Feature request: `ignorePatterns` setting to hide paths from pi tools

[floogy]

Summary

Add an ignorePatterns (or ignorePaths) array to settings.json that causes pi's built-in tools (read, bash globbing helpers, any future grep/glob/ls tools, autocomplete file pickers, @file mentions, etc.) to refuse or skip matching paths by default.

Today the only way to keep pi away from directories like .svn, node_modules, build outputs, vendored code, secrets, or very large data dirs is to instruct the model via AGENTS.md. That is:

• Best-effort only — the model can still read or bash cat the file.
• Wasteful — instructions must be repeated per project/globally and burn context.
• Inconsistent — different models honor it to varying degrees.

A declarative setting would make this a hard guardrail in the tool layer.

Motivating examples

• SVN working copies: .svn/ at any depth contains huge text-base blobs that destroy context windows and leak old source.
• node_modules/, vendor/, .venv/, dist/, build/, .next/, target/ — rarely what you want the agent reading.
• Secrets dirs: .env*, secrets/, *.pem, *.key.
• Generated caches: .aider.tags.cache.*, .mypy_cache/, __pycache__/.

Proposed shape

{
  "ignorePatterns": [
    "**/.svn/**",
    "**/node_modules/**",
    "**/.venv/**",
    "**/dist/**",
    "**/*.pem",
    "!**/docs/examples/node_modules/**"
  ]
}

Semantics (mirroring the existing resource-loading arrays described in docs/settings.md):

• Gitignore-style globs, matched against absolute and repo-relative paths.
• !pattern re-includes.
• +path / -path force-include / force-exclude exact paths.
• Project .pi/settings.json merges with / overrides ~/.pi/agent/settings.json.

Tool-layer enforcement

When a tool is about to touch a path that matches ignorePatterns:

• read → return a short error like "refused: path matches ignorePatterns (\"**/.svn/**\"). Override with +path in settings or ask the user."
• edit / write → same refusal.
• bash → not filtered (too invasive), but pi could inject a reminder into the system prompt listing the ignore globs so the model naturally scopes find/rg/grep calls. Optionally a bashIgnoreHint: true setting.
• Autocomplete / @file pickers / file listing tools → silently skip matching entries.
• Session file tracking, /tree, and context summarization → skip matching entries.

Escape hatch

• Per-call: allow the model to pass { bypassIgnore: true } with a reason string, which surfaces a user confirmation prompt (similar to destructive-command confirmation).
• Per-settings: +path override as noted above.

Relationship to .gitignore

Tempting to just "respect .gitignore," but I'd argue not by default:

• Many git-ignored paths are exactly what the agent should read: .env.example, lockfiles, dist/ when debugging a shipped bug, generated clients, build logs, IDE configs, local fixtures.
• Non-git projects (SVN, Perforce, plain dirs) have no .gitignore.
• .gitignore is hierarchical (per-dir files, .git/info/exclude, core.excludesfile) — faithful support is non-trivial and couples pi behavior to git state.
• Confusing failure mode: "why can't pi read my build output?" requires users to debug via git internals.

But it's a reasonable opt-in:

{
  "ignorePatterns": ["**/.svn/**"],
  "ignorePatternsFromGitignore": true
}

When true, pi loads .gitignore (and .git/info/exclude) via a library like ignore and unions the patterns with ignorePatterns. Explicit +path / !pattern entries in ignorePatterns still win, so users can re-include specific git-ignored files they actually want pi to see.

Alternatives considered

1. Document-only approach via AGENTS.md — current state; soft, leaky.
2. Auto-respect .gitignore — see above; viable as opt-in, wrong as default.
3. Filesystem-level (bind mounts, chmod) — works but hostile to non-pi tooling and cross-platform broken.

A dedicated ignorePatterns (with optional .gitignore union) is the minimal, explicit, portable solution.

Nice-to-haves

• /settings UI entry to view/edit the list.
• An /ignored diagnostic showing which patterns are ignored.
• Built-in default set behind an ignorePatternsDefaults: true flag (ships with **/.git/objects/**, **/.svn/**, **/node_modules/**, **/__pycache__/**, etc.) so new users get sane behavior out of the box, overridable by project config.

Version

@mariozechner/pi-coding-agent 0.68.0 on Artix Linux / Node 20.20.1.

[github-actions]

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See CONTRIBUTING.md.

[badlogic]

you have ignored CONTRIBUTING.md. you can do this with an extension.