experiment: define decision closure ownership policy

docs/experiment-60b78.md

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+# Experiment 60B.78 — Decision Closure Ownership Policy (Design Only)
+
+**Date:** 2026-08-15  
+**Branch:** `feature/sufficiency-decision-detection-v0.46`  
+**Preceded by:** Experiment 60B.77 (model-led closure proven by elimination)  
+**Type:** Design analysis — no implementation
+
+## Objective
+
+Choose the correct ownership policy for parent-decision closure when:
+
+```text
+hasRemainingMaterialFactors(decision) === false
+AND
+isUserConfirmationOfNoRemainingUncertainty(answer) === false
+```
+
+The question is not how to implement a fix. The question is whether model-led parent closure should be allowed in that state, or whether the deterministic sufficiency policy owns whether a decision may close.
+
+## Key Findings
+
+### Prompt Ownership (Prompt-Builder Rule 143)
+
+Rule 143 states: "If the currently supported evidence is sufficient to distinguish the options and no such material unresolved factor remains, resolve the existing decision context and do not ask a generic continuation question."
+
+This permits **evidence sufficiency alone** to justify parent closure. It does NOT explicitly require user confirmation. It conflates "model judges represented factors exhausted" with "user confirms nothing else material remains."
+
+### Deterministic Gate (decision-sufficiency.js + apply-proposal.js)
+
+`shouldCloseDecision` requires both:
+1. `countRemainingMaterialFactors === 0`
+2. `isUserConfirmationOfNoRemainingUncertainty(answer)` returns true (bounded CONFIRMATION_PHRASES/PATTERNS matching)
+
+This is the **authoritative** closure policy — it unconditionally sets status=resolved when both conditions are met, with no override mechanism.
+
+### Model-Led Closure Risk
+
+60B.77 proved the model independently proposes terminal closure when resolving its last material factor. When this happens without explicit user confirmation:
+- **Premature-closure risk:** HIGH — contradicts false-open-over-false-closed philosophy
+- **Unrepresented uncertainty possible:** YES — model cannot capture what user knows but hasn't graphed
+- **Bypasses conservative policy:** YES — removes the explicit confirmation step entirely
+
+### Status Semantics
+
+- `known`: directional value determined (TERMINAL_STATUSES)
+- `resolved`: investigation complete, nothing to investigate further (TERMINAL_STATUSES)
+- Both appear in TERMINAL_STATUSES — no existing distinction supports separating "model direction" from "user-confirmed closure" without broader changes.
+
+## Decision
+
+**Choice: B — EXPLICIT CONFIRMATION SHOULD AUTHORITATIVELY GATE CLOSURE**
+
+Rationale:
+1. Conservative false-open philosophy encoded in confirmation phrases must not be overridable by model judgment
+2. Model-led closure was proven (60B.77) to occur without confirmation
+3. Unrepresented material uncertainty is possible
+4. State B exists specifically for this gap — removing it via model-led closure defeats its purpose
+5. False closure cost >> unnecessary questioning cost
+
+## Minimum Corrective Boundary
+
+**Choice: E — PROMPT CLARIFICATION + DETERMINISTIC ENFORCEMENT**
+
+1. Reword rule 143 to require explicit user confirmation matching deterministic gate criteria
+2. Add validation in apply-proposal.js that strips model-proposed terminal closure without explicit confirmation
+
+No schema change required. State B remains reachable when confirmation absent. Model reasoning/direction preservable (can express preferred option without setting resolved status).
+
+## Files Modified
+
+- `docs/experiment-60b78.md` — this file
+- `docs/current-handoff.md` — appended experiment entry
+
+No production code, tests, prompts, schema, or harness changes.