Session Hooks — Trace Skill Skill

Session Hooks — Trace Skill

When to Use

Activate this skill when:

A new coding session starts (user opens Claude Code, starts work)
A coding session ends (user is wrapping up, about to close)
User asks about "session hooks", "memory hooks", or "auto-load memory"
User wants to configure automatic memory loading/saving behavior

Overview

Session hooks are the automated entry and exit points for Trace's memory operating layer. They ensure that:

On session start: The @tracer agent is invoked, presents the memory overview, and asks the user which layers to load before work begins
On session end: The @tracer agent auto-saves the session to user memory (no prompt), then asks the user if team memory should be updated too

Installing Hooks (User Must Explicitly Ask)

Hooks are opt-in only. When the user asks to set up trace hooks, install them into the project's .claude/settings.json (never system-level).

Option 1: Run the install script

bash <path-to-code-guardian>/infynon-trace/hooks/install.sh <project-dir>

This creates or merges hooks into <project-dir>/.claude/settings.json.

Option 2: Write settings.json directly

Create .claude/settings.json in the project root:

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "startup|resume",
        "hooks": [
          {
            "type": "command",
            "command": "echo '=== INFYNON TRACE: MEMORY OVERVIEW ===' && infynon trace retrieve --layer canonical --format markdown 2>/dev/null || echo '[trace] Not initialized. Run: infynon trace init' && echo '' && echo '--- Team Memory Index ---' && infynon trace retrieve --layer team --format markdown --limit 5 2>/dev/null || echo '(no team notes)' && echo '' && echo '--- User Memory Index ---' && infynon trace retrieve --layer user --format markdown --limit 5 2>/dev/null || echo '(no user notes)' && echo '' && echo '[TRACE-HOOK] Invoke @tracer agent. Ask the user which memory layers to load before proceeding with the session.'",
            "timeout": 20
          }
        ]
      }
    ],
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "INPUT=$(cat); if [ \"$(echo \"$INPUT\" | jq -r '.stop_hook_active // false')\" = \"true\" ]; then exit 0; fi; echo '[TRACE-HOOK] Task complete. Invoke @tracer agent to: (1) Auto-save session observations to user memory using infynon trace note add --layer user --tags session-output,auto-saved — no prompt needed. (2) Run infynon trace compact. (3) Ask user if highlights should also be saved to team memory.'",
            "timeout": 5
          }
        ]
      }
    ]
  }
}

What the hooks do

SessionStart: Runs infynon trace retrieve for all layers, injects the memory overview into Claude's context, and instructs Claude to invoke @tracer to ask the user which layers to load.
Stop: Checks stop_hook_active to prevent infinite loops. When work is complete, instructs @tracer to auto-save to user memory (no prompt) and ask about team memory.

Important

Hooks go in the project .claude/settings.json, not ~/.claude/settings.json
If .claude/settings.json already exists, the install script merges (requires jq)
The user must explicitly ask to install hooks — never auto-install
To remove hooks, delete the trace entries from .claude/settings.json

Session Start Hook

Flow

Session Start
    │
    ├── 1. Load canonical memory (always)
    │       infynon trace retrieve --layer canonical --format markdown
    │
    ├── 2. Ask user: "Load team memory?"
    │       ├── Yes → infynon trace retrieve --layer team --format markdown
    │       └── No  → skip
    │
    ├── 3. (Optional) Load user memory
    │       infynon trace retrieve --layer user --author <current-user> --format markdown
    │
    └── 4. Pull from remote if configured
            infynon trace sync --direction pull

Implementation

Step 1: Load canonical memory (non-negotiable)

Canonical memory contains architecture decisions, API contracts, and security constraints. The agent must always know these before making changes.

infynon trace retrieve --layer canonical --format markdown

Review the output. These are the ground rules for this codebase.

Step 2: Ask about team memory

Team memory contains active caveats, handoffs, and working knowledge. It's useful but can be noisy.

Ask the user: "Do you want to load team memory for this session?"

If yes:

infynon trace retrieve --layer team --format markdown

If the user says no, that's fine — team memory is optional at session start.

