Changed lines and raw churn

Changed counts added-only, deleted-only, and modified line positions. Raw churn counts every addition and deletion. Both describe the selected diff; neither is a judgment about the work.

Count a replacement once

The complete three-line replacement patch contains one edit block with three deletions followed by three additions. It has 3 modified, 0 added-only, and 0 deleted-only lines: 3 Changed, alongside 6 raw churn.

From a built source checkout, run the checked executable against the complete local example:

node dist/lib/cli/main.js analyze --diff-file docs/examples/diffs/replacement.diff --no-config --preset size@1 --format human --color never

The patch contains no contextual line between the deletions and additions, so they belong to one contiguous edit block. “Modified” is this positional counting rule. It does not claim a semantic correspondence between particular old and new text.

Keep the components separate

For one edit block with A raw additions and D raw deletions:

Modified     = min(A, D)
Added only   = A - Modified
Deleted only = D - Modified
Changed      = Added only + Deleted only + Modified
Raw churn    = A + D

Two removed lines followed by three added lines therefore contribute 2 modified and 1 added-only line: 3 Changed / 5 churn. A pure addition contributes only added-only lines; a pure deletion contributes only deleted-only lines.

Apply this calculation per edit block, then sum it. A context line, hunk boundary, or file boundary ends a block. Taking max(total additions, total deletions) for an entire file can incorrectly pair unrelated edits. Moving text between separated locations is not automatically discounted as one replacement.

For applicable text measurements, the standard relationships remain:

Raw additions = Added only + Modified
Raw deletions = Deleted only + Modified
Raw churn     = Changed + Modified

These relationships are part of the measurement model, not a second weighting formula selected by the UI.

Account for the complete small example

The payments review patch is the same complete input used by the local quickstart. With no exclusions, its accounting is:

File	Added only	Modified	Changed	Raw churn
`src/payments.ts`	1	2	3	5
`tests/payments.test.ts`	2	0	2	2
`docs/payments.md`	1	0	1	1
`package-lock.json`	0	4	4	8
Total	4	6	10	16

The shared presenter generates this result from that patch during the manual build:

diffdevil analysis
unified-diff · comparison-fc6863bc2513e9fa1125c92c5a186717ce7a4bf70ef48aa145b422f842bebc8c · supplied · = exact

Changed    10 lines
  +4 added only · -0 deleted only · ~6 modified

Raw        +10 additions · -6 deletions · 16 churn
Files      4 total · 4 included · 0 excluded

Policy
  Band       size → xs
  Metrics    review 10

The four-line lockfile replacement contributes four Changed even though most of its text looks similar. The supplied diff presents all four lines as replaced; the engine measures that diff, not an imagined better patch.

Observed files and included totals

An explicit path policy can exclude the lockfile from the measured population. The observed comparison still contains four files. Three are then included and one excluded; their included totals are 6 Changed / 8 churn:

node dist/lib/cli/main.js analyze --diff-file docs/examples/diffs/review.diff --no-config --preset size@1 --exclude package-lock.json --format human --color never

Exclusion does not delete the file’s observed record or claim that the PR itself became smaller. Inspect the selected population before comparing totals from two reports. Paths and scopes is the next-depth guide; the real lockfile lesson lets you inspect the same distinction on a frozen public PR.

The same total can have a different distribution

Ten Changed in one file and ten Changed spread across ten files share a line total, not a file distribution. Keep file counts and scopes beside the total when that distinction matters. The similar-size, different-spread lesson compares real source editions without turning spread into a risk score.

Missing patch blocks can leave Changed bounded even when raw additions and deletions are exact. Binary material can be unmeasurable in lines. Do not apply the exact formulas to missing evidence as though it were zero; continue with Evidence and uncertainty.

For command and output details, use the CLI reference. The separate larger presenter fixture is 178 Changed; it is not another expected output for this 10-Changed patch.