docs: record bounded structural context admission

2026-08-13 12:49:42 +01:00
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+# Experiment 60B.19 — Bounded Structural Context Admission
+
+**Branch:** `feature/reasoning-context-compatibility-v0.28`  
+**Date:** 2026-08-13  
+**Status:** COMPLETE  
+**Type:** BOUNDED IMPLEMENTATION
+
+## Objective
+
+Replace the blocked 60B.16 global reasoning-compatibility fallback with the 60B.18 boundary:
+
+- run structural context fallback only for **newly-added unresolved unknowns**;
+- run it only when the **full proposal is known but before graph mutation**;
+- use the **pre-update `activeUnknownNodeId`** as the decision-context identity;
+- preserve that same-turn admission through later validation without changing generic compatibility semantics for unrelated nodes.
+
+## Why the global 60B.16 integration was removed
+
+60B.17 established that the structural Route A / Route B predicate itself was useful, but its **global integration layer was too broad**. Applying fallback inside generic compatibility checks caused 8 `apply-proposal` regressions by changing behaviour for unrelated pre-existing and later-selected unknowns.
+
+The secondary defect was that later compatibility re-checks could lose the original decision-context identity and validate against the wrong active node.
+
+## Implemented boundary
+
+Structural context fallback now runs only at the **pre-mutation proposal boundary**:
+
+- eligibility is limited to `proposal.addedNodes` where:
+  - `kind === "unknown"`
+  - `status !== "resolved"`
+- the original context identity is:
+  - `situationGraph.activeUnknownNodeId`
+- the original context pattern is recovered from the **pre-update graph**
+- structural admission is only relevant when:
+  - `activePattern === "decision"`
+
+No pre-existing unknowns, updated existing nodes, resolved nodes, or later-selected targets enter the fallback by scope.
+
+## Route A / Route B
+
+### Route A
+
+Admit a newly-added unresolved unknown when its `parentId` / ancestor chain reaches the original active decision context node.
+
+### Route B
+
+Admit a newly-added unresolved unknown when:
+
+- `X --(may_cause | causes | affects)--> option Z`
+- `Z --contained_in--> active decision D`
+- `D.id === pre-update activeUnknownNodeId`
+
+### Explicit non-qualifiers
+
+These do **not** establish Route B:
+
+- `supports`
+- `measures`
+- `depends_on`
+- arbitrary graph connectivity
+
+## Local admitted-node tracking
+
+No schema field was added.
+
+Within `applyValidatedProposal()` only, the implementation now maintains a local in-memory set of structurally admitted node IDs for same-turn newly-added unresolved unknowns.
+
+That set is then threaded into later compatibility checks so the exact already-adjudicated diagnosis→decision mismatch is not rejected again during post-mutation selection/result validation.
+
+This does **not**:
+
+- rewrite intrinsic node pattern;
+- make the node universally compatible;
+- disable non-pattern validations;
+- change question targeting, scoring, materiality, prompt, or schema.
+
+## Regression restoration
+
+Focused suite:
+
+- `npx vitest run tests/graph/reasoning-context-compatibility.test.js` → **PASS (14/14)**
+
+Combined bounded verification:
+
+- `npx vitest run tests/graph/apply-proposal.test.js tests/graph/reasoning-context-compatibility.test.js` → **PASS (96/96)**
+
+This restored the 8 60B.17 regressions by construction:
+
+- pre-existing unknowns no longer enter fallback;
+- later-selected 60B.11 fixtures no longer trigger fallback merely because they are chosen after mutation;
+- later compatibility re-checks now use the preserved original reasoning-context node identity instead of selected-child drift;
+- generic compatibility semantics remain unchanged outside the bounded same-turn admission class.
+
+## What remains unproven
+
+Still unproven until the exact live regression is rerun:
+
+- the precise 60B.12 client-retention continuation case in a live end-to-end path where the model introduces the factor and the final selected target preserves that same ready material unknown.
+
+## Production code changed
+
+YES — `lib/graph/apply-proposal.js`
+
+## Tests changed
+
+YES — `tests/graph/reasoning-context-compatibility.test.js`
+
+## Prompt changed
+
+NO
+
+## Schema changed
+
+NO
+
+## Question targeting changed
+
+NO
+
+## Materiality changed
+
+NO
+
+## Selection scoring changed
+
+NO
+
+## Ollama calls
+
+0
+
+## Live API calls
+
+0