km dups

Finds duplicate code blocks across files using a sliding window approach. Applies the Rule of Three: duplicates appearing 3+ times are marked as CRITICAL (refactor recommended), while those appearing twice are TOLERABLE.

Test files and directories are excluded by default, since tests often contain intentional repetition.

km dups [path]

Options:

Flag	Description
-r, --report	Show detailed report with duplicate locations and code samples
--show-all	Show all duplicate groups (default: top 20)
--min-lines N	Minimum lines for a duplicate block (default: 6)
--include-tests	Include test files in analysis (excluded by default)
--max-duplicates N	Exit with code 1 if duplicate groups exceed this limit (--max-duplicates 0 fails on any duplicate)
--max-dup-ratio PERCENT	Exit with code 1 if the duplicated-lines ratio exceeds this percentage (e.g. --max-dup-ratio 5.0)
--fail-on-increase REF	Exit with code 1 if the current duplication ratio is higher than at the given git ref (e.g. origin/main). Prevents debt from growing silently in CI
--format {table,json,short,terse}	Output format (default: table)

Example summary output:

────────────────────────────────────────────────────────────────────
 Duplication Analysis

 Total code lines:                                             3247
 Duplicated lines:                                              156
 Duplication:                                                  4.8%

 Duplicate groups:                                               12
 Files with duplicates:                                           8
 Largest duplicate:                                        18 lines

 Rule of Three Analysis:
   Critical duplicates (3+):     7 groups,    96 lines
   Tolerable duplicates (2x):    5 groups,    60 lines

 Assessment:                                                    Good
────────────────────────────────────────────────────────────────────

Example detailed output (--report):

────────────────────────────────────────────────────────────────────
 [1] CRITICAL: 18 lines, 3 occurrences (36 duplicated lines)

   src/parser.rs:45-62
   src/formatter.rs:120-137
   src/validator.rs:89-106

 Sample:
   fn process_tokens(input: &str) -> Vec<Token> {
       let mut tokens = Vec::new();
       for line in input.lines() {
       ...

────────────────────────────────────────────────────────────────────
 [2] TOLERABLE: 12 lines, 2 occurrences (12 duplicated lines)

   src/main.rs:100-111
   src/cli.rs:200-211

 Sample:
   match result {
       Ok(value) => {
       ...
────────────────────────────────────────────────────────────────────

Excluded test patterns

By default, km dups skips files matching common test conventions:

• Directories: tests/, test/, __tests__/, spec/
• By extension: *_test.rs, *_test.go, test_*.py, *.test.js, *.spec.ts, *Test.java, *_test.cpp, and more

Use --include-tests to analyze test files as well.