core/docs/sessions/SESSION-2026-05-26-corridor-closure.md

Session 2026-05-26 — Corridor Closure: First Measurable Lift on GSM8K

Status: Complete ✓ Closed: 2026-05-26 (evening PST) Headline: Closed the math architecture corridor end-to-end (Phase A → B → C → D + operator ratification) and produced the first non-zero correct count on the GSM8K train_sample baseline. Shipped the Workbench UI shell + chat surface concurrently.

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TL;DR

14 PRs merged + 1 issue filed in a single session. The math architecture went from 0/50/0 (zero correct, fifty refused, zero wrong) to 3/47/0 — the first lift the engine has ever produced on GSM8K — with the wrong = 0 invariant preserved by construction at every step. The Workbench went from "doctrine only" to "fully operational end-to-end" (read-only API + design substrate + frontend shell + live chat surface with trace drawer).

The day demonstrated that the "decodes, not generates" thesis is actionable as a corridor: operator-authored exemplars → engine-derived recognizers → operator ratification → measurable admissibility lift, with no algebra changes, no pack mutations, no hidden normalization.

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Merged PRs (in chronological order)

#	Title	SHA
#288	chore(contemplation): CI run 2026-05-26T103018Z	ddb94d3
#290	fix(W-025): polish contemplation-quality eval lane follow-ups	8829529
#291	docs(L11): ADR-0161 — HITL async queue (proposed)	0909ef2
#292	feat(W-026): read-only workbench API (ADR-0160 Phase 1)	8a24ebe
#293	docs(workbench): ADR-0162 — Workbench Design System v1 (proposed)	8a24256
#294	docs(math): ADR-0163 — path to GSM8K mastery (proposed)	8b3314f
#295	feat(workbench-ui): design system v1 scaffold (ADR-0162 Branch 1)	(squash)
#296	feat(ADR-0161.1): core teaching queue list|show + fix + R1..R5	ec5d6f5
#297	feat(ADR-0163.A): refusal taxonomy lane — shape categorization	5b4dcb1
#298	feat(ADR-0163.B.1): exemplar corpora — three categories	1bff568
#299	feat(W-027): Workbench frontend shell — five-region grid	cdead69
#301	feat(ADR-0163.C): contemplation ingests exemplars + DerivedRecognizer proposals	08c5e0e
#302	feat(ADR-0163.D): wire ratified RecognizerSpecs into math_candidate_graph	e9b7eb0
#303	feat(W-028): chat surface + trace drawer (ADR-0160 Phase 3)	a612038
#304	chore(ratify): accept three Phase C exemplar_corpus recognizers (round 1)	062d53f

Plus issue #300 — ingest/gate.py versor_condition margin bug, discovered during Tier 1 manual GSM8K iteration.

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What landed by fork

Fork A — Math Architecture (ADR-0163 corridor)

The corridor closed end-to-end in a single session:

• Phase A (PR #297) — evals/refusal_taxonomy/ lane. Categorized the 50-case GSM8K train_sample refusal histogram into 9 disjoint shape categories + UNCATEGORIZED. 72% categorized (target was 50%). Top three by count: descriptive_setup_no_quantity (17), temporal_aggregation (4), rate_with_currency (3). Doctrine encoded as runtime guards (no LLM imports test, ≥3 evidence-cite rule per category).
• Phase B (PR #298) — teaching/admissibility_exemplars/ carrying 60 hand-authored exemplars across three categories (20 each). Each exemplar binds a statement to an expected_graph payload following a per-category schema. Seven author_note entries surfaced schema gaps for downstream review.
• Phase C (PR #301) — teaching/recognizer_synthesis.py distils each Phase B corpus into a RecognizerSpec. Synthesis is deterministic, narrower-not-broader, rules-only (no LLM / no embeddings). Phase C also extended teaching/replay.py with run_admissibility_replay_gate that runs cognition + G1..G5+S1 + GSM8K train_sample and auto-rejects any candidate that would lift wrong > 0 even by one. Three pending proposals landed in the proposal log.
• Phase D (PR #302) — generate/recognizer_registry.py (pure projection over the proposal log; only state="accepted" + kind="exemplar_corpus" entries enter) + generate/recognizer_match.py (per-category rules-only matchers that honor the Phase C narrowness rule) + a single-edit guard at generate/math_candidate_graph.py:455-470. Skip-only by construction — recognized statements contribute zero math state, so the Cartesian product is byte-identical to "this statement was never there," preserving wrong = 0 at the wiring layer.
• Phase D ratification (PR #304) — operator accepted all three pending proposals via core teaching review --accept. The ratified registry returned len = 3.

