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dart-undead

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Updated 10-15 23:45

About this skill

Dart Undead (dart-undead)

Deterministic reachability and dead/unused declaration analysis for Dart and Flutter packages using pkg:undead.

1. When to Use This Skill

Use this skill when auditing codebase health, trimming dead weight from mature packages, identifying orphaned internal abstractions, or cleaning up standalone applications and CLI tools.

Unlike basic lexical lints (unused_element, unused_field) which only detect unused file-private (_) identifiers, undead builds a whole-package reachability graph from designated entrypoint roots down to all internal declarations.

Trigger Indicators

  • Orphaned Internal Utilities: Functions, classes, or mixins under lib/src/ unreachable from public API barrels or internal entrypoints.
  • Dead Application Features: Unreachable views, controllers, or services in standalone CLI tools or Flutter apps.
  • Orphaned Test Fixtures: Dead Fake* or Mock* fixtures left behind after features were refactored.
  • Pre-Release API Pruning: Verifying whether newly introduced experimental helpers are actually wired up before public release.

When NOT to Use

  • Single-File Private Lints: Rely on standard dart analyze for simple local variable or private parameter lints.
  • Code Formatting or Lint Rules: Use standard dart format or dart fix.
  • Non-Dart / Non-Flutter Projects: Tool exclusively operates on Dart ASTs.

2. Automated Execution & Scope Resolution

Execute the official package CLI directly in the terminal to retrieve reachability findings deterministically:

dart run undead@^0.1.1 [options] [target_path]

[!NOTE]

Pre-Flight Package Resolution Gate: package:analyzer requires .dart_tool/package_config.json to resolve package:<name>/... imports. If packages are unresolved, pass --pub-get to automatically run dart pub get or flutter pub get. If encountering .dart_tool atomic rename errors in sandboxed environments, pass --no-precompile (e.g. dart run --no-precompile undead@^0.1.1).

Execution Modes

Mode 1: Library Package (Default / Open-World)

Preserves all non-src lib/** exports as public API roots. Analyzes whether internal declarations (lib/src/**) are reachable from exported barrels or tests:

# Markdown output for human review
dart run undead@^0.1.1

# Machine-readable JSON output for agent automation
dart run undead@^0.1.1 --format=json

Mode 2: Closed Application (--mode=closed-app)

Traces execution strictly from executable entrypoints (bin/**, lib/main.dart, lib/main_*.dart). Treats unreferenced public declarations as dead:

dart run undead@^0.1.1 --mode=closed-app

Mode 3: Example Code Handling (--example-mode)

Controls how code in example/ is treated during reachability analysis:

  • demonstration (Default): example/ code is treated as a consumer root; example files are never suggested for deletion.
  • strict: Analyzes reachability within example/ itself.
  • skip: Ignores example/ completely during analysis.
dart run undead@^0.1.1 --example-mode=demonstration

Common CLI Options Reference

Option / Flag Purpose Default
-m, --mode Analysis mode (library or closed-app). library
-f, --format Output formatting (markdown, json, github). markdown
--json-output=<path> Write JSON report to file while preserving stdout. None
--example-mode Policy for example/ (demonstration, strict, skip). demonstration
--extra-roots=<dir1,dir2> Comma-separated list of additional root/test dirs. ""
--test-support-patterns Comma-separated wildcards for test fixtures. Fake*,Mock*
--ignore-name-patterns Comma-separated wildcards for names to ignore. ""
--[no-]workspace-discovery Discover consumer roots from sibling packages in workspace. true
--[no-]ignore-external-bindings Preserve unreferenced @JS() and FFI facades. false
--[no-]suggest-private Identify top-level declarations that can be made library-private. false
--pub-get Auto-run dart pub get / flutter pub get if needed. false
--fail-on-undead Exit with non-zero code (1) on findings (useful for CI). false

3. Critical Safety Guardrails & Deletion Invariants

[!CAUTION]

Audit Before Deleting: Never delete declarations autonomously without reviewing safety invariants and verifying against the test suite.

Invariant 1: Sealed Class Hierarchy Protection

Direct subtypes of live sealed classes (via extends, implements, with, or enum) must NEVER be deleted, even if unreferenced elsewhere. Deleting a sealed subtype breaks Dart 3 exhaustive pattern matching across all switch expressions.

Invariant 2: Co-Invoked Test Hazard Protection

When a test file invokes both live and dead declarations:

  • Isolated Dead Tests: Test blocks referencing only dead code can be safely pruned alongside the dead target.
  • Co-Invoked Test Hazard: When a single test function or widget test exercises both live and dead code, do not delete the test. Refactor the test body to remove only the dead assertions.

Invariant 3: Framework Entrypoints & Pragmas

Ensure framework-specific roots are not falsely classified as dead:

  • Build Runner: Builder factories and generator entrypoints in build.yaml.
  • VM Entrypoints: Declarations annotated with @pragma('vm:entry-point').
  • JS Interop: External JavaScript facades (@JS()). Pass --ignore-external-bindings if pruning libraries with public interop headers.

