask the operator) and `warnings` (`PLAN_GATE_OPEN_MAJOR` for majors the operator accepted); **2** = could not read the plan. `--hash <plan.md>` prints the operative hash; Phase 9 takes it before the reviewers read the plan. `--record <plan.md> --reviewed <hash>` reads plan-review-dedup output on stdin (which lists the reviewers that delivered, `sources`) and writes the next round; exit 2 when a reviewer is missing or the plan changed since `--hash`; it refuses round 4 (exit 1, stop and ask) unless `--extra-round` follows the operator's yes, and refuses that flag before the cap is spent. Unrated findings count as blockers. The review log is excluded from the hash only up to its first other heading, so a step placed under it is hashed. `--accept-open <plan.md>` records the operator's "build as is" for the current round's open MAJORs (`accepted_open` in the verdict block, bound to the round and the plan hash; only after the last round; never for a BLOCKER; exit 1 when rounds are left, the verdict is stale, a blocker is open or no major is). Operator decision 2026-10-08: open majors used to be warnings, and a weakness the critics named was built and came back from `/trekreview` as MAJOR. plan-critic and scope-guardian rate on the review catalogue's tiers. The verdict is a trace of the review, not a signature.