docs(05): capture phase context

.planning/phases/05-hindsight-memory-provider/05-CONTEXT.md

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+# Phase 5: Hindsight Memory Provider - Context
+
+**Gathered:** 2026-06-14
+**Status:** Ready for planning
+
+<domain>
+## Phase Boundary
+
+Enable Hindsight as the cross-session memory provider for ngn-agent. Replace the built-in MEMORY.md/USER.md with Hindsight's entity-aware knowledge graph memory for persistent recall across sessions. Pure configuration change — no code, no new infrastructure, no Docker image changes.
+
+**In scope:** Hindsight memory provider activation, configuration tuning for latency sensitivity, integration with existing Hermes agent loop
+
+**Out of scope:** Migration of existing MEMORY.md/USER.md data, custom memory provider implementation, multi-provider setup, session lifecycle features (Phase 7), cron reporting (Phase 8)
+</domain>
+
+<decisions>
+## Implementation Decisions
+
+### Hindsight Mode
+- **D-01:** Use **local embedded** mode — Hermes spins up a local PostgreSQL daemon. No external data send. Use existing OpenRouter API key (`OPENROUTER_API_KEY` in `~/.hermes/.env`) for LLM extraction via `HINDSIGHT_LLM_API_KEY`.
+  - Config: `mode: local_embedded` in `~/.hermes/hindsight/config.json`
+  - Env: `HINDSIGHT_LLM_API_KEY=sk-or-v1-...` (same as existing OpenRouter key)
+  - Provider: `openrouter` with model per-provider default
+
+### Memory Integration
+- **D-02:** Use **default (hybrid)** mode — auto-inject relevant memories before each turn + expose all 3 hindsight tools (hindsight_retain, hindsight_recall, hindsight_reflect) to the agent
+  - Config: `memory_mode: hybrid` (default)
+
+### Migration
+- **D-03:** No migration from built-in memory. MEMORY.md/USER.md will continue to work as a fallback in parallel — built-in memory writes via `memory` tool still work alongside hindsight. Hindsight does not sync with built-in memory. This is acceptable — hindsight will build its own knowledge graph from new sessions.
+
+### Recall Settings (latency-optimized)
+- **D-04:** `recall_budget: low` — fastest retrieval, minimal latency overhead per turn
+- **D-05:** `recall_prefetch_method: recall` — raw fact search (no LLM synthesis in the hot path)
+- **D-06:** `auto_recall: true` — still auto-inject context before each turn
+- **D-07:** `recall_types: observation` — default (observations only, denser per token)
+
+### Retain Settings (latency-optimized)
+- **D-08:** `retain_async: true` — processing happens in background, never blocks agent loop
+- **D-09:** `retain_every_n_turns: 5` — extract memories every 5 turns instead of every turn, ~80% overhead reduction
+- **D-10:** `auto_retain: true` — automatic retention active
+
+### the agent's Discretion
+- **Bank configuration** (`bank_id`, `bank_mission`, `bank_retain_mission`): Use defaults (`bank_id: hermes`, no missions). Planner can recommend tuning if needed.
+- **Daemon startup logs and runtime monitoring**: Standard Hermes daemon management applies (`~/.hermes/logs/hindsight-embed.log`, `~/.hindsight/profiles/`).
+
+</decisions>
+
+<canonical_refs>
+## Canonical References
+
+**Downstream agents MUST read these before planning or implementing.**
+
+### Hindsight Plugin
+- `~/.hermes/hermes-agent/plugins/memory/hindsight/README.md` — Full Hindsight configuration reference with all options, environment variables, and modes
+- `~/.hermes/hermes-agent/plugins/memory/hindsight/plugin.yaml` — Plugin metadata, pip dependencies (`hindsight-client>=0.4.22`), hooks
+
+### Hermes Memory System
+- `~/.hermes/hermes-agent/plugins/memory/__init__.py` §12 — "Only ONE provider can be active at a time" constraint (`memory.provider` config)
+- `~/.hermes/hermes-agent/agent/memory_manager.py` lines 342-354 — Provider conflict logic (second external provider silently rejected)
+
+### Project Documents
+- `.planning/REQUIREMENTS.md` §MEM-01 — Requirement definition with verification criteria
+- `.planning/ROADMAP.md` §Phase 5 — Phase goal and success criteria
+- `.planning/PROJECT.md` — Core value, constraints, existing Hermes config
+- `.planning/research/SUMMARY.md` §Phase 1 — Research findings on hindsight setup, pitfalls, and recommendations
+- `.planning/research/PITFALLS.md` §Memory Provider Conflict — Critical pitfall on setting multiple providers
+
+### Existing Configuration
+- `~/.hermes/config.yaml` §memory — Current memory config (provider field to change, existing settings to preserve)
+- `~/.hermes/.env` — Existing environment variables (OpenRouter key to reuse for HINDSIGHT_LLM_API_KEY)
+</canonical_refs>
+
+<code_context>
+## Existing Code Insights
+
+### Reusable Assets
+- **Hindsight plugin** (`plugins/memory/hindsight/`): Already bundled in Hermes v0.16.0, production-ready, requires only config change + pip install
+- **Built-in memory** (MEMORY.md/USER.md): Continues working in parallel as fallback — no code changes needed
+
+### Established Patterns
+- **Single provider constraint** (`plugins/memory/__init__.py:12`): Hermes enforces only one external memory provider. Setting `memory.provider: hindsight` replaces built-in as the active external provider
+- **Async retain** (`memory_provider.py:115-131`): Memory retains are async and non-blocking by default — confirms our latency-optimized approach is supported upstream
+
+### Integration Points
+- `~/.hermes/config.yaml` §`memory.provider` — Change from default to `hindsight`
+- `~/.hermes/.env` — Add `HINDSIGHT_LLM_API_KEY` env var (reuse existing OpenRouter key)
+- `~/.hermes/hindsight/config.json` — Create with our latency-optimized settings (auto-generated by `hermes memory setup`, then tuned)
+</code_context>
+
+<specifics>
+## Specific Ideas
+
+No specific requirements — open to standard approaches. Follow the Hindsight plugin README setup instructions, then apply the latency-optimized config overrides from decisions D-04 through D-10.
+</specifics>
+
+<deferred>
+## Deferred Ideas
+
+None — discussion stayed within phase scope.
+</deferred>
+
+---
+
+*Phase: 5-Hindsight Memory Provider*
+*Context gathered: 2026-06-14*