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DCS-S1 (proper-noun possession sub-shape expansion) investigation revealed that the recognizer-injector path's `CandidateInitial`-only return type is a substrate-level constraint blocking four Wave-Next sub-shape categories — not just one. ## Two artifacts 1. **`docs/handoff/DCS-S1-FINDING.md`** — investigation result. Of the 21 DCS-refused GSM8K cases, zero are pure S1-only blockers. Acquisition-verb expansion (`collected`, etc.) conflicts with ADR-0131.G.1's branch-disagreement discipline. The right fix is the DCS injector emitting `CandidateOperation(add)`, but the `inject_from_match` return type doesn't allow that. 2. **`docs/decisions/ADR-0170-injector-contract-widening.md`** — scoping ADR. Names the contract change, the four categories it unblocks (DCS-S1 acquisition, A1 currency, A3 multiplicative, A4 temporal), the three load-bearing rules it must preserve (ADR-0131.G.1, SentenceChoice union, admissibility gates), and a 5-step implementation outline. ## Pattern recognised Wave-Next surfaced four schema gaps. All four trace to the same constraint: per-category injectors can only emit `CandidateInitial`. The right next-capability work is ADR-0170 ratification, then a small no-behavior-change PR widening the contract, then per-injector follow-up PRs against the widened contract. That is the actual lift-per-risk path for GSM8K Round-1 closure. ## Test plan Docs-only. No code, no test, no eval, no pack change. ## Cross-references - ADR-0163.D.2 — original parsed_anchors → solver-state ADR - ADR-0131.G.1 — branch-disagreement discipline ADR-0170 preserves - ADR-0167 — parallel teaching-corridor mechanism (independent) - ADR-0167-FOLLOWUPS §7 — Wave-Next findings backlog - WAVE-NEXT-REVISED — parent plan; ADR-0170 is the upstream blocker - PR #369 — A2's schema-refusal artifact (first observation of gap)
141 lines
6.2 KiB
Markdown
141 lines
6.2 KiB
Markdown
# DCS-S1 Finding — Injector Contract Is the Substrate Bottleneck
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**Date:** 2026-05-27
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**Status:** Finding; no implementation. Routes work to ADR-0170.
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**Parent:** `docs/handoff/WAVE-NEXT-REVISED.md`
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**Result:** DCS-S1 (proper-noun possession sub-shape expansion) cannot
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ship meaningful lift on current GSM8K without first widening the
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`inject_from_match` return-type contract. Same schema gap A3
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(multiplicative) and A4 (temporal) identified.
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---
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## What was investigated
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The Wave-Next-Revised plan named **DCS-S1** as the next tractable
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sub-shape: extend the existing v1 `inject_discrete_count_statement`
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injector to cover more of the 21 `discrete_count_statement` refusals
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on the GSM8K train_sample.
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The hypothesis: most DCS refusals are proper-noun possessions whose
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extraction fails for one of a few narrowable reasons (verb whitelist,
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clause-split markers, single-quantity rule). Loosening the matcher +
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extending the injector to cover those would lift several cases.
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## What the data actually shows
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All 21 DCS-refused cases were enumerated and the triggering statements
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inspected. The structural breakdown:
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| Sub-shape pattern in DCS-refused statements | Count |
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|---|---:|
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| Acquisition verb (`collected`, `donated`, `bought`) — not in possession whitelist | ~5 |
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| Multi-clause / enumeration (`and`, `then`, `,`) | ~8 |
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| Pronoun subject (`he`, `she`, `they`) | ~4 |
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| Comparative reference (`twice as many`, `half of`) | ~3 |
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| Anonymous subject (`There are`, `The guests`) | ~3 |
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| Other (modal verbs, copula, multi-verb) | ~4 |
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(Buckets overlap — many cases hit multiple narrowness rules.)
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**Critical observation:** of the 21 cases, **zero** are pure S1-only
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blockers. Every single one has additional blockers downstream in the
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same problem. Even if the DCS injector admitted the first sentence,
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sentences 2/3/4 carry their own refusals.
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Concrete trace — case `gsm8k-train-sample-v1-0023`:
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```
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S1: "Nicole collected 400 Pokemon cards."
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→ would inject Nicole=400 if `collected` were in possession verbs
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S2: "Cindy collected twice as many, and Rex collected half of Nicole and Cindy's combined total."
