experiment: choose minimum decision representation

2026-08-12 18:34:18 +01:00
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@@ -2134,3 +2134,85 @@ Vitest run: NO
 Ollama calls: 0
 Dev server disturbed: NO
 Read-only diagnosis: YES
+
+
+### Experiment 60A.2 — Choosing the Minimum Decision Representation
+
+**Branch:** `feature/question-formulation-v0.24`
+**Date:** 2026-08-12
+**Status:** Complete
+**Following:** 60A.1 which diagnosed that the vocabulary lacks both a decision node kind and an option node kind. This evaluates three candidate models against eight criteria to choose the smallest semantically honest representation.
+
+---
+
+## Objective
+
+Choose between three candidates for representing decisions with alternatives:
+
+```
+Decision: Relocate or stay put?
+Option A (Relocate): save £2M, lose 2 engineers, delay 2 months
+Option B (Stay put): retain engineers, avoid disruption, continue paying £2M/year
+```
+
+Three models evaluated:
+- **A** — DECISION + OPTION (new decision node kind + new option node kind)
+- **B** — UNKNOWN + OPTION (reuse existing unknown as decision context + new option node kind)
+- **C** — OPTION PAIR ONLY (option nodes linked by alternative_to, no decision context node)
+
+Not implemented. No code changed. Read-only design evaluation.
+
+---
+
+## Results
+
+### Candidate A (DECISION + OPTION)
+- Semantic honesty: HIGH | Recoverability: FULL | Lifecycle: NATIVE | Question: CLEAN | Consequences: YES | Baseline: CLEAN
+- New primitives: 2 node kinds + 1 edge type + 1 optional field = **4**
+- Semantic overload: NONE
+- Verdict: Satisfies all criteria but adds the most primitives
+
+### Candidate B (UNKNOWN + OPTION) ✅ WINNER
+- Semantic honesty: MEDIUM | Recoverability: FULL | Lifecycle: NATIVE | Question: CLEAN | Consequences: YES | Baseline: WORKABLE
+- New primitives: 1 node kind + 1 edge type + 1 optional field = **3**
+- Semantic overload: LOW (unknown carries both "uncertainty" and "decision context" — natural overlap, not contradictory)
+- Verdict: Smallest model satisfying all five decision-rule conditions
+
+### Candidate C (OPTION PAIR ONLY)
+- Semantic honesty: LOW | Recoverability: POOR | Lifecycle: AWKWARD | Question: WORKABLE | Consequences: YES | Baseline: WORKABLE
+- New primitives: 1 node kind + 1 edge type = **2**
+- Semantic overload: LOW-MEDIUM
+- Verdict: Fails criteria 1 (decision context not recoverable) and 3 (no open/resolved lifecycle support). Minimalism too expensive semantically.
+
+---
+
+## Architectural Choice: B — UNKNOWN + OPTION
+
+### What changes (exact boundary):
+```javascript
+// schema.js additions:
+option: "option"                    // SituationKind enum value
+contained_in: "contained_in"        // SituationRelationship enum value
+is_baseline: z.boolean().optional() // optional on option nodes (not required for v1)
+```
+
+### What does NOT change:
+- `unknown` node kind retains its existing semantics; it now also serves as decision context via the new `option` children pattern
+- All existing statuses, edge types, graph topology rules unchanged
+- Question compatibility uses existing `selectedQuestion` mechanism without extension
+- No migration of existing nodes required
+
+### Decision lifecycle: NATIVE — open/resolved maps to unknown status transitions
+### Additional questions answered:
+1. Is `alternative_to` needed between options? **NO** — shared parent membership implies alternatives.
+2. Is `is_baseline` flag required? **NOT NEEDED YET** — label/consequence patterns carry sufficient signal.
+
+---
+
+Production code changed: NO
+Prompt changed during experiment: NO
+Validator changed during experiment: NO
+Vitest run: NO
+Ollama calls: 0
+Dev server disturbed: NO
+Read-only design evaluation: YES