batch-dead-code-deletion

name	batch-dead-code-deletion
description	Batch-verify and delete dead code: rg-confirm zero callers for N symbols, delete files, run the build once, stage results.
when_to_use	batch dead code, delete dead code, dead code deletion, bulk delete dead, batch delete types, remove dead types, prune dead code, dead code cleanup.
argument-hint	Space-separated symbol names, optionally prefixed with --dry-run. Example: /batch-dead-code-deletion FooService BarHelper IWidgetFactory Example: /batch-dead-code-deletion --dry-run FooService BarHelper
allowed-tools	Bash, Read, Glob, Grep, Write, Edit

Batch Dead-Code Deletion

Verify and delete N dead symbols in one pass. Accepts class names, interface names, or method names.

Step 1: Parse Arguments

• If --dry-run is present: set DRY_RUN mode (report only, no deletions)
• Remaining tokens are the symbol list
• If no symbols provided: print usage and stop

Step 2: Classify Each Symbol

For each symbol, confirm it is dead before touching it. Classify into one of: DEAD (no non-definition references), ALIVE (referenced in src/), TEST-ONLY (referenced only under tests/), or ANCHOR (only reference is a typeof(X).Assembly marker in an architecture-test fixture).

1. Find the defining file(s) — scripts/find.sh --class {Symbol} (or rg -l "class {Symbol}|interface {Symbol}|record {Symbol}" src/).
2. Count references — rg -w "{Symbol}" src/ tests/ -g '*.cs'. Exclude the definition site. For extension methods, the class name never appears at call sites — grep the public method names instead.
3. Cross-check (optional) — the find_dead_code Roslyn MCP tool can suggest candidates, but don't trust it alone (~33% false-positive rate). The rg caller count is authoritative.
4. Flag multi-type files — if the defining file declares more than one type, mark it multi_type (edit, don't delete).

Step 3: Execute Deletions (skip in DRY_RUN)

For each DEAD symbol in a single-type file:

git rm src/{defining_file}

For each DEAD symbol in a multi_type file:

• Read the file
• Edit to remove only the dead type's definition block
• git add the modified file

Delete only DEAD symbols — leave ANCHOR, TEST-ONLY, and ALIVE symbols in place.

For ANCHOR symbols: the typeof(X).Assembly reference in the architecture-test fixture must be repointed to another public type from the same assembly before deletion.

Step 4: Verify Build (skip in DRY_RUN)

scripts/check.sh --no-format --json

One run covers all deletions. If the build fails:

• Parse errors for CS0246 (missing type) or similar
• Report which deletion caused the break
• Print recovery: git checkout -- src/{file} for each failed file

Step 5: Stage Results (skip in DRY_RUN)

scripts/internal/stage.sh --include-new

Step 6: Report

Dead-Code Deletion Report

  Symbols checked:  N
  Deleted:          N (files: ...)
  Multi-type edits: N (removed type X from file Y, ...)
  Skipped (alive):  N (SymbolA: N refs in src/)
  Skipped (anchor): N (SymbolC: typeof ref in file)
  Skipped (test):   N (SymbolD: N refs in tests/ only)
  Build status:     PASS / FAIL
  Recovery:         git checkout -- src/{file}

Rules

• Delete only after classification confirmation. Every symbol must be confirmed DEAD (zero non-definition references) before deletion.
• Don't trust find_dead_code alone. ~33% false-positive rate — confirm with rg.
• Extension class gotcha. Grep the public method names, not the class name.
• Multi-type files: edit, don't delete.
• One build run. After all deletions, not per symbol.
• Stage only — don't commit. The caller handles commits.
• DRY_RUN is default-safe. No files modified; report what would happen.