Coco Blame

coco blame <file> runs git blame and optionally asks an LLM to explain why each blamed range was introduced.

Basic Usage

bash

1# Standard blame output (no AI, no API key needed)
2coco blame src/index.ts
3
4# Blame a specific line range
5coco blame src/index.ts --lines 10:50
6
7# Ask the LLM to explain the introducing commits
8coco blame src/index.ts --lines 10:50 --explain
9
10# JSON output
11coco blame src/index.ts --explain --json

Options

Flag	Default	Description
`<file>` (positional)	required	Repo-relative path to the file to blame
`--lines <range>`	entire file	Limit to a 1-based inclusive line range: `"10:20"`, `"10:"` (open-ended), or `"10"` (single line)
`--explain`	`false`	Send the blamed commits to the LLM for a natural-language explanation of why each range was introduced
`--json`	`false`	Emit machine-readable JSON output

Plain Blame (no `--explain`)

Without --explain, coco blame prints a formatted table of blame annotations (commit hash, author, date, line number, content). This mode requires no API key and makes no network calls beyond git blame itself.

AI-Powered Explanation (`--explain`)

With --explain, coco:

Groups the blamed lines by introducing commit hash.
Fetches the full commit detail (message, diff stats) for each unique commit.
Sends the grouped context to the configured LLM and asks it to explain, per commit, why those lines were written.
Prints both the blame table and the per-commit explanations.

Cost Guardrails

To prevent runaway cost on large files:

Line cap: --explain is limited to 400 lines. Narrow the range with --lines if you exceed this.
Commit cap: At most 25 unique commits are explained per invocation. If the range touches more, the oldest are truncated with a note.
Uncommitted/staged lines (the all-zero sha) are always excluded from explanation.

Example Output

$ coco blame src/lib/config/types.ts --lines 1:30 --explain

 Hash     Author       Date        Line  Content
 a1b2c3d  gfargo       2026-03-12     1  import { ... }
 a1b2c3d  gfargo       2026-03-12     2  ...
 f4e5d6c  contributor  2026-05-01    15  export type LLMProvider = ...
 ...

Explanations:

a1b2c3d (gfargo, 2026-03-12)
  Initial module scaffold — established the config type hierarchy and
  provider union for the langchain integration layer.

f4e5d6c (contributor, 2026-05-01)
  Added the OpenAI-compatible provider presets (deepseek, groq, xai, etc.)
  to the LLMProvider union, extending the type system to cover the new
  first-class provider category.

JSON Output

With --json, the output is a structured object:

json

1{
2  "path": "src/lib/config/types.ts",
3  "lines": [ ... ],
4  "explanations": [
5    {
6      "hash": "a1b2c3d...",
7      "shortHash": "a1b2c3d",
8      "author": "gfargo",
9      "lines": "1-14",
10      "subject": "feat: initial config type scaffold",
11      "explanation": "Established the config type hierarchy..."
12    }
13  ]
14}