Make plan init tool-agnostic

Acceptance Criteria

• plan init generates a standalone plan/INSTRUCTIONS.md containing the full workflow guide (CLI commands, ID conventions, status workflows, content structure)
• The generated instructions file contains no references to any specific AI tool
• plan init --agent claude appends a short pointer to CLAUDE.md referencing the instructions file
• plan init --agent cursor appends to .cursorrules
• plan init --agent copilot appends to .github/copilot-instructions.md
• plan init --agent none skips appending to any instruction file
• Default behavior (no --agent flag) auto-detects by checking which instruction files exist in the project root
• Auto-detect falls back to CLAUDE.md when no known instruction files are found
• The appended content is a short summary with a pointer to the full instructions file, not the full workflow docs
• Existing plan/CLAUDE.md content is migrated to the new plan/INSTRUCTIONS.md with Claude-specific framing removed
• site/content/runes/plan/workflow.md rewritten as general "AI assistant integration" guide (currently Claude Code-specific)
• site/content/runes/plan/index.md references to CLAUDE.md updated
• site/content/runes/plan/cli.md references to CLAUDE.md updated

Approach

Files to modify

• runes/plan/src/commands/init.ts — replace WORKFLOW_SECTION with a short pointer template; add --agent flag handling; generate INSTRUCTIONS.md
• runes/plan/src/cli-plugin.ts — wire --agent argument through to handleInit
• runes/plan/src/commands/templates.ts — may need a new template for the instructions file content

Agent detection

Check for existence of these files in the project root (in order):

1. CLAUDE.md
2. .cursorrules
3. .github/copilot-instructions.md
4. .windsurfrules
5. .clinerules

Append to all that exist. If none exist, create CLAUDE.md for backwards compatibility.

Pointer content

The appended snippet should be roughly:

## Plan

Project planning content lives in `plan/` using `@refrakt-md/plan`. See `plan/INSTRUCTIONS.md` for the full workflow guide.

Quick start: `refrakt plan next` | `refrakt plan status` | `refrakt plan create work --title "..."`

References

• Plan Package Onboarding & Conventions Review — parent spec

Resolution

Completed: 2026-04-14

Branch: claude/plan-package-review-Z4sJE

What was done

• Added --agent flag to plan init (claude, cursor, copilot, windsurf, cline, none)
• plan init now generates plan/INSTRUCTIONS.md with full tool-agnostic workflow guide
• Auto-detection: checks project root for existing agent instruction files, appends pointer to all found
• Short pointer section appended to agent files instead of full workflow docs
• InitResult.claudeMdUpdated replaced with agentFilesUpdated: string[]
• Rewrote site/content/runes/plan/workflow.md as generic AI assistant guide
• Updated CLAUDE.md and site doc references
• Renamed plan/CLAUDE.md to plan/INSTRUCTIONS.md
• 27 tests covering all agent modes (auto-detect, explicit, none)

Files changed

• runes/plan/src/commands/init.ts — core logic + INSTRUCTIONS_CONTENT + agent detection
• runes/plan/src/cli-plugin.ts — --agent arg wiring
• runes/plan/test/init.test.ts — new agent mode tests
• site/content/runes/plan/workflow.md — rewritten
• site/content/runes/plan/index.md — updated references
• site/content/runes/plan/cli.md — updated init section + fixed milestone dir bug