feat: STOCK V.1 two-mode config family + wire treatment arms to the pin

fox 2026-05-21: characterize substrate-ON under BOTH answer shapes, so
answer_mode is a swept axis, not a single pinned value.

stock_v1.py now exposes STOCK_V1_POLICIES{quote,claim_lattice} +
STOCK_V1_GOVERNANCE_HASHES (quote 5b6ca4c5..., claim_lattice 036a4c79...),
policy_for(mode), and assert_not_drifted(mode). Shared pins (crosslang
OFF, repair OFF, quantifier dry-run, metacognition label-only,
soft-preflight OFF, claim cap 12, v2-acronym-aware) are frozen
identically across modes.

Wire the treatment arms to the pin (the consumer-side step that makes
the freeze real):
  * control_ab    --answer-mode {quote,claim_lattice}
  * control_sweep --arborist-answer-mode {quote,claim_lattice}
Both default claim_lattice (prior behavior), call assert_not_drifted on
non-reasoning runs (halts the sweep if DEFAULT_QUERY_POLICY drifts), and
load the frozen policy_for(mode) instead of an inline
dict(DEFAULT_QUERY_POLICY, ...). Reasoning refs (phase 3) keep their
documented JSON overrides and skip the assert by design (different hash).

jaggedness is left standalone — it is a mode-agnostic retrieval
instrument, coupling it to the answer-policy freeze adds friction with no
correctness gain. Full suite 2528 passed.

docs/stock-v1-config.md

@@ -10,9 +10,21 @@ silently drift across a 3-4 day run. Source of truth:
 The full merkle-agi-dag reverse-RAG SQD / Prometheus-σ recursive-
 falsification substrate, **non-reasoning** and **non-distributed**.
 
+STOCK V.1 is a **two-cell config family** (fox 2026-05-21): the substrate
+is characterized under both answer shapes, so `answer_mode` is a **swept
+axis**, each cell frozen with its own governance hash —
+
+- **`quote`** — prose with inline verbatim quotes; bench leader on raw
+  lexical grounding (~0.54 strict).
+- **`claim_lattice`** — structured JSON claim-lattice (the four-rung
+  ladder); what `control_ab`/`control_sweep` already drive, and the only
+  shape with phase-3 reasoning-variant support built (~0.42 strict).
+
+Everything else below is frozen identically across both modes.
+
 | knob | value | note |
 |---|---|---|
-| `answer_mode` | `quote` | bench leader on raw lexical grounding |
+| `answer_mode` | **swept**: `quote` \| `claim_lattice` | two-cell family |
 | `temperature` / `top_p` / `max_tokens` | `0.1` / `1.0` / `512` | from `DEFAULT_QUERY_POLICY` |
 | `repair_enabled` | `False` | one-shot discipline, no self-heal reprompts |
 | crosslang guard / translate / entity-mask | **OFF** | English-only; sandwich-MT is a separate capability |
@@ -31,19 +43,32 @@ falsification substrate, **non-reasoning** and **non-distributed**.
 arm A (question-only, neutral system prompt; gold text supplied
 identically to both arms per the §4b ruling).
 
-## The one hash
+## The hashes (one per mode)
 
 ```
-governance_policy_hash = 5b6ca4c5e754e96b7e2e8af16a8948dec8d8b2a80b9304df21b1f6d494aade4e
+governance_policy_hash[quote]         = 5b6ca4c5e754e96b7e2e8af16a8948dec8d8b2a80b9304df21b1f6d494aade4e
+governance_policy_hash[claim_lattice] = 036a4c79fd9d381a9ebf54094091c5f4e892793ae3b6dc56f70b8d4921c47455
 ```
 
-This identifies the whole campaign. `bench/stock_v1.py` snapshots the
-live `DEFAULT_QUERY_POLICY`, re-asserts the load-bearing pins, hashes
-the whole effective dict, and `assert_not_drifted()` fails **loudly** if
-that hash ever changes — a mid-campaign edit to `DEFAULT_QUERY_POLICY`
-(a pinned knob *or any other field the hash covers*) stops the harness
-rather than quietly changing what "substrate-ON" means. Re-pinning is a
-deliberate fox-gated bump to V.2, never silent.
+These identify the campaign. `bench/stock_v1.py` snapshots the live
+`DEFAULT_QUERY_POLICY`, re-asserts the load-bearing pins, sets the mode's
+`answer_mode`, hashes the whole effective dict, and
+`assert_not_drifted(mode)` fails **loudly** if that hash ever changes —
+a mid-campaign edit to `DEFAULT_QUERY_POLICY` (a pinned knob *or any
+other field the hash covers*) stops the harness rather than quietly
+changing what "substrate-ON" means. Re-pinning is a deliberate fox-gated
+bump to V.2, never silent.
+
+**Phase 3 (reasoning) note.** Reasoning refs (qwen-think) layer
+documented overrides onto `claim_lattice` inside `control_sweep` (cleared
+JSON stop sequences, 8192-token budget for the reasoning trace,
+empty-output self-heal). Those overrides change the policy, so a
+reasoning run has a *different* governance hash by construction — correct,
+since it is a different phase-3 config. The V.1 drift guard therefore
+covers only the non-reasoning frozen base; reasoning runs skip the assert.
+
+Harnesses select the mode via `--answer-mode` (`control_ab`) /
+`--arborist-answer-mode` (`control_sweep`), default `claim_lattice`.
 
 ## Campaign matrix