feat(intent): /trekplan halts without an approved intent; the approval is stamped on both paths

Veikart steg 1, økt 1 av 2. The three holes measured in the grounds:
(1) ## Intent / ## Goal were only checked for existence, (2) no approval
marker existed, (3) brief-approved was emitted only on the auto path.

- lib/validators/intent-approval.mjs: --check / --stamp. The marker is
  intent_approved_hash (sha256 over normalized ## Intent + ## Goal) +
  intent_approved_at. Editing either section after approval → STALE.
- /trekplan Phase 1 (Read the brief, both --brief and --project): runs
  --check and HALTS on BRIEF_INTENT_NOT_APPROVED / _STALE / _INVALID with
  the remedy spelled out; an unrunnable check halts too.
- /trekbrief Phase 4h (before the Phase 5 fork, asked even in --quick):
  shows Intent + Goal verbatim, AskUserQuestion Approve / Revise / Leave;
  only "Approve" runs --stamp. --stamp emits brief-approved, so the manual
  (default) path records it; the auto path's own emission is removed.
  New mode /trekbrief --approve <project-dir> = Phase 4h alone.
- README, CLAUDE.md, command-modes, HANDOVER-CONTRACTS §Handover 1,
  jsonl-schemas (trekbrief-stats gains intent_approved).

Valgt ingen brief_version-bump fordi skjemaendringen er rent additiv (to
valgfrie felt) og kravet sitter i /trekplan — enhver produsents brief kan
godkjennes via /trekbrief --approve uten produsentendring. Valgt eget
--check-kall i stedet for et flagg på brief-validator fordi --brief-stien
i dag ikke kjører validatoren i det hele tatt; et nytt validatorkall der
ville også stoppe på andre feil. Valgt fallback-datamappe = målestokkens
(plugins/data/voyage-…) fordi CLAUDE_PLUGIN_DATA er tom i Bash-miljøet og
event-emits egen fallback er stille skip — slik ble brief-approved 0 records.

What the marker does NOT prove (module header, command prose, contract):
same user, same machine — any session can stamp. A trace, not a signature.

Suite 1183 → 1201 (1199/0/2). Mutants M1–M5 (stale check off, check
always valid, gate line removed, stamp emits nothing, no normalization)
each fell ≥ 1 test. yardstick unchanged: RED, 1 of 3 countable.

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

docs/HANDOVER-CONTRACTS.md

@@ -74,6 +74,8 @@ Every validator exposes a CLI: `node lib/validators/<name>.mjs --json <path>` re
 | `phase_signals` | list | optional (v5.1+) | list of `{phase, effort?, model?}` entries | Per-phase effort + model commitment from Phase 3.5. Mutually exclusive with `phase_signals_partial`. |
 | `phase_signals_partial` | bool | optional (v5.1+) | `true` | Force-stop record from Phase 3.5. Mutually exclusive with `phase_signals`. |
 | `framing` | string | **required at ≥ 2.2** (v5.5) | `preserve \| refine \| replace \| new-direction` | How this brief relates to prior operator intent. Enum-checked on any version when present; missing → `BRIEF_MISSING_FRAMING` at `brief_version ≥ 2.2`. Layer 1 of the framing-alignment defense. |
+| `intent_approved_hash` | string | optional in the schema; **required by `/trekplan`** (veikart steg 1) | `"sha256:<64 hex>"` | Hash over the normalized `## Intent` + `## Goal`. Written only by `lib/validators/intent-approval.mjs --stamp`, which `/trekbrief` runs on the operator's explicit "Approve" (Phase 4h, or `--approve <project-dir>`). |
+| `intent_approved_at` | string | optional | ISO-8601 | When the stamp was written. Informational; the gate reads the hash. |
 
 **Body invariants:** required sections (validator runs in strict mode at write-time, soft mode at read-time):
 - `## TL;DR` — **required at `brief_version ≥ 2.2`** (v5.5); ≤ 5 content lines (soft cap → `BRIEF_TLDR_TOO_LONG` warning). Layer 3 of the framing-alignment defense.
@@ -104,7 +106,10 @@ Optional but standard sections: `## Non-Goals`, `## Constraints`, `## Preference
 
 **Pre-2.2 briefs receive zero framing enforcement (producer-elective defense).** The framing-alignment defense is gated at `brief_version ≥ 2.2`, so a brief declaring `2.0` or `2.1` gets **none** of it: `framing` is optional and a missing value is not an error, the `## TL;DR` section is not required, and the `brief-reviewer` memory-alignment dimension scores N/A. The backward-compatibility this buys is deliberate, but it also means the framing defense is **producer-elective**: any producer can sidestep the entire defense — deliberately or by shipping a legacy template — simply by declaring `brief_version: "2.1"`, and the pipeline raises no signal by default. This is a documented property of the contract, not a bug. Two remedies close it for a given consumer: (1) require upstream producers to emit `brief_version: "2.2"` (which forces `framing` + `## TL;DR`); or (2) pass the opt-in **`--min-brief-version <ver>`** flag to `/trekplan` or `/trekresearch` (forwarded to the validator as `--min-version`), which raises a `BRIEF_VERSION_BELOW_MINIMUM` **warning** — never a block — when a brief declares a version below the floor. The flag defaults to off, so the N-1 compatibility window for `2.0`/`2.1` briefs is preserved unless a consumer explicitly opts into the stricter floor.
 
+**Intent approval gate (veikart steg 1) — additive schema, consumer-side requirement.** The two `intent_approved_*` fields are additive and optional in the schema: `brief-validator.mjs` does not require them, `/trekresearch` does not read them, and no `brief_version` bump is involved. The requirement lives in `/trekplan` Phase 1 (`### Read the brief`), which runs `intent-approval.mjs --check` and **halts** on `BRIEF_INTENT_NOT_APPROVED` (no marker), `BRIEF_INTENT_APPROVAL_STALE` (`## Intent` or `## Goal` changed after approval) or `BRIEF_INTENT_APPROVAL_INVALID` (malformed marker, or a section missing). It is version-independent, so a brief from ANY producer, of any `brief_version`, stops at `/trekplan` until approved. No producer has to emit anything new: the operator approves through `/trekbrief --approve <project-dir>`, a Voyage-side step open to every producer's brief, so no producer is privileged. `trekreview` briefs are exempt. **What the marker does not prove:** same user, same machine. Any session can run `--stamp`. The marker is a trace that the approval step ran against this exact text, not a signature (see the header of `lib/validators/intent-approval.mjs`). `--stamp` also emits `brief-approved` to `trekexecute-stats.jsonl` under `CLAUDE_PLUGIN_DATA`, falling back to the plugin data dir the yardstick reads, on both the manual and the auto path.
+
 **Failure modes:**
+- `BRIEF_INTENT_NOT_APPROVED` / `BRIEF_INTENT_APPROVAL_STALE` / `BRIEF_INTENT_APPROVAL_INVALID` → `/trekplan` halts (intent-approval gate, above); remedy `/trekbrief --approve <project-dir>`
 - `BRIEF_NOT_FOUND` → consumer halts with a usage message
 - `FM_MISSING` → file has no frontmatter; halt
 - `BRIEF_WRONG_TYPE` → file is not a brief; halt