Invariant 4: Custom Suppression Syntax

To suppress intentional dead code or API placeholders without deleting:

  • Declaration Level: // undead:ignore (directly above the declaration; see Placement Rules below).
  • File Level: // undead:ignore_for_file (below the copyright header; see Placement Rules below).
  • (Note: The standard // ignore: unreachable_from_main is strictly for the built-in Dart analyzer lint rule; pkg:undead requires // undead:ignore).

Placement Rules (violations fail dart analyze --fatal-infos or style review):

  • File-level: Insert // undead:ignore_for_file below any copyright / license header block and above the library directive or first import. Never place it on line 1 above the copyright notice.

  • Declaration-level: Never insert // undead:ignore between an existing // ignore: <lint> comment and its declaration. The analyzer only honors an // ignore: comment on the line immediately preceding the declaration, so detaching it produces unnecessary_ignore plus the original diagnostic (e.g. unreachable_from_main). Place // undead:ignore above the // ignore: line:

    // undead:ignore
// ignore: unreachable_from_main
Future<void> runTests(List<String> args) async { ... }

Invariant 5: Dynamic Invocation & Non-AST Reference Check

Static AST analysis (pkg:undead) only traces typed Dart import trees. It cannot see declarations referenced through runtime meta-programming:

  • Dynamic isolate spawners (dart.runInIsolate, Isolate.spawnUri)
  • Code-generation string templates ('''import "package:.../foo.dart";''')
  • JS / WASM compilation targets and runtime asset bootstrap runners
  • Build hooks and build.yaml references
  • Framework extension hooks and plugin registries invoked by downstream runners rather than by in-package call sites

Dynamic-Entrypoint Heuristics (Require Confirmation, Never Blind Delete):

Treat a zero-reference finding as a suspected runtime entrypoint, not dead code, when it matches any of these patterns. Classify it as KEEP (protect with // undead:ignore) unless the user explicitly confirms removal:

  • File names: *_run.dart, direct_run.dart, *_bootstrap.dart, *_listener.dart, *_hook.dart, *_plugin.dart.
  • Declaration names: register*, initialize*, bootstrap*, plugin*, custom*, install*, configure* (e.g. registerReporter).
  • Shape: public top-level functions whose only parameters are callbacks or factories, accepting a string key (registerX(String name, Factory f)), or that spawn isolates / compile kernels / open ports.
  • Context: packages consumed as frameworks (test runners, build systems, plugin hosts) where downstream packages are the real callers.

The Pre-Deletion Check Protocol:

  1. Before deleting any candidate file or top-level declaration in lib/src/, perform a literal string search (grep_search "<filename_or_symbol>") across the repository.
  2. If text matches exist outside the target file itself, inspect and understand the match context before deleting:
    • KEEP: The match is an active runtime string template, dynamic isolate entrypoint, or compilation target. Protect it with // undead:ignore.
    • PRUNE: The match is merely a doc comment, obsolete README reference, or dead test fixture that should be deleted alongside the target.

Invariant 6: Monorepo & External Entrypoint Protection

In multi-package workspaces where internal implementation libraries export entrypoints consumed by sibling CLI wrappers or test runners:

  • Include sibling packages and root integration test folders using --extra-roots or enable --workspace-discovery.
  • If an unexported function is an intended external entrypoint, protect it with // undead:ignore (and // ignore: unreachable_from_main if analyzer lint is active, ordered per the Invariant 4 Placement Rules).

Invariant 7: Cohesive Subsystem Pruning

When pruning dead code, avoid partial or purely cosmetic deletions that leave larger unreferenced subsystems intact:

  • Delete all verified unreferenced internal classes, functions, and files in lib/src/ (e.g., unreferenced listener classes, unused event sinks, obsolete scaffold runners) in one cohesive pass.
  • Remove orphaned imports, associated dead private helpers, and obsolete test fixtures concurrently.

Invariant 8: Deletion Hygiene (Comments Travel With Declarations)

A deletion range must cover the entire declaration, including everything attached above it, so that nothing is left orphaned:

  • Doc comments: Remove the full preceding /// block (and any /** */ block). An orphaned block at file head (before library / import directives) triggers dangling_library_doc_comments under dart analyze --fatal-infos, but an orphan stranded between surviving declarations produces no diagnostic at all and silently re-attaches to the next declaration — only a diff review catches it.
  • Annotations and // ignore: comments: Remove @Deprecated(...), @visibleForTesting, and any // ignore: <lint> lines that belonged to the deleted declaration; a leftover // ignore: triggers unnecessary_ignore.
  • Ignore comments on surviving neighbors: When deleting one of several adjacent declarations, do not leave two // ignore: lines stacked on the survivor (unnecessary_ignore / duplicate_ignore).
  • Blank lines: Collapse the resulting double blank line so dart format reports no changes.

