refactor(git-history): retrofit to the ADR-0020 context contract
Description 450 -> 266 chars, body 1044 -> 462 words. The bisect procedure moves to references/bisect.md. The boundary clause read 'not writing or rewriting commits', which disclaimed the cherry-pick and revert this skill's own Step 3 executes; it now excludes authoring and rebasing only. Adds 'backport' so cherry-pick is reachable by natural language at all, accepting 266 chars against a 250 soft target and a 400 ceiling.
This commit is contained in:
@@ -6,6 +6,10 @@ Inspect git history — log queries, bisect, and locating problematic commits.
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This skill handles history inspection within the git workflow suite. It queries logs with pickaxe/line-range/custom formats, runs bisect to find bug-introducing commits, and locates commits for downstream cherry-picking or reverting. It returns structured results for agent composition. Rebase, squash, fixup, and other history-rewriting operations are owned by git-commits, not this skill.
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## Composition
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`git-branches` delegates cherry-pick and revert here (see `git-branches`'s `references/merging.md`), which is why this skill carries those two operations rather than treating them as out of scope. They are general git knowledge, not drawn from the `history-inspection.md` research corpus. Server-side commit history on a Gitea-hosted repository belongs to `gitea-branches`; this skill reads the local working copy.
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## Usage
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```
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@@ -19,6 +23,7 @@ Describe your history task: search logs, bisect for a regression, or locate a sp
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| File | Purpose |
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|------|---------|
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| `SKILL.md` | Skill instructions for agents |
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| `references/git-log-format.md` | Full log format placeholders, diff-filter letters, `-L` syntax, ancestry filters, diff output-control flags |
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| `references/bisect.md` | Loaded when the entry procedure is bisect: manual and automated flows, exit codes, skip, replay, narrowing, custom terms |
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| `references/git-log-format.md` | Loaded when a log or diff flag needs looking up: format placeholders, presets, diff-filter letters, `-L` syntax, ancestry filters, pickaxe binary-file behaviour, diff output-control flags |
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| `references/sources.md` | Research sources and provenance |
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| `references/README.md` | Index of the references directory |
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@@ -2,7 +2,10 @@
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name: git-history
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description: >
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Inspect git history: query logs with pickaxe, line-range, or custom formats; find bug origins via bisect; locate problematic commits for cherry-picking or reverting. Use when investigating history, tracing when a change happened, or finding the commit that broke something. Return structured results for downstream agents. Do not use for authoring or formatting commit messages, or executing rebase/squash/fixup operations — use git-commits for that.
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Use when investigating git history — querying logs, tracing when a change
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landed, bisecting the commit that broke something, or locating one to
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revert or backport. Not authoring or rebasing commits -> `git-commits`.
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Not history on a Gitea server -> `gitea-branches`.
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metadata:
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category: git
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@@ -16,81 +19,47 @@ allowed-tools: Bash
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## Gotchas
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- **Pickaxe searches (`-S` vs `-G`)**: `-S"string"` finds commits where string count changed; `-G"regex"` finds any line matching regex in diffs. They're not equivalent: a line replaced (one removal + one addition) matches `-G` but not `-S` if count is unchanged.
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- **`--follow` only works