Mnemos — Task-Scoped Memory Lifecycle

What It Does

Mnemos prevents lossy context compaction from destroying the structured knowledge you need most. It treats your working memory as a typed graph (MnemoGraph) where different types of knowledge have different eviction policies:

• GoalNodes and ConstraintNodes are NEVER evicted — they survive all compaction
• ResultNodes are compressed (summary kept) before eviction
• ContextNodes are evictable when their activation weight drops
• CheckpointNodes persist to disk for session resume

Fatigue Model

Mnemos monitors 4 dimensions of "agent fatigue" — all passively observed from hook data, no manual input needed:

| Dimension | Weight | Signal Source | What It Measures | |-----------|--------|--------------|-----------------| | Token utilization | 0.40 | Statusline JSON | How full the context window is | | Scope scatter | 0.25 | PreToolUse file paths | How many directories the agent is bouncing between | | Re-read ratio | 0.20 | PreToolUse Read calls | How often the agent re-reads files it already read (context loss) | | Error density | 0.15 | PostToolUse outcomes | What fraction of tool calls are failing (agent struggling) |

Fatigue states and actions:

| State | Score | Action | |-------|-------|--------| | FLOW | 0.0–0.4 | Normal operation | | COMPRESS | 0.4–0.6 | Micro-consolidation runs (compress 3 ResultNodes, evict 1 cold ContextNode) | | PRE-SLEEP | 0.6–0.75 | Checkpoint written, consolidation runs | | REM | 0.75–0.9 | Emergency checkpoint, consider wrapping up | | EMERGENCY | 0.9+ | Checkpoint written, hand off immediately |

How To Use

Automatic (hooks handle everything):

1. Statusline writes fatigue.json on every API call
2. PreToolUse hook reads fatigue before every edit, auto-checkpoints at 0.60+
3. PreCompact hook writes emergency checkpoint, compaction marker, and tells summarizer what to preserve
4. SessionStart "compact" fires immediately after compaction, re-injects full checkpoint (primary restore)
5. SessionStart "startup|resume" loads last checkpoint on new/resumed sessions
6. PreToolUse fallback (no matcher) detects compaction marker if SessionStart didn't fire
7. Stop hook writes final checkpoint for next session

Post-Compaction Recovery (Three-Layer Defense):

When Claude Code compacts the context (~83% full), Mnemos uses three layers:

• Layer 1 (PreCompact): Outputs strong preservation instructions with inline checkpoint content for the summarizer. Writes .mnemos/just-compacted marker.
• Layer 2 (SessionStart "compact"): PRIMARY re-injection. Fires immediately when Claude resumes after compaction — before any agent action. Consumes the marker and injects the full checkpoint into the fresh context. This is the recommended approach per the RFC (Wake State Reconstruction).
• Layer 3 (PreToolUse fallback): If SessionStart doesn't fire (older versions, edge cases), the first tool call triggers mnemos-post-compact-inject.sh which detects the marker and injects. Safety net only.

The result: after compaction, you'll see a "CONTEXT RESTORED AFTER COMPACTION" block with your goal, constraints, what you were working on, and progress. Resume from there.

Manual CLI:

bash
mnemos init                    # Initialize .mnemos/
mnemos status                  # Show node counts + fatigue
mnemos fatigue                 # Detailed fatigue breakdown
mnemos checkpoint --force      # Write checkpoint now
mnemos resume                  # Output checkpoint for context
mnemos consolidate             # Run micro-consolidation
mnemos nodes --type goal       # List active GoalNodes
mnemos add goal "Build auth"   # Add a GoalNode
mnemos bridge-icpg             # Import iCPG ReasonNodes
mnemos ingest-claude --all     # Ingest Claude Code transcripts (see below)
mnemos haze --recent 10        # Show per-session haziness scores

Claude Transcript Ingestion & Haziness

Mnemos can ingest Claude Code session transcripts (the per-session JSONL under ~/.claude/projects/) and score each session's haziness — a measure of how much the agent struggled. The Stop hook does this automatically on session exit; it is also available manually.

What's stored: only structural fields (roles, tool names, file paths, error flags, timestamps) plus a redacted, 200-char preview of each turn. Full content is never persisted, and secrets (API keys, tokens, PEM blocks, JWTs, credentials) are redacted before anything touches disk.

Haziness is a weighted score over five dimensions, each in [0,1]:

| Dimension | Weight | What it measures | |-----------|--------|------------------| | correction_density | 0.30 | User corrections per eligible user turn | | redo_ratio | 0.25 | Edits re-touched after an error | | first_try_error_rate | 0.20 | Edits followed by errors within 3 turns | | orphan_tool_use_rate | 0.15 | Tool calls with no matching result | | backtrack_norm | 0.10 | git revert/reset --hard/restore calls |

The composite maps to a band: clear < 0.25 ≤ cloudy < 0.50 ≤ hazy < 0.75 ≤ lost.

bash
mnemos ingest-claude --all              # ingest every transcript + score
mnemos ingest-claude --session <id>     # one session by id
mnemos ingest-claude --transcript <f>   # a specific JSONL file
mnemos haze --recent 10                 # table of recent sessions
mnemos haze --session <id>              # per-dimension breakdown

Ingestion is idempotent (resumes via last_line_offset). Opt out per project with touch .mnemos/claude-log.disabled.

Agent Instructions

When working on a task:

1. Create a GoalNode at the start: mnemos add goal "what you're trying to achieve" --task-id session-1
2. Add ConstraintNodes for invariants: mnemos add constraint "API backward compatibility" --scope src/api/
3. Check fatigue before long operations: mnemos fatigue
4. Checkpoint at sub-goal boundaries: mnemos checkpoint
5. On session resume: the SessionStart hook automatically loads your checkpoint

iCPG Integration

Mnemos bridges with iCPG (Intent-Augmented Code Property Graph):

• mnemos bridge-icpg imports active ReasonNodes as GoalNodes
• Postconditions/invariants become ConstraintNodes
• Checkpoint includes iCPG state (active intent, unresolved drift)

Storage

Everything lives in .mnemos/ (gitignored):

• mnemo.db — SQLite MnemoGraph
• fatigue.json — Live token metrics (updated per API call by statusline)
• signals.jsonl — Behavioral signal log (appended by PreToolUse + PostToolUse hooks)
• checkpoint-latest.json — Most recent checkpoint
• checkpoints/ — Archived checkpoints