Granular Git

Stage and commit exact file content without touching the working directory.

Core Concept

Standard Git: Working Directory → Staging Area → Commit

This skill reverses the flow: the agent constructs the exact desired file state in memory and injects it directly into the Staging Area.

[Target State] → hash-object → update-index → commit

The physical file on disk is never modified.

Procedure

1. Determine Target State

Read current index state if there are existing staged changes to preserve:

git show :0:path/to/file.txt

Apply character-level edits to that string (not the disk file).

2. Write as Git Object

TARGET_SHA=$(printf '%s' "$TARGET_CONTENT" | git hash-object -w --stdin)

3. Map to Index

For tracked files:

git update-index --cacheinfo 100644,"$TARGET_SHA","path/to/file.txt"

For brand-new files:

git update-index --add --cacheinfo 100644,"$TARGET_SHA","path/to/file.txt"

4. Commit

git commit -m "type(scope): description"

Multi-Commit Pattern

For multiple independent changes in one file:

HEAD → Commit 1 (Change A) → Commit 2 (A+B) → Commit 3 (A+B+C)

1. Construct target state for Change A only
2. Commit
3. Add Change B to target state, commit
4. Repeat for Change C

Safety Checklist

• Is Git initialized? — git rev-parse --is-inside-work-tree
• Existing staged changes? — Read via git show :0:<file> and merge
• Repo in clean state? — No ongoing merge/rebase

Advantages Over Patches

Example

File on disk has Bug fix + Refactor + Docs. You want to commit only the bug fix:

# 1. Read HEAD version
git show HEAD:src/utils.py

# 2. Create target state (HEAD + bug fix only)
TARGET_SHA=$(printf '%s' "$FIXED_CONTENT" | git hash-object -w --stdin)

# 3. Stage just the bug fix
git update-index --cacheinfo 100644,"$TARGET_SHA","src/utils.py"

# 4. Commit bug fix
git commit -m "fix: correct null pointer check"

# 5. Now repeat for refactor...