First measured lift — GSM8K train_sample (50 cases, post-ratification)

correct: 3   (up from 0 — first non-zero correct count ever)
refused: 47  (down from 50)
wrong:   0   (unchanged — the invariant holds)

exit_criterion: { correct_min: 10, wrong_max: 0, passed: false }

The three lifted cases:

case_id	answer	question excerpt
gsm8k-train-sample-v1-0014	240	Bob can shuck 10 oysters in 5 minutes. How many oysters can he shuck in 2 hours?
gsm8k-train-sample-v1-0018	16	Xavier plays football. During 15 minutes Xavier can score 2 goals on average. How many goals on average...
gsm8k-train-sample-v1-0042	30	Ella has 4 bags with 20 apples in each bag and six bags with 25 apples in each bag. If Ella sells 200 apples, how many apples does she have left?

Capability-axis floor preserved: G1..G5 + S1 all report wrong = 0 post-ratification, byte-identical to the pre-Phase-D baseline.

Unexpected positive observation: none of the three lifts are "pure descriptive_setup_no_quantity" cases. They all involve temporal or aggregation framings where the previously-refusing statement gets skipped and the question + remaining statements carry enough math for the existing solver to produce the right answer. This suggests Phase D's skip-only wiring is doing more useful work than the projection suggested, and that a Phase B round 2 (more shape categories from the uncategorized 14) may be a more direct path to clearing Round 1 exit (correct ≥ 10) than the originally-planned Phase D.2 (parsed_anchors solver plumbing).

Fork B — Workbench UI (ADR-0160 + ADR-0162 + W-026..W-028)

The Workbench is fully operational end-to-end:

uv run core workbench api          # http://127.0.0.1:8765
cd workbench-ui && pnpm dev        # http://127.0.0.1:5173

What ships:

• W-026 (PR #292) — read-only HTTP API (workbench/api.py + workbench/readers.py + workbench/schemas.py + workbench/server.py). Seven GET endpoints + one whitelisted POST (/evals/run for the contemplation_quality lane only). Path-traversal protection, MAX_ARTIFACT_BYTES guard, single-operator concurrency lock on eval runs, request logging gated by CORE_WORKBENCH_QUIET env var.
• ADR-0162 (PR #293) — design system doctrine: semantic tokens, dark-only theme, motion rules ("reveals structure, not cognition"), StableJsonViewer six invariants, empty/error/loading state contracts, keyboard-first contract, five-region shell, v1 component map, explicit no-go list.
• Branch 1 (PR #295) — workbench-ui/ scaffold with self-hosted Inter + JetBrains Mono, generated tokens.ts mirror from tokens.css, StableJsonViewer with all six invariants tested, enum-bound badge primitives (EpistemicStateBadge, NormativeClearanceBadge, ReviewStateBadge, GroundingSourceBadge), and a /preview route as the design baseline. Build-time enum-coverage test parses core/epistemic_state.py + teaching/proposals.py via Python AST and asserts 1:1 badge coverage; adding an enum value on the Python side without updating the badge fails the test loud.
• W-027 (PR #299) — five-region grid shell (TopBar / LeftNav / MainSurface / RightInspector / StatusFooter), ten empty routes each with copy-CLI affordances, live StatusFooter consuming useRuntimeStatus() (color + label encoding of mutation_mode, click-to-copy git_revision, amber-on-warning checkpoint_revision with ADR-0157/0158 inline note), CommandPalette upgrade with three real commands + fuzzy search, ApiErrorBoundary for WorkbenchApiError, schema-drift sentinel via scripts/dump-api-schemas.py.
• W-028 (PR #303) — the first route with real content. /chat route with PromptComposer (⌘/Ctrl+Enter submit, Esc clear, 4096-char cap), ResponseCard, EvidenceStrip (5 enum-bound badges visible at a glance — grounding source, epistemic state, normative clearance, refusal indicator, mutation/checkpoint), TraceDrawer with three layers (structured panels, StableJsonViewer, raw payload behind <details> with downloadable .json). Server-side POST /chat/turn with module-level threading.Lock, 64 KiB body cap, returns full ChatTurnResult carrying surface/walk_surface/articulation_surface distinctly per docs/runtime_contracts.md.

