## Philosophy

ADRs created with this skill are **executable specifications for coding agents**. A human approves the decision; an agent implements it. The ADR must contain everything the agent needs to write correct code without asking follow-up questions.

This means:

- Constraints must be explicit and measurable, not vibes
- Decisions must be specific enough to act on ("use PostgreSQL 16 with pgvector" not "use a database")
- Consequences must map to concrete follow-up tasks
- Non-goals must be stated to prevent scope creep
- The ADR must be self-contained — no tribal knowledge assumptions
- **The ADR must include an implementation plan** — which files to touch, which patterns to follow, which tests to write, and how to verify the decision was implemented correctly

## When to Write an ADR

Write an ADR when a decision:

- **Changes how the system is built or operated** (new dependency, architecture pattern, infrastructure choice, API design)
- **Is hard to reverse** once code is written against it
- **Affects other people or agents** who will work in this codebase later
- **Has real alternatives** that were considered and rejected

Do NOT write an ADR for:

- Routine implementation choices within an established pattern
- Bug fixes or typo corrections
- Decisions already captured in an existing ADR (update it instead)
- Style preferences already covered by linters or formatters

When in doubt: if a future agent working in this codebase would benefit from knowing _why_ this choice was made, write the ADR.

### Proactive ADR Triggers (For Agents)

If you are an agent coding in a repo and you encounter any of these situations, **stop and propose an ADR** before continuing:

- You are about to introduce a new dependency that doesn't already exist in the project
- You are about to create a new architectural pattern (new way of handling errors, new data access layer, new API convention) that other code will need to follow
- You are about to make a choice between two or more real alternatives and the tradeoffs are non-obvious
- You are about to change something that contradicts an existing accepted ADR
- You realize you're writing a long code comment explaining "why" — that reasoning belongs in an ADR

**How to propose**: Tell the human what decision you've hit, why it matters, and ask if they want to capture it as an ADR. If yes, run the full four-phase workflow. If no, note the decision in a code comment and move on.

## Creating an ADR: Four-Phase Workflow

Every ADR goes through four phases. Do not skip phases.

### Phase 0: Scan the Codebase

Before asking any questions, gather context from the repo:

1. **Find existing ADRs.** Check `contributing/decisions/`, `docs/decisions/`, `adr/`, `docs/adr/`, `decisions/` for existing records. Read them. Note:

   - Existing conventions (directory, naming, template style)
   - Decisions that relate to or constrain the current one
   - Any ADRs this new decision might supersede

2. **Check the tech stack.** Read `package.json`, `go.mod`, `requirements.txt`, `Cargo.toml`, or equivalent. Note relevant dependencies and versions.

3. **Find related code patterns.** If the decision involves a specific area (e.g., "how we handle auth"), scan for existing implementations. Identify the specific files, directories, and patterns that will be affected by the decision.

4. **Check for ADR references in code.** Look for ADR references in comments and docs (see "Code ↔ ADR Linking" below). This reveals which existing decisions govern which parts of the codebase.

5. **Note what you found.** Carry this context into Phase 1 — it will sharpen your questions and prevent the ADR from contradicting existing decisions.

### Phase 1: Capture Intent (Socratic)

Interview the human to understand the decision space. Ask questions **one at a time**, building on previous answers. Do not dump a list of questions.

**Core questions** (ask in roughly this order, skip what's already clear from context or Phase 0):

1. **What are you deciding?** — Get a short, specific title. Push for a verb phrase ("Choose X", "Adopt Y", "Replace Z with W").
2. **Why now?** — What broke, what's changing, or what will break if you do nothing? This is the trigger.
3. **What constraints exist?** — Tech stack, timeline, budget, team size, existing code, compliance. Be concrete. Reference what you found in Phase 0 ("I see you're already using X — does that constrain this?").
4. **What does success look like?** — Measurable outcomes. Push past "it works" to specifics (latency, throughput, DX, maintenance burden).
5. **What options have you considered?** — At least two. For each: what's the core tradeoff? If they only have one option, help them articulate why alternatives were rejected.
6. **What's your current lean?** — Capture gut intuition early. Often reveals unstated priorities.
7. **Who needs to know or approve?** — Decision-makers, consulted experts, informed stakeholders.
8. **What would an agent need to implement this?** — Which files/directories are affected? What existing patterns should it follow? What should it avoid? What tests would prove it's working? This directly feeds the Implementation Plan.

**When to stop**: You have enough when you can fill every section of the ADR — including the Implementation Plan — without making things up.

**Intent Summary Gate**: Before moving to Phase 2, present a structured summary of what you captured and ask the human to confirm or correct it.

### Phase 2: Draft the ADR

1. Choose the ADR directory (use existing or create `docs/decisions/`).
2. Choose a filename strategy (date prefix or slug-only, matching existing convention).
3. Choose a template (simple or MADR).
4. Fill every section from the confirmed intent summary.
5. Write the Implementation Plan — tells the next agent exactly what to do.
6. Write Verification criteria as checkboxes.
7. Generate the file (prefer running `scripts/new_adr.js`).

### Phase 3: Review Against Checklist

After drafting, review the ADR against the agent-readiness checklist in `references/review-checklist.md`. Present a summary of passes and gaps, not a raw checklist dump.

## Consulting ADRs (Read Workflow)

Agents should read existing ADRs **before implementing changes** in a codebase that has them.

1. Find the ADR directory.
2. Scan titles and statuses.
3. Read relevant ADRs fully (context, decision, consequences, non-goals, AND Implementation Plan).
4. Respect accepted decisions.
5. Follow the Implementation Plan patterns.
6. Reference ADRs in your work via code comments.

## Code ↔ ADR Linking

Add ADR path comments at entry points of code governed by a decision:

```typescript
// ADR: Using better-sqlite3 for test database
// See: docs/decisions/2025-06-15-use-sqlite-for-test-database.md
import Database from 'better-sqlite3';
```

## Resources

- `scripts/new_adr.js` — create a new ADR file from a template
- `scripts/set_adr_status.js` — update an ADR status in-place
- `scripts/bootstrap_adr.js` — create ADR dir and initial decision
- `references/review-checklist.md` — agent-readiness checklist
- `references/adr-conventions.md` — directory, filename, status, lifecycle conventions
- `assets/templates/adr-simple.md` — lean template
- `assets/templates/adr-madr.md` — MADR 4.0 template

---

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