4. The 2-Stage Triage & Confirmation Protocol

To prevent accidental deletions of public APIs or breaking downstream consumers, follow this strict 2-stage workflow:

Stage 1: Read-Only Audit & Reporting (Mandatory Stop)

Run dart run undead@^0.1.1 --format=markdown (or --format=json).

Mandatory Persistent Artifact: You MUST create a structured Markdown artifact named undead_triage_report.md in <appDataDir>/brain/<conversation-id>/. The artifact must include:

  1. Target Summary: Package name, analysis mode (library vs closed-app), and total undead declarations detected.
  2. Actionable Findings Table: Clickable file link, line number, declaration type (class, function, method, variable), and name. Must include code snippets.
  3. Safety Annotations: Highlight any sealed subtypes, co-invoked test hazards, or public exports.

Visible Chat Pre-Render: You MUST render a high-level summary and a direct clickable link to the triage report artifact in visible chat BEFORE invoking the confirmation gate.

Stage 2: Interactive User Confirmation Gate

Anti-Blind-Modal Invariant: Strictly FORBID calling ask_question in the same step as an unrendered report without the report already existing on disk and in chat. The question prompt in ask_question should explicitly reference the generated triage artifact (e.g., "Based on the findings in undead_triage_report.md...").

Pause execution and prompt the user (via interactive choice or chat) to select the desired remediation scope:

  1. (Recommended) Prune All Verified Dead Subsystems & Files: Concurrently delete all unreferenced internal classes, functions, and files in lib/src/** and isolated dead test files.
  2. Prune Application Entrypoints: Target dead features in a closed app (--mode=closed-app).
  3. Suppress Findings: Add // undead:ignore comments to intentional placeholders.
  4. Report-Only / Exit: Acknowledge findings without code mutations.

Explicit Bypass & Non-Interactive Fallback:

  • Direct Directives: Skip Stage 1 pause if given explicit remediation instructions (e.g., "Prune dead code in pkgs/foo using dart-undead").
  • Non-Interactive Execution: In unattended or automated evaluation workflows (e.g. evalin or subagents), proceed with Option 1 (Prune All Verified Dead Subsystems) automatically after verifying baseline tests pass.

5. Pre & Post Deletion Verification Protocol

Always wrap code deletions in a strict test and analysis sandwich:

  1. Pre-Flight Baseline:
    • Check pubspec.yaml: if sdk: flutter is declared, run flutter test; otherwise run dart test.
    • Confirm test suite is 100% green before touching code.
  2. Surgical Deletion: Remove the flagged declaration together with its attached doc comments, annotations, and // ignore: lines (Invariant 8), plus any orphaned imports.
  3. Post-Flight Verification:
    • Run dart analyze --fatal-infos (or flutter analyze --fatal-infos). Plain dart analyze exits 0 on info diagnostics, but many ecosystem CI pipelines (e.g. dart-lang/test) run with --fatal-infos, so dangling_library_doc_comments, unnecessary_ignore, duplicate_ignore, unused_import, and directives_ordering must all be resolved before committing.
    • Run dart format --output=none --set-exit-if-changed . to confirm no formatting drift from collapsed deletion ranges.
    • Run flutter test or dart test to confirm all remaining tests pass.
    • Monorepo Downstream Gate: In multi-package repositories, run tests across all dependent workspace packages and root integration tests before staging.
    • Repository Policies: If the repository enforces changelog tracking, update CHANGELOG.md alongside the change.
  4. Clean Diff Staging: Inspect git diff --stat to ensure only intended declarations were removed, then read the git diff hunks themselves for stranded /// doc comment, annotation, or // ignore: lines that the analyzer cannot flag (Invariant 8).

6. Pull Request & Commit Provenance Protocol

When staging pruned code and preparing a commit message or Pull Request:

1. User Confirmation Gate

  • Interactive Sessions: Before writing the PR description or commit body, explicitly prompt the user in chat or via the harness confirmation tool (e.g. ask_question) whether to include a Tool Provenance & Reproduction block.
  • User Prompt Inclusion: When the user explicitly requests inclusion (or confirms via prompt), append the standardized markdown block below. In unattended or automated workflows, output the summary to chat or step summaries rather than modifying commit bodies without user confirmation.

2. Standardized Provenance Block Format

When confirmed by the user, include the following markdown block in the PR description or commit body so reviewers understand where the deletions originated and can rerun the reachability analysis locally:

### 🤖 Tool Provenance & Reproduction

Dead code detection and reachability analysis performed with
[`undead`](https://pub.dev/packages/undead) (`v{version}`).

To reproduce or re-run this reachability audit locally:

```bash
{exact_command_line}
```

3. Version Resolution

Determine the package version dynamically:

  • Check pubspec.lock in the workspace or run dart run undead@^0.1.1 --version.
  • If invoked with a specific version constraint (e.g. undead@^0.1.1), use that exact version.