Fork C — HITL Queue (ADR-0161 + L10b followups)

• ADR-0161 (PR #291) — HITL async queue scope ratified. Five sub-questions answered with the narrowest commitment compatible with existing ADR-0057 / 0151 / 0152 / 0155 machinery: queue is a derived view over the proposal log + contemplation runs, no new persistence file, three operator surfaces (PR / workflow_dispatch / CLI), pending cap 256, no wall-clock expiry, only repo owner ratifies.
• Step 1 (PR #296) — core teaching hitl-queue list|show read-only projection (renamed from core teaching queue list|show after I caught a namespace collision with the existing Phase 1.2 gap-promotion command). derive_queue() is a pure function over the proposal log; find_queue_item() supports exact + prefix matching; CLI returns formatted human view or JSON.

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Things discovered along the way

Tier 1 manual iteration falsified an assumption

Earlier in the session I described manual teaching-chain iteration as a path to lift GSM8K cases. Empirical probing showed otherwise: core teaching propose writes to the cognition corpus, but the math admission path is independent — generate/math_candidate_graph.py refuses on its own admission surface, never consulting the teaching corpus. Teaching chains don't lift math cases; only candidate_graph admissibility expansion does (which is ADR-0163's whole point). The manual iteration was the right exercise even though the path it suggested was wrong: it falsified the assumption fast and refocused the session on the corridor.

ingest/gate.py versor_condition margin bug (issue #300)

During Tier 1 probing of Tom has 5 apples. He gives 2 to Sarah. How many does Tom have?, the engine raised a RuntimeError: Injection produced non-versor field: condition=2.12e-06 from ingest/gate.py:346. Bisected the trigger: requires (a) a declarative statement with a quantity, (b) a transfer phrase with to <recipient>, and (c) a "How many" question. Both observed condition values (1.02e-06, 2.12e-06) cluster within 3× of the 1e-6 threshold — normalize_to_versor() is almost closing and missing by a small margin on this token mix. Per CLAUDE.md, the threshold doesn't move; the construction boundary does. Filed as a separate bug, not in scope for the corridor work.

Phase D's skip-only wiring did more than projected

The Phase D PR projected 3 cases lifting under skip-only — primarily through descriptive_setup_no_quantity admissions where the remaining math is solvable by existing G1..G5+S1 admission. Empirically all three lifts were in cases involving rate/temporal framings: the recognizer skipped the previously-refusing statement, the question and remaining statements together carried enough math for the solver to produce the correct answer. This is a forward note for the math fork's next-move planning — Phase D.2 (parsed_anchors solver plumbing) may not be the highest-leverage next step.

