Plan Backlog

Plan Backlog Skill

Convert Linear Backlog issues into a structured TDD implementation plan written to PLANS.md.

Overview

This skill takes one or more Linear issues from the Backlog state and produces a detailed, step-by-step TDD implementation plan. The plan is written to PLANS.md at the project root. After planning, the Linear issues are moved to the "Todo" state.

This skill creates plans. It does NOT implement them.

Workflow

Phase 1: Pre-Flight Checks

1.1 Git Pre-Flight

Before doing anything, verify the git state:

git status
git branch --show-current

Requirements:

• Must be on main branch
• Working tree must be clean (no uncommitted changes)

If either check fails, STOP and report the issue to the user. Do not proceed.

1.2 PLANS.md Pre-Flight

Check if PLANS.md exists at the project root:

ls -la PLANS.md

Rules:

• If PLANS.md does not exist: OK, proceed.
• If PLANS.md exists and its status is COMPLETE: OK, proceed (it will be overwritten).
• If PLANS.md exists and its status is NOT COMPLETE: STOP. Tell the user there is an active plan that must be completed or removed first.

To check status, read the file and look for EITHER:

• **Status:** COMPLETE in the header (line 3), OR
• ## Status: COMPLETE anywhere in the file (appended by plan-review-implementation)

If either marker is found, the plan is complete.

1.3 Verify Linear MCP

Call mcp__linear__list_teams. If unavailable, STOP and tell the user: "Linear MCP is not connected. Run /mcp to reconnect, then re-run this skill."

Phase 2: Gather Context

2.1 Query Linear for Backlog Issues

Use the Linear MCP to find the requested issues.

First, discover the team name:

Read CLAUDE.md and look for LINEAR INTEGRATION section. Extract the team name from patterns like:

• "Team: 'ProjectName'"
• "Team: ProjectName"

If CLAUDE.md doesn't have a LINEAR INTEGRATION section, call mcp__linear__list_teams to discover the team name dynamically.

Store the discovered team name in a variable for use throughout the skill.

If user specified a specific issue (e.g., "PROJ-123"):

mcp__linear__get_issue(issueId: "PROJ-123")

Verify the issue exists and is in the "Backlog" state. If not in Backlog, warn the user but continue if they confirm.

If user specified a filter (e.g., "all Bug issues", "the auth issue"):

First, get the team's issue statuses and labels:

mcp__linear__list_issue_statuses(team: [discovered team name])
mcp__linear__list_issue_labels(team: [discovered team name])

Then query for Backlog issues:

mcp__linear__list_issues(team: [discovered team name], state: "Backlog", includeArchived: false)

Filter the results based on the user's criteria (label, title keywords, etc.).

If user said "plan all", "work on backlog", or provided no arguments:

mcp__linear__list_issues(team: [discovered team name], state: "Backlog", includeArchived: false)

Plan ALL returned Backlog issues. No confirmation needed — the triage phase (Phase 3) will filter out invalid ones.

2.2 Read CLAUDE.md

Read the project's CLAUDE.md file to understand:

• Project architecture and conventions
• Available MCP servers and their capabilities
• Testing patterns and preferences
• Code style and structure guidelines

Read CLAUDE.md

This is critical for generating plans that align with the project's patterns.

2.3 Explore the Codebase

Explore the codebase to understand existing patterns using dedicated tools (NOT Bash):

• Use Glob to discover project structure and find files by pattern
• Use Read for package config and build config files
• Use Grep to search for patterns: function names, class definitions, annotations

What to find:

• Existing components similar to what the issues require
• Test file patterns and conventions
• API route patterns
• Database/data patterns
• Shared utilities and hooks

2.4 Gather MCP Context

Based on what you learned from CLAUDE.md, identify which MCP servers are available. Common ones for this project:

• Linear MCP: Issue tracking, status updates
• Railway MCP: Deployment and infrastructure context

Query relevant MCPs to gather context that will inform the plan. For example:

• Check Railway for existing services and environment variables
• Check Linear for related issues or dependencies

2.5 Preserve Sentry References

When planning issues that contain Sentry references in their Linear description (look for **Sentry Issue:** sections), carry those Sentry issue URLs into the PLANS.md **Sentry Issues:** header field. This ensures the downstream plan-review-implementation skill can resolve them when the plan is complete.

Phase 3: Triage Issues

Before planning, assess whether each backlog issue is valid and actionable in the current project context. Issues from code audits may flag theoretical problems that don't apply.

