nfemmanuel/iranti

Bundle 3: A4 plan proposal on handshake

Handshake now returns a deterministic PlanProposal derived from task string, inferred task type, and any interrupted session checkpoint. Hosts can surface a 5-step plan to the user before starting complex work.

Changes

• Pure detectPlanSignals() matches 8 signal types (ship/implement/refactor/fix/audit/migrate/test/deploy) with dedup + case-insensitivity
• Pure buildPlanProposal() applies priority ordering (ship > migrate > deploy > refactor > fix > audit > implement > test)
• Checkpoint continuation takes precedence over keyword heuristic when the prior session is interrupted
• Skip paths explain why no plan was offered (short task + no signals, no complexity keywords)
• WorkingMemoryBrief gains planProposal: PlanProposal | null field
• 32 new tests in run_a4_plan_proposal_tests.ts

Backward-compat verified

9 suites green: mock-provider, mock-failure-modes, b2-mock-classifier, mid-turn-attend, tool-call-retrieval, m2-tool-result-autowrite, user-operating-rules, compliance-task-relevance, file-change-recall.