feat(circuit): SynapticCircuit bedrock layer (v0.3) — Beta prior, prediction-error propagation, earned lighthouse floor

[mazze93]

Summary

Replaces the static W_base(s) constant in the decay formula with a mutable Beta-distributed prior, and introduces the bidirectional prediction-error propagation substrate the v0.3 decay layer was missing.

• Sources/SynapseCore/Circuit/CircuitTypes.swift — Prior, SynapticNode, CircuitEdge, CircuitConstants, plus all Sendable output value types (ForwardPassResult, BackwardPassResult, CircuitSnapshot, FaultInjectionReport, CalibrationReport).
• Sources/SynapseCore/Circuit/SynapticCircuit.swift — Swift actor with forward/backward pass, connectivity cache, dynamic lighthouse floor, snapshot-first fault injection. Ordering enforced internally via lastForwardPassNumber.
• Sources/SynapseCore/FaultInjection/FaultInjectionSuite.swift — calibration suite producing empirical recommendations for ROT_LAMBDA_AMPLIFIER and ROT_CAUTERIZE_THRESHOLD.

Architecture Decision Records

• ADR-002 — W_base(s) → mutable Beta prior. connectivity_factor(s) derived from edge topology. Prediction error becomes a first-class learning signal.
• ADR-003 — Lighthouse floor = prior.mean × 0.4. The floor is earned, not granted. Lighthouse misdesignation becomes self-correcting.
• ADR-004 — Prediction error joins λ(s, t) as a dynamic decay amplifier alongside (not replacing) rot scoring. Two orthogonal failure modes captured independently.

Full ADRs in docs/adr/. Integration guide for SynapseWeightState consumption in docs/adr/INTEGRATION.md.

Scope discipline

No existing files modified. SynapseCore.swift, SynapseWeightState.swift, RavenRenderer.swift, the CLI, the SwiftUI app — all untouched. This PR is bedrock only; the consumer-side wiring (replacing W_base in SynapseWeightState.decayWeight) is the next PR.

Known threats (MAESTRO)

Documented in ADR-002 risk table:

Threat	Mitigation
T1 — prior poisoning	Learning rate decay; evidence weight cap (100)
T2 — error flooding	Minimum α floor (1.0); backward-pass ordering guard
T3 — lighthouse ossification	Dynamic floor (ADR-003) + FaultInjectionSuite.auditLighthouses
T4 — timing side-channel	Actor isolation; no internal scheduling
T5 — schema drift	schemaVersionHash in CircuitSnapshot

Out of scope for this PR

• SynapseWeightState integration — separate PR, integration recipe in docs/adr/INTEGRATION.md
• SynapseManager backward-pass wiring — v0.4
• Persistence of CircuitSnapshot to disk — needed before v1.0; not blocking the bedrock
• Package.swift bump to swift-tools-version:6.0 for strict concurrency — recommended follow-up, code is already actor-isolated and Sendable-compliant

Test plan

• CI build passes on macos-15 (Swift 5.8+ toolchain)
• Existing BayesianConvergenceTests continue to pass (no changes to consumed surfaces)
• Manual: instantiate SynapticCircuit, register a few nodes, run forwardPass() → backwardPass(observations:) → confirm BackwardPassResult.predictionErrors reflects |predicted − observed|
• Manual: run FaultInjectionSuite.runFullSuite() against a small circuit and confirm CalibrationReport.formattedSummary produces a sensible recommendation

Bedrock unit tests will follow in a separate PR — keeping this one to net-new files and zero modifications for review clarity.

https://claude.ai/code/session_0193B19zr8PsbvJMphKxufw4

---

Generated by Claude Code

[coderabbitai]

Important

Review skipped

Review was skipped due to path filters

⛔ Files ignored due to path filters (8)

• CLAUDE.md is excluded by none and included by none
• Sources/ContextSynapseApp/RegionModel.swift is excluded by none and included by none
• Sources/SynapseCore/Circuit/CircuitTypes.swift is excluded by none and included by none
• Sources/SynapseCore/Circuit/SynapticCircuit.swift is excluded by none and included by none
• Sources/SynapseCore/FaultInjection/FaultInjectionSuite.swift is excluded by none and included by none
• docs/adr/ADR-002-bidirectional-prediction-error-propagation.md is excluded by none and included by none
• docs/adr/ADR-003-004-lighthouse-floor-and-decay-amplifier.md is excluded by none and included by none
• docs/adr/INTEGRATION.md is excluded by none and included by none

CodeRabbit blocks several paths by default. You can override this behavior by explicitly including those paths in the path filters. For example, including **/dist/** will override the default block on the dist directory, by removing the pattern from both the lists.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: fc248a7b-9ffd-475e-b05d-bae5ded05b74

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

❌ Error creating Unit Test PR.

• Create PR with unit tests
• Commit unit tests in branch claude/circuit-bedrock-v0.3

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Note

Unit test generation is a public access feature. Expect some limitations and changes as we gather feedback and continue to improve it.

---

Generating unit tests... This may take up to 20 minutes.

[coderabbitai]

✅ Created PR with unit tests: #13

[coderabbitai]

Note

Unit test generation is a public access feature. Expect some limitations and changes as we gather feedback and continue to improve it.

---

Generating unit tests... This may take up to 20 minutes.

[coderabbitai]

No files have been changed in this PR. Unable to generate unit tests.