Self-guard hooks when running inside plugin source repo

[b-coman]

Problem

When a developer works on the ido4shape plugin itself (editing skills, agents, scripts), every Claude Code session here fires the plugin's own hooks:

• SessionStart creates a .ido4shape/ workspace inside the plugin repo
• UserPromptSubmit injects canvas context on every prompt
• Stop nags about canvas updates and session summaries
• PreCompact prompts to save spec insights

None of this is relevant when the user is developing the plugin rather than using it. It creates noise, pollutes the repo with a workspace directory, and confuses fresh contributors. The quick workaround is disabling the plugin per-repo via .claude/settings.local.json, but that's a manual step every forker/contributor has to discover.

Proposed fix

Each hook script should detect "I'm running inside my own plugin source repo" and exit early.

Detection logic: walk from CWD up to the git root looking for .claude-plugin/plugin.json. If found, parse it and check name == "ido4shape". If yes, exit 0 silently.

Scope — scripts to guard:

• scripts/session-start.sh (SessionStart)
• scripts/canvas-context.sh (UserPromptSubmit)
• scripts/phase-gate.sh (PreToolUse on Write)

Extract the detection into a shared helper (e.g., scripts/lib/is-plugin-source.sh) so all three stay consistent.

Escape hatch: honor an env var like IDO4SHAPE_FORCE_ACTIVE=1 so plugin maintainers can still exercise the hooks against the plugin itself when testing.

Testing

Unit test for the detection helper — given a fake directory tree, does it correctly identify:

• CWD is the plugin root → true
• CWD is a subdirectory of the plugin root → true
• CWD is an unrelated repo containing a coincidentally-named plugin.json (different `name`) → false
• No plugin.json anywhere in the chain → false
• Escape hatch env var set → hook runs anyway

Integration test — extend tests/validate-plugin.sh:

• Simulate a session-start with CWD inside the plugin source → assert no .ido4shape/ created, no stdout noise
• Simulate with the escape hatch env var set → assert hook runs normally

Manual smoke test — fresh clone of ido4shape, open Claude Code in it, confirm:

• No workspace created
• No canvas prompts injected on every turn
• No Stop hook nagging

Out of scope

• Generalizing this to "any plugin running inside its own source" (other plugins can copy the pattern if useful)
• Documenting the escape hatch in user-facing docs (internal contributor knowledge for now)

Context

Discovered 2026-04-05 when a maintainer session in the ido4shape repo triggered workspace creation and persistent Stop-hook nagging during purely operational work (plugin disable question). Quick fix applied via personal .claude/settings.local.json.