3.1 Validate Each Issue

For each candidate issue, read the referenced code and ask:

1. Does the problem actually exist? Read the file/line cited in the issue. Is the code actually there? Does it behave as the issue claims?
2. Is it relevant to the project context? Consider:
   • Project status (DEVELOPMENT = no legacy data, no backward compatibility)
   • Single-user vs multi-user implications
   • Client-side vs server-side distinctions
   • Whether the "fix" is already the correct behavior
3. Is it a real risk or a theoretical concern? A single-user app behind auth doesn't need the same defenses as a public API.
4. Is it already addressed? Check if another issue or existing code already handles this.

3.2 Classify Issues

Place each issue in one of two categories:

3.3 Cancel Invalid Issues

For each invalid issue:

1. Add a comment explaining why the issue is being canceled:

mcp__linear__create_comment(issueId: "PROJ-xxx", body: "Canceled during triage: [reason]")

The reason should be specific, e.g.:

• "Project is in DEVELOPMENT status with no legacy data — plaintext token migration path is dead code."
• "console.error is the correct choice for client-side error boundaries — pino is server-only."
• "Single-user app behind auth — x-forwarded-for spoofing is not a real risk."

2. Move to Canceled state.

CRITICAL: Linear MCP same-type state bug. "Duplicate" and "Canceled" are both type: canceled in Linear. Passing state: "Canceled" by name silently no-ops if the issue is already in another canceled-type state. To reliably cancel issues, first fetch the team's statuses to get the Canceled state UUID:

mcp__linear__list_issue_statuses(team: [discovered team name])

Find the status with name: "Canceled" and use its id (UUID) in the update call:

mcp__linear__update_issue(id: "PROJ-xxx", state: "<canceled-state-uuid>")

Always use the UUID, never the name, for canceled-type state transitions.

3.4 Report Triage Results

Before proceeding, present the triage results to the user:

## Triage Results

**Valid (will be planned):**
- PROJ-123: [title] — [brief reason it's valid]
- PROJ-456: [title] — [brief reason it's valid]

**Canceled:**

| Issue | Title | Reason |
|-------|-------|--------|
| PROJ-789 | [title] | [specific reason it's invalid] |
| PROJ-012 | [title] | [specific reason it's invalid] |

Document canceled issues in the plan's Scope Boundaries → Out of Scope section with the cancellation reason.

If ALL issues are invalid, STOP — inform the user that no issues need planning.

If valid issues remain, proceed to Phase 4.

Phase 4: Generate the Plan

4.1 Analyze Requirements

For each issue being planned:

1. Read the issue title, description, and any comments
2. Identify acceptance criteria (explicit or implied)
3. Identify dependencies on other issues or existing code
4. Determine the scope of changes needed
5. Identify which files will be created or modified

4.2 Design the Implementation

For each issue:

1. Break down into small, testable tasks
2. Order tasks so each builds on the previous
3. Identify the TDD cycle for each task (test first, then implement)
4. Note any MCP tools that will be useful during implementation
5. Identify potential risks or questions

4.3 Write PLANS.md

Write the plan to PLANS.md at the project root using the structure template below.

4.4 Validate Plan Against CLAUDE.md

After writing the plan but before moving issues to Todo, re-read CLAUDE.md and cross-check each task for missing defensive specs:

Fix any violations found before proceeding. This step prevents the plan from introducing gaps that become bugs at implementation time.

4.5 Cross-Cutting Requirements Sweep

After writing all tasks, scan the entire plan for these patterns. If a pattern is detected in any task, verify the corresponding specification exists in that task's steps. If missing, add it before finalizing the plan.

PLANS.md Structure

Read references/plans-template.md for the complete template.

Source field: Backlog: PROJ-123, PROJ-456 (list the issue keys being planned)

Include: Context Gathered (Codebase Analysis + MCP Context + Triage Results), Tasks, Post-Implementation Checklist, Plan Summary. Omit: Investigation subsection.

Weave each issue's acceptance criteria into the relevant task steps — do not create a separate Issues section.

Task Writing Guidelines

When writing tasks in the plan:

1. Be specific: Name exact files, functions, and components.
2. Be ordered: Each task should build on the previous one. Never reference something that hasn't been created in an earlier task.
3. Be testable: Every task must have a clear test-first approach. Write the test assertion before the implementation.
4. Be small: Each task should be completable in 15-30 minutes. If it's bigger, break it down further.
5. Reference patterns: Point to existing code in the codebase that the implementer should follow.
6. Include file paths: Always specify the full file path for every file created or modified.
7. Include commands: Provide the exact terminal commands to run tests, linters, etc.
8. Note dependencies: If a task depends on a previous task, say so explicitly.
9. Specify defensive requirements: For each task, think about what can go wrong and include it in the TDD steps. Specifically:
   • Error paths: What exceptions can the code throw? Specify how they should be caught, logged, or propagated. Include error-path tests in the RED phase.
   • Edge cases: Empty data, null values, concurrent access, partial results. Include edge-case tests.
   • Timeouts: Any external call (network, IPC, third-party API) MUST specify a timeout value and what happens on timeout.
   • Permission/auth checks: Any operation that requires permissions must check them first and handle denial.
   • Cancellation: Async operations that can be triggered multiple times must specify cancellation of in-flight work.
   • State consistency: If an operation can fail mid-way, specify how the state is cleaned up or rolled back.
10. Cross-check CLAUDE.md constraints: Before including any dependency in a task, verify CLAUDE.md allows it. Verify layer boundaries are respected (e.g., domain layer stays pure). Verify all dependency additions follow the project's dependency management conventions. Verify logging follows the project's patterns.

TDD Pattern

Every implementation task MUST follow the Red-Green-Refactor cycle:

• RED: Write a failing test first. Specify what the test asserts and what error message is expected. Include at least one error-path or edge-case test for any task that touches external APIs, async operations, or state management.
• GREEN: Write the minimum code to make the test pass. Do not over-engineer.
• REFACTOR: Clean up the code while keeping tests green. Extract shared logic, improve naming, etc.

MCP Usage Guidelines

When planning, consider how MCPs will be used during implementation:

Linear MCP

• Move issues to "In Progress" when implementation starts
• Move issues to "Done" when implementation is complete
• Add comments to issues with progress updates if needed

Other MCPs

• Check existing services and their configuration
• Verify environment variables are set correctly
• Understand deployment pipeline for the project

Rules

1. PLANS.md is the single source of truth. All planning output goes into this file.
2. Never modify existing code. This skill only creates PLANS.md. It does not create or edit source files.
3. One plan at a time. If PLANS.md already has an active (non-COMPLETE) plan, do not overwrite it.
4. Always verify Linear state. Confirm issues are in Backlog before planning them.
5. Always read CLAUDE.md. The project configuration file contains critical context.
6. Always explore the codebase. Plans must reference real files and real patterns from the project.
7. Triage before planning. Validate every issue against the actual codebase. Cancel issues that don't apply to the current project context.
8. Use state UUID for Canceled. Never pass state: "Canceled" by name — use the UUID from list_issue_statuses. The Linear MCP silently no-ops same-type state transitions by name.
9. TDD is mandatory. Every task must follow the Red-Green-Refactor cycle.
10. Plans must be self-contained. An implementer should be able to follow the plan without needing to re-read the Linear issues.
11. Keep scope tight. Only plan what the issues ask for. Do not add nice-to-haves.
12. Plans describe WHAT and WHY, not HOW at the code level. Include: file paths, function names, behavioral specs, test assertions, patterns to follow (reference existing files by path), state transitions. Do NOT include: implementation code blocks, ready-to-paste TypeScript/TSX, full function bodies. The implementer (plan-implement workers) writes all code — your job is architecture and specification. Exception: short one-liners for surgical changes (e.g., "add if (!session.x) check after the existing !session.y check") are fine.
13. Move valid issues to Todo. After writing the plan, update the valid Linear issues to the "Todo" state.
14. Flag migration-relevant tasks. If a task changes a data schema, renames columns or fields, restructures stored data, changes identity or token formats, or renames env vars, the plan MUST include a full migration strategy in that task. The strategy must specify:
    • What changes: which tables, columns, schemas, or data structures are affected
    • Additive or destructive: whether the change is backward-compatible (additive) or breaks existing data (destructive)
    • Rollback approach: how to revert if the migration fails or must be undone
    • Data backfill needs: whether existing records must be transformed, and how (e.g., startup detection of old format + automatic migration, one-time script, lazy migration on read) Add a note in the task: "Migration note: [strategy as described above]". The implementer will log this in MIGRATIONS.md.

Scope Boundaries

This skill:

• DOES: Read Linear issues, explore codebase, read CLAUDE.md, triage issues (cancel invalid ones), write PLANS.md, move valid issues to Todo
• DOES NOT: Write source code, write tests, run tests, deploy, create PRs, modify any file other than PLANS.md

If the user asks to also implement the plan, tell them to use the plan-implement skill after this one completes.

Error Handling

Termination

Follow the termination procedure in references/plans-template.md: output the Plan Summary, then create branch, commit (no Co-Authored-By tags), and push.

Do not ask follow-up questions. Do not offer to implement. Output the summary and stop.