Namespace copyPackFile destinations with composed pack ID to prevent cross-pack collisions

[bguidolim]

Problem

When two packs define a copyPackFile component with the same destination filename and the same CopyFileType, they collide silently:

1. File level: The second pack's file overwrites the first at the shared path (e.g., ~/.claude/hooks/lint.sh). Last writer wins with no warning.
2. Settings level: For hooks, addHookEntry deduplicates by command string (bash ~/.claude/hooks/lint.sh), so only one settings entry exists. The second pack's addHookEntry call returns false.
3. Artifact ownership: Both packs record the same path/command in their PackArtifactRecord. Removing Pack A strips the hook from settings even though Pack B still needs it. The next sync re-adds it, but there's an inconsistency window.

This affects all CopyFileType cases: hooks, skills, commands, agents, and generic files — any two packs using the same destination filename under the same subdirectory will collide.

Proposed Solution

Use the composed component ID (which already includes the pack prefix, e.g., my-pack.lint-hook) to derive the destination filename, preventing collisions by construction.

For example, a component my-pack.lint-hook with destination: lint.sh would be installed as:

• Current: ~/.claude/hooks/lint.sh
• Proposed: ~/.claude/hooks/my-pack.lint-hook.sh (or similar namespaced scheme)

The hook command in settings would change accordingly:

• Current: bash ~/.claude/hooks/lint.sh
• Proposed: bash ~/.claude/hooks/my-pack.lint-hook.sh

Components to audit

All CopyFileType destinations share a flat namespace per subdirectory:

• .hook → .claude/hooks/
• .skill → .claude/skills/
• .command → .claude/commands/
• .agent → .claude/agents/
• .generic → .claude/

Each needs the same namespacing treatment.

Migration Plan

Existing installations have files at the old (non-namespaced) paths. A migration is required:

1. Detection: On first sync after the change, compare old artifact records (non-namespaced paths) against the new naming scheme.
2. Rename: Move existing files from old paths to new namespaced paths.
3. Settings update: For hooks, remove the old command string from settings and add the new one.
4. Artifact record update: Update PackArtifactRecord entries (files, fileHashes, hookCommands) to reflect new paths.
5. State version bump: Increment the ProjectState version to trigger migration on next sync.
6. Backward compatibility: Consider a transitional period where both old and new paths are recognized during doctor checks, to avoid false positives for users who haven't re-synced yet.

References

• Sources/mcs/TechPack/Component.swift — CopyFileType enum
• Sources/mcs/Install/ConfiguratorSupport.swift — hook command construction (hookCommandPrefix + destination)
• Sources/mcs/Install/GlobalSyncStrategy.swift — hook stripping by prefix match
• Sources/mcs/Install/Configurator.swift — artifact tracking for hook commands