Code review discipline transferred across agents

Every PR opened today got a mastery-level review. The review pattern that emerged:

1. Verify locally (run tests, build, smoke check)
2. List 5–10 items at mastery level (the pattern to keep for subsequent branches)
3. List 0–5 non-blocking forward notes (the pattern to track but not block on)
4. Verdict (approve / blocker / forward-action)
5. Cross-references checked

This pattern caught real regressions (Gemini's gap-queue namespace collision in #296) and real architectural framings (Codex's "skip-only by construction" naming in #302). When the agent addressed feedback in a follow-up commit, the same pattern verified the fix. The pattern is now durable; future sessions can use the same shape.

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Operator-side actions taken

When	Action
Mid-session	Removed the required_pull_request_reviews policy on main (kept the verify pinned lane SHAs status check). Authorized in-session by the operator. All later merges flowed through this looser gate.
Late session	Ran core teaching propose-from-exemplars against each of the three Phase B corpora (via Opus 4.7's first commit on PR #302) to land the three pending proposals in the live log.
Late session	Operator ratified all three Phase C recognizers via core teaching review --accept. PR #304 captured the resulting log transitions.
Late session	Filed issue #300 — ingest/gate.py versor_condition margin bug.

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What's NOT done (deferred to future sessions)

• Phase E as briefed — the GSM8K train_sample re-baseline harness (versioned baselines under evals/gsm8k_math/train_sample/v1/baselines/, workflow_dispatch + nightly schedule, LiftReport schema, append-only history). Brief ready to paste; not yet dispatched.
• Phase D.2 / parsed_anchors solver plumbing — would convert rate_with_currency and temporal_aggregation recognitions into solver state. Scope-uncertain after the empirical observation that skip-only already produces some rate/temporal lifts; worth measuring more carefully before scoping.
• Phase B round 2 — three more shape categories from the Phase A uncategorized tail (14 statements). Likely candidates: comparative_with_unit, fractional_rate_of_change, indefinite_quantity, nested_question_target. Operator picks.
• W-029 proposal queue UI — make the HITL queue visible in the Workbench (the three Phase D proposals are in the live log; W-029 surfaces them in the UI).
• W-030 eval center UI — failures-first layout per the vision doc.
• W-031 replay theater UI — original vs replay side-by-side, trace_hash comparison.
• ADR-0161 Steps 2–5 — backpressure (pending-count cap + queue_full reports), submission invariants (duplicate, dependent_on_pending), workflow_dispatch extension to reject/withdraw, embed queue summary in contemplation PR body.
• Issue #300 — ingest/gate.py versor_condition margin fix.

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Architectural state at session close

The substrate is complete enough that the next round can run end-to-end automatically:

Phase B round 2  →  3 new exemplar corpora authored
        ↓
Phase C  →  contemplation runner ingests; emits 3 new RecognizerSpec proposals
        ↓
        (replay gate auto-rejects anything that would lift wrong > 0)
        ↓
Phase D  →  proposals appear in the HITL queue; operator inspects + ratifies
        ↓
        (skip-only wiring + ratified registry both already on main)
        ↓
        next GSM8K eval shows next round of lift, wrong=0 invariant intact

That loop, once you decide to run it, is the math architecture working as designed. Today we proved the loop closes. Future rounds widen.

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Cross-references

• ADR-0163 — Path to GSM8K mastery
• ADR-0162 — Workbench Design System v1
• ADR-0161 — HITL async queue
• ADR-0160 — CORE Workbench v1
• Master plan post-substrate-audit — superseded by this session for the math + workbench forks
• docs/PROGRESS.md — capability-roadmap tracker; this session adds the math-corridor closure entry

Memory cross-references

• thesis-decoding-not-generating — the load-bearing thesis that this session demonstrated as actionable
• feedback-address-critiques-dont-waive — applied consistently across mastery-level reviews
• feedback-cleanup-as-you-find — stale worktrees and merged branches cleaned at session close
• feedback-adr-cross-reference-discipline — every new ADR cross-references existing substrate
• feedback-no-timelines — phases sequenced by prerequisite, not date