km tc

Analyzes temporal coupling between files via git history. Based on Adam Thornhill’s method (“Your Code as a Crime Scene” ch. 7): files that frequently change together in the same commits have implicit coupling, even without direct imports.

km tc [path]

Formula

Coupling strength = shared_commits / min(commits_a, commits_b)

Coupling levels

Strength	Level	Meaning
>= 0.5	STRONG	Files change together most of the time
0.3-0.5	MODERATE	Noticeable co-change pattern
< 0.3	WEAK	Occasional co-changes

High coupling between unrelated modules suggests hidden dependencies or architectural issues — consider extracting shared abstractions.

Options:

Flag	Description
--format {table,json,short,terse}	Output format (default: table)
--top N	Show only the top N file pairs (default: 20)
--sort-by METRIC	Sort by strength or shared (default: strength)
--since DURATION	Only consider commits since this time (e.g. 6m, 1y, 30d)
--min-degree N	Minimum commits per file to be included (default: 3)
--min-strength F	Minimum coupling strength to show (e.g. 0.5 for strong only)

Example output:

Temporal Coupling — Files That Change Together
──────────────────────────────────────────────────────────────────────────────────
 File A                     File B                     Shared  Strength  Level
──────────────────────────────────────────────────────────────────────────────────
 src/auth/jwt.rs            src/auth/middleware.rs          12      0.86  STRONG
 lib/parser.rs              lib/validator.rs                 8      0.53  STRONG
 config/db.yaml             config/cache.yaml                6      0.35  MODERATE
──────────────────────────────────────────────────────────────────────────────────

12 coupled pairs found (3 shown). Showing pairs with >= 3 shared commits.
Strong coupling (>= 0.5) suggests hidden dependencies — consider extracting shared abstractions.

Note: File renames are not tracked across git history. Renamed files appear as separate entries.