feat(llm): Add Vibe CLI integration initiative (T-497, D-105)

- Add D-105: Support Vibe CLI as opt-in alternative to Claude Code CLI
- Add T-497 initiative with 6 children:
  - T-498: Adapt StreamJsonProcess + session management
  - T-500: Update config system for per-repo LLM selection
  - T-501: LLMDriver abstraction + per-repo config schema
  - T-502: Verify Vibe CLI permission + tool behavior
  - T-503: Hybrid LLM test suite + regression checks
  - T-504: pql improvements for hybrid agent workflow

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

governance/decisions/llm.md

@@ -0,0 +1,84 @@
+# LLM Integration Decisions
+
+Decisions around Large Language Model integration, driver abstraction, and
+multi-LLM support in clide.
+
+---
+
+### D-105: Support Vibe CLI as opt-in alternative to Claude Code CLI
+
+- **Date:** 2026-06-28
+- **Status:** confirmed
+- **Supersedes:** None
+- **See Also:** online-mistral-analysis.md, D-6 (CLI/UI parity), D-56 (single process)
+- **Raised by:** Mistral Vibe evaluation
+
+#### Decision
+
+**We will support Vibe CLI as an opt-in alternative to Claude Code CLI in clide.**
+
+Vibe CLI provides **stdio protocol, permission prompts, session persistence,
+and MCP support** — making it a **~95% feature-parity drop-in replacement** for
+Claude Code CLI. This enables users to select their preferred LLM driver on a
+per-repo basis while maintaining full backward compatibility with the
+existing Claude flow.
+
+#### Context
+
+Claude Code CLI is clide's current and primary LLM. User requested the
+ability to switch to Mistral's offerings. Two paths were considered:
+
+1. **Raw Mistral API** — Requires reimplementing stdio protocol, permission
+   prompts, session management. Effort: 3-4 weeks. Parity: ~70%.
+
+2. **Vibe CLI** — Mistral's open-source CLI that **natively supports** stdio
+   protocol, permission prompts (`can_use_tool`), session persistence
+   (`--resume`), MCP servers, and JSONL transcripts. Effort: 1-2 weeks.
+   Parity: ~95%.
+
+The analysis in `online-mistral-analysis.md` confirms Vibe CLI is the
+**production-ready path**.
+
+#### Architectural Choice
+
+**Direct Vibe CLI Integration (Option 1 from analysis):**
+- Replace `claude` with `vibe` in clide's spawn logic
+- Adapt `StreamJsonProcess` and `TranscriptReader` for minor JSONL differences
+- Update `ClaudeConfig` to watch `.vibe/` instead of `.claude/`
+- Reuse clide's existing MCP broker for team orchestration
+
+**Fallback (Option 2):** Thin wrapper to normalize Vibe CLI output to match
+Claude's stream-json exactly. Only if protocol differences prove significant
+during testing.
+
+#### Implementation Constraints
+
+- **Claude remains primary** — Vibe CLI is opt-in; default driver stays `claude`
+- **Per-repo setting** — `llm.driver` in `.clide/config.yaml`, similar to multi-
+  Claude-account mechanism
+- **Zero regression** — All existing Claude functionality preserved
+- **Minimal abstraction** — Leverage Vibe CLI's native parity; avoid thick
+  conversion layers
+
+#### Success Criteria
+
+- User can select `llm.driver: claude | mistral` in per-repo config
+- Vibe CLI sessions work end-to-end: streaming, permissions, tools, MCP, session resume
+- `make test` passes with both drivers
+- No performance regression in Claude flow
+- Migration effort: 1-2 weeks
+
+#### Consequences
+
+**Positive:**
+- Users can choose their preferred LLM
+- Local inference support (offline/private use cases)
+- Minimal code changes (~1-2 weeks)
+- Full feature parity maintained
+
+**Negative:**
+- Additional binary dependency (Vibe CLI)
+- Maintenance burden for two drivers (mitigated by abstraction)
+- Testing matrix doubles (mitigated by CI feature flags)
+
+---