memento

name	Memento
description	Activate on **EVERY SESSION**. Maintain a per-repo `.memento/` directory as an agent-owned, high-signal context scratchpad. **Always consult** `.memento` at the start of work. **Only update** `.memento` when the insight is high-signal, repo-specific, and likely to matter again. This is not documentation. It is a curated set of durable, project-shaping learnings from user steering, reversals, mistakes, and discoveries.
metadata	{"author":"Denis Tsai","version":"1.1.0","date":"2026-02-12T00:00:00.000Z","scope":"per-repository","persistence":"required"}

Memento: Durable Project Context (Curated)

You maintain a per-repo .memento/ directory that captures durable, high-signal context: architecture constraints, invariants, non-obvious workflows, gotchas, and “how this repo really works”.

Consult Memento at the start of every task.
Update Memento only when it clears the Signal Gate (below).

Retrieval (Mandatory)

Invariants:

• Never write to .memento without first scanning it for related context.
• Never store secrets, credentials, tokens, or personally identifiable information.

Before starting any task, you MUST:

1. Extract task-specific keywords (symbols, systems, subsystems, error strings).
2. Search across .memento/.
3. Apply relevant constraints, patterns, and prior decisions silently.

If .memento/ does not exist yet, create it.

Recommended structure:

.memento/
├── overview.md          # “How this repo works” (invariants, architecture, ethos)
├── workflows.md         # Non-obvious repo workflows (deploy, release, local dev)
├── gotchas.md           # Sharp edges + fixes (repo-specific, recurring)
├── decisions.md         # Decisions + rationale + alternatives considered
└── preferences.md       # User steering for this repo/workstream

The Signal Gate (Updates are Conditional)

Do NOT update .memento unless ALL of these are true:

1. Repo-specific: tied to this codebase, its tooling, its architecture, or its ops.
2. Non-obvious: not generic language/tool knowledge or something easily googled.
3. Durable: likely relevant again in ≥2 weeks or across sessions.
4. Actionable: can be written as a rule, invariant, or “if X then do Y”.

Hard exclusions (do not record):

• Generic Programming language style tips, linting “silencing” patterns, etc.
• Routine commands for formatting, compiling, build warnings and errors.
• Anything you could paste into a general best-practices blog post.

Allowed examples (good candidates):

• “This repo pins nightly because macro X breaks on stable; do not upgrade without Y.”
• “CI uses feature flags A/B; local tests must mirror with ENV var Z.”
• “DB migrations must run in this order because of lock contention in prod.”
• “This service expects ids to be canonicalized in layer N, not at the edge.”

Update Triggers (When the Gate Passes)

Update .memento when a high-signal event occurs and passes the Signal Gate:

• You hit a recurring error and learn the real cause in this repo.
• The user corrects an assumption about architecture/intent.
• You discover a hidden invariant (ordering, state model, naming, version pinning).
• A workflow differs from “standard” in a meaningful way (deploy, build, test, release).
• You reverse a decision after learning constraints (record why).

Writing Rules (Keep It Sharp)

When you do write:

• Prefer rules/invariants over narratives.
• Include the why in 1 line, and the do this instead in 1 line.
• Date entries only if it helps track drift.
• If something becomes repeated, promote it into overview.md or workflows.md.

Example entry format:

### Invariant: <short name>
- Context: <where this bites>
- Rule: <what to do / not do>
- Why: <one-line reason>
- Symptoms: <error strings or failure modes>

Maintenance (Always Curated)

• Merge duplicates into one rule.
• Delete stale notes aggressively.
• Keep .memento/ small: high-signal only (target: <200 lines total across files).
• If you find yourself logging “tips”, you’re drifting—stop and re-apply the Signal Gate.