Phase 5c: core/loop

[cjimti]

Part of #1 and #6 (project bootstrap, v0.1, phase 5 split). Blocked by 5a and 5b.

Deliverables

core/loop/

• Config struct (Provider, MCP, Router, Approver, Logger, MaxSteps).
• Run(ctx, cfg, sess, userMessage) (<-chan event.Event, error).
• Behavior:
  1. Append user message to session.
  2. Optional Router.Narrow for the turn.
  3. Stream from Provider with narrowed tools.
  4. Forward TextDelta; on ToolCallRequest → Approver.Approve → MCP dispatch → append result to session → re-stream.
  5. Forward Finish / Error and exit.
  6. Enforce MaxSteps cap.
• Recover from panics in tool handlers → event.Error; do not recover panics from Provider/core.
• Structured logging via slog (helper at core/log/ if needed).

Tests

• Loop tests using provider.FakeProvider — no live model, no live MCP.
• Cover: text-only turn; tool-call turn; multi-step tool chain; MaxSteps enforcement; approval denied; approval allow-all-for-session; provider error mid-stream; mcp error during dispatch; context cancellation.
• -race clean, -shuffle=on clean.
• Coverage contributes to the >80% core/... gate.

Out of scope

• SQL safety middleware (v0.2)
• OpenTelemetry tracing (v0.3)

Branch

feat/bootstrap-loop (off main after 5b merges)

Spec: §6.5, §11, §12 of the bootstrap spec in #1.