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→ multi-clause + comparative reference; will refuse on current rules
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S3: question with `If Rex divided...` conditional prefix
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→ conditional prefix recovery exists but answer still requires S2's admission
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```
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Admitting S1 alone does not close the case. The bottleneck moves from
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S1 to S2; no admission-lift is delivered.
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## The architectural blocker
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To admit `"Nicole collected 400 Pokemon cards"` as initial state, three
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edits would be needed:
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1. Add `collected` to `_POSSESSION_VERBS` (matcher narrowness in
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`generate/recognizer_match.py`)
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2. Extend `_locate_possession_verb` in the injector
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3. Add `collect, collects, collected` to `CandidateInitial.__post_init__`
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whitelist in `generate/math_candidate_parser.py`
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**ADR-0131.G.1 explicitly removed `collected/bought/saved/buys/makes`
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from initial-anchor extraction** — they were routed exclusively to
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`ADD_VERBS` (operation extraction) to avoid branch disagreement when
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the same sentence could produce both `CandidateInitial(Sam=5)` AND
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`CandidateOperation(Sam, add, 5)`.
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The solver "defaults from zero for operations" so
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`Sam collected 5 apples. How many does Sam have?` → `0 + 5 = 5`. That
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discipline is load-bearing for wrong=0 in the regex path.
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The right architectural fix is not to break ADR-0131.G.1. It's to teach
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the **DCS injector** to emit `CandidateOperation(add)` for acquisition
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verbs — the same kind of state-introducing operation the parser
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already emits for them.
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**But:** `inject_from_match`'s return type is
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`tuple[CandidateInitial, ...]`. It cannot emit `CandidateOperation`.
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Widening the contract is the prerequisite.
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## The pattern — fourth time this gap appears
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Wave-Next surfaced four schema gaps. All four trace back to the same
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substrate-level constraint: the recognizer-injector path can only
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emit `CandidateInitial`.
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| Brief | What needed emission | Available type | Blocker |
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|---|---|---|---|
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| **A2** rate_with_currency | `CandidateRate` (carries `Rate(value, num_unit, den_unit)`) | None — `Rate` not in `SentenceChoice` union | Schema gap (PR #369) |
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| **A3** multiplicative_aggregation | `CandidateInitial(outer × inner)` OR `CandidateOperation(multiply)` | `CandidateInitial` works for product semantics; but other cases need composition | Half-blocked |
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| **A4** temporal_aggregation | `CandidateOperation(apply_rate, ...)` | `apply_rate` primitive doesn't exist | Algebra-level gap |
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| **DCS-S1** | `CandidateOperation(add)` for acquisition verbs | Injector returns only `CandidateInitial` | Schema gap (this finding) |
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This is no longer four separate sub-shape problems. It's **one substrate
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bottleneck affecting all four categories**. The right artifact is a
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contract-widening ADR — see [ADR-0170](../decisions/ADR-0170-injector-contract-widening.md).
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## What this PR ships
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- This finding doc (`docs/handoff/DCS-S1-FINDING.md`)
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- `docs/decisions/ADR-0170-injector-contract-widening.md` — the scoping
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ADR that names the contract change and the four categories it unblocks
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What this PR does NOT ship:
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- Any DCS-S1 implementation (it's blocked on ADR-0170)
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- Any matcher/extractor edits
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- Any test changes
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- Any pack changes
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## Recommended next move
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ADR-0170 ratification, then a small focused PR implementing the
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contract widening (no behavior change, type-only). Then a follow-up
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wave (DCS-S1 acquisition, A1 currency, A2 rate, A3 multiplicative,
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A4 temporal) can ship in parallel — each as a focused injector PR
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against the widened contract.
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That's the actual lift-per-risk path. Until ADR-0170 lands, no
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recognizer-injector work other than `CandidateInitial`-only narrow
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possession can ship cleanly.
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## Cross-references
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- [WAVE-NEXT-REVISED](./WAVE-NEXT-REVISED.md) — parent plan; needs an
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update pointing to ADR-0170 as the prerequisite
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- [ADR-0170](../decisions/ADR-0170-injector-contract-widening.md) — the
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scoping ADR this finding routes to
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- PR #369 (A2) — first observation of the gap; documents `Rate`
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extension steps
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- ADR-0131.G.1 — the original branch-disagreement discipline that
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forces acquisition verbs to be operations, not initials
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- ADR-0167-FOLLOWUPS §7 — Wave-Next findings backlog
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