Step 3: Optionally load user memory

If the user has personal notes from a previous session:

infynon trace retrieve --layer user --author <username> --format markdown

Step 4: Pull from remote

If a remote backend is configured, sync to get the latest notes:

infynon trace sync --direction pull

Session End Hook

Flow

Session End
    │
    ├── 1. Ask user: "Any observations to save?"
    │       ├── Yes → Create team/user notes
    │       └── No  → skip
    │
    ├── 2. Mark session-scoped notes as stale
    │       infynon trace note update <id> --status stale
    │
    ├── 3. Flag promotion candidates
    │       Any team note reused 3+ times without contradiction
    │
    ├── 4. Compact stale and session notes
    │       infynon trace compact
    │
    ├── 5. Push to remote if configured
    │       infynon trace sync --direction push
    │
    └── 6. NEVER auto-update canonical memory

Implementation

Step 1: Capture new observations

Ask the user if they learned anything worth saving:

"Did you discover anything during this session worth noting? (Architecture changes, caveats, handoff notes, bugs found)"

If yes, create notes in the appropriate layer:

# Team observation
infynon trace note add session-obs-<topic> \
  --title "<What was learned>" \
  --body "<Details and context>" \
  --layer team \
  --scope <appropriate-scope> \
  --tags session-output

# Personal note
infynon trace note add user-obs-<topic> \
  --title "<Personal observation>" \
  --body "<Details>" \
  --layer user \
  --author <username>

Step 2: Update stale notes

If any notes loaded at session start are now outdated:

infynon trace note update <id> --status stale

Step 3: Flag promotion candidates

If a team note was referenced multiple times this session and remains accurate:

infynon trace note update <id> --tags promote,canonical-candidate

Step 4: Compact

Clean up session-scoped and stale notes:

infynon trace compact

Step 5: Push to remote

infynon trace sync --direction push

Step 6: Never auto-update canonical

Even if the agent discovered something important, canonical updates require human review. At most, flag it:

infynon trace note add promote-<topic> \
  --title "Promote candidate: <topic>" \
  --body "Discovered during session. Needs validation before canonical promotion." \
  --layer team \
  --tags promote,needs-review

Hook Configuration

Reference: settings.json (full config)

The canonical hook configuration — same as Option 2 above, kept here for reference:

{
  "hooks": {
    "SessionStart": [
      {
        "matcher": "startup|resume",
        "hooks": [
          {
            "type": "command",
            "command": "echo '=== INFYNON TRACE: MEMORY OVERVIEW ===' && infynon trace retrieve --layer canonical --format markdown 2>/dev/null || echo '[trace] Not initialized. Run: infynon trace init' && echo '' && echo '--- Team Memory Index ---' && infynon trace retrieve --layer team --format markdown --limit 5 2>/dev/null || echo '(no team notes)' && echo '' && echo '--- User Memory Index ---' && infynon trace retrieve --layer user --format markdown --limit 5 2>/dev/null || echo '(no user notes)' && echo '' && echo '[TRACE-HOOK] Invoke @tracer agent. Ask the user which memory layers to load before proceeding.'",
            "timeout": 20
          }
        ]
      }
    ],
    "Stop": [
      {
        "hooks": [
          {
            "type": "command",
            "command": "INPUT=$(cat); if [ \"$(echo \"$INPUT\" | jq -r '.stop_hook_active // false')\" = \"true\" ]; then exit 0; fi; echo '[TRACE-HOOK] Task complete. Invoke @tracer agent to: (1) Auto-save session to user memory using infynon trace note add --layer user --tags session-output,auto-saved — no prompt needed. (2) Run infynon trace compact. (3) Ask user if highlights should also be saved to team memory.'",
            "timeout": 5
          }
        ]
      }
    ]
  }
}

Manual Invocation (no hooks installed)

If hooks are not configured, the agent should:

At session start — be explicitly invoked (@tracer) and run the session start workflow
When the user says "done", "wrapping up", "end session" — run the session end workflow manually

Rules

Canonical memory is always loaded — no exceptions, no user opt-out for this layer
Session start: ask before loading team/user — present overview, wait for user choice
Session end: auto-save user memory — always, no prompt required
Session end: ask before team memory — opt-in only
NEVER write canonical at session end — flag candidates only
Compaction always runs at end — keeps storage clean
Stop hook checks stop_hook_active — prevents infinite loops
Sync direction matters — pull at start, push at end
If no backend configured — use local file storage, skip sync steps

Tips

If the session is short (quick fix), skip the full hook workflow
If the user is investigating a bug, load team notes tagged with the affected module
If the user is doing a code review, load PR-scoped notes for that PR
Tag session-output notes so they can be easily found and promoted later
Don't over-save — only create notes for things that would be useful in a future session

Agent Skills: Session Hooks — Trace Skill

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