confidence-engine/docs/experiment-60b19.md

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