fix(#3206): define "explicit evidence" inline at verifier 5b; repair stale honest-verifier cites (#3435)

* fix(#3206): define "explicit evidence" inline at verifier 5b; repair stale honest-verifier cites

Step 3 item 5b abstained on non-inferable (backstop) truths "unless
confirmed by explicit evidence" with the term undefined — its definition
lived only in the non-included gsd-core/references/honest-verifier.md,
behind a stale bare `references/` cite that 404s. Undefined, the term
falls back to presence + wiring, the exact false-pass the #1154
abstention protocol refuses.

- 5b: inline the compressed definition (a passing wired
  held-out/property-based test or directly observed behavior; presence +
  wiring never qualifies) and fix the cite. +84 B on the rewritten line;
  file lands at 49,151 of the 49,152 LARGE cap.
- verifier-phase-gates.md (already <required_reading>): gains the
  backstop-abstention reporting contract — AFK completion line
  ("complete with N unverified non-inferable checks", never silent,
  never a halt) and reason-distinctness (insufficient_spec vs manual-UAT
  human_needed). New content, no relocation of measured prose.
- 5c (line 204) and MVP-mode (line 644) bare cites repaired to
  gsd-core/references/ (+9 B each).
- Drift acks per ADR-2719 §4; two entries merge-appended into existing
  fragments (two ack sources may never name the same path).
- Changeset fragment with the sanctioned pr: 0 placeholder (post-create
  backfill).

Sibling census at next@7976b1ca0: 7 bare-cite instances in 4 agent
files; the 3 in gsd-verifier.md are fixed here, gsd-executor.md:429,439
and gsd-doc-synthesizer.md:20,176 stay with the epic #1891 follow-up.

Refs #1891

* chore(#3206): set changeset fragment pr to 3435

* fix(#3206): drop stale emitted-drift-ack entries that trip the ADR-2719 ratchet

The round's ack bookkeeping explained ripples that were already
self-attributed, so `tests/emitted-attribution.test.cjs` failed
deterministically on the PR head with 5 stale acknowledgments.

`agents/gsd-verifier.md` and `gsd-core/references/verifier-phase-gates.md`
appear directly in `git diff --name-only`, so PROVENANCE_RULES attributes
their emitted deltas without an ack; `agents/gsd-verifier.agent.md`,
`agents/gsd-verifier.toml` and `agents/subagents/gsd-verifier.md` are
derived emissions of a changed source and are attributed the same way.
None of the five entries could ever be consumed, so all five were stale.

Removed: the whole `3206-verifier-explicit-evidence.json` fragment (all
four entries) and the `#3206 append` to `0000-legacy-migration.json`.

Deliberately KEPT: the `#3206 append` to
`1955-verifier-coincidental-reliance.json`. Its `gsd-verifier.md` entry is
consumed by the size-growth ratchet, not the hash pass — the agent grew
49049 -> 49151 bytes, and `diffEmitted` treats a base-identical ack as
spent and excludes it from `ackEntries`. Reverting that append as well
turns the stale-ack failure into `1 file(s) grew without an
acknowledgment` (verified both ways locally).

* fix(#3206): compress 5b and re-acknowledge growth after rebase onto next

The rebase onto next (159145435, PR #3558) invalidated two things at once:

- #3558 grew agents/gsd-verifier.md to 49,098 bytes, leaving 54 bytes of
  LARGE-cap headroom where this PR's +102 no longer fits. Compressed the
  5b rewrite to +34 net by dropping the trailing honest-verifier cite —
  superseded by the now-inline definition; honest-verifier.md stays
  cited at the adjacent 5c line. File lands at 49,150 (2 under the cap).
- #3558 deleted tests/emitted-drift-acks/1955-verifier-coincidental-
  reliance.json, which carried this PR's growth acknowledgment, and its
  own 3409 fragment now names gsd-verifier.md. Re-homed the #3206 growth
  ack as an append to that entry (two ack sources may never name the
  same path).

The changeset is updated to match: two bare references/ cites repaired
(5c honest-verifier.md, MVP-mode verify-mvp-mode.md), the third (5b's)
superseded by the inline definition rather than repaired.

Reversion controls: restoring the uncompressed 5b fails
agent-size-budget.test.cjs (LARGE hard cap); reverting the ack append
fails emitted-attribution.test.cjs (differential attribution over the
real tree, GSD_EMITTED_BASE=upstream/next). Both re-verified green at
this tree: 213/213 (size + attribution), 992/992 across the 14 suites
reading the touched files.

Refs #3206

* test(#3206): pin the 5b explicit-evidence definition and cite resolution

* fix(#3206): pin regression tests to the shipped contract text

---------

Co-authored-by: sim <sim@local>

agents/gsd-verifier.md

@@ -201,8 +201,8 @@ For each truth:
    - A pre-existing test exercises the transition/invariant and passes (confirm via Step 7b's single-named-test path) → ✓ VERIFIED.
    - No such test exists, or it can't run without a server/state mutation → ⚠️ PRESENT_BEHAVIOR_UNVERIFIED. Emit a human-verification item (Step 8) and do not count it toward the verified score (Step 9).
    - An accepted override (Step 3b) carries the truth as PASSED (override), exactly as it does for a FAILED truth.
-5b. **Non-inferable (`backstop`) truths:** a `verification: backstop` truth (via `truthVerification()`) abstains unless confirmed by explicit evidence — mark `insufficient_spec` -> a human-verification item -> `human_needed`. See `references/honest-verifier.md`.
-5c. **Reliance check (advisory, #1955).** Before finalizing a ✓ VERIFIED truth, ask *why* it holds. Classify the evidence already recorded, not your confidence in it. Endogenous, and so weaker than the exogenous `backstop` tag (`references/honest-verifier.md`) — advisory for exactly that reason. Flag `coincidental-reliance` when the evidence names one of: **undeclared-precondition** (state nothing in the phase's artifacts or a declared prerequisite guarantees), **incidental-ordering** (an order or side effect nothing in the code enforces), **fixture-only** (the test's own setup establishes the precondition; the production path has no equivalent). **Do NOT flag:** a precondition the code establishes or explicitly defaults; ordering the code enforces (await, explicit sequencing); a fixture merely supplying input the real caller also supplies; unease naming no specific state, ordering, or fixture. Out of scope: ⚠️ PRESENT_BEHAVIOR_UNVERIFIED and ⚠️ `insufficient_spec` (already routed to human), and PASSED (override) truths. Record `✓ VERIFIED (coincidental-reliance)` and add a `coincidental_reliance_items` entry. **Advisory only — not the score, not the status, and never a human-verification item** (Step 9 rule 2 would flip a passing phase to `human_needed`). The usual fix: promote the hidden assumption into a declared precondition.
+5b. **Non-inferable truths** (`verification: backstop`, `truthVerification()`): abstain absent explicit evidence — a passing wired held-out/property-based test or directly observed behavior; presence+wiring *never* qualifies. Mark `insufficient_spec` -> human-verification item -> `human_needed`.
+5c. **Reliance check (advisory, #1955).** Before finalizing a ✓ VERIFIED truth, ask *why* it holds. Classify the evidence already recorded, not your confidence in it. Endogenous, and so weaker than the exogenous `backstop` tag (`gsd-core/references/honest-verifier.md`) — advisory for exactly that reason. Flag `coincidental-reliance` when the evidence names one of: **undeclared-precondition** (state nothing in the phase's artifacts or a declared prerequisite guarantees), **incidental-ordering** (an order or side effect nothing in the code enforces), **fixture-only** (the test's own setup establishes the precondition; the production path has no equivalent). **Do NOT flag:** a precondition the code establishes or explicitly defaults; ordering the code enforces (await, explicit sequencing); a fixture merely supplying input the real caller also supplies; unease naming no specific state, ordering, or fixture. Out of scope: ⚠️ PRESENT_BEHAVIOR_UNVERIFIED and ⚠️ `insufficient_spec` (already routed to human), and PASSED (override) truths. Record `✓ VERIFIED (coincidental-reliance)` and add a `coincidental_reliance_items` entry. **Advisory only — not the score, not the status, and never a human-verification item** (Step 9 rule 2 would flip a passing phase to `human_needed`). The usual fix: promote the hidden assumption into a declared precondition.
 6. Determine truth status
 
 ## Step 3b: Check Verification Overrides
@@ -642,7 +642,7 @@ Deferred items are informational only — they do not require closure plans.
 
 **VERIFICATION.md output structure under MVP mode:**
 
-1. Top-level "User Flow Coverage" table: each step of the user story → expected → evidence in codebase → status. (Format defined in `references/verify-mvp-mode.md`.)
+1. Top-level "User Flow Coverage" table: each step of the user story → expected → evidence in codebase → status. (Format defined in `gsd-core/references/verify-mvp-mode.md`.)
 2. Standard technical-check sections (API verification, error handling, etc.) follow below — only if the user flow coverage is complete.
 
 **User Story format guard:** Apply via the centralized verb instead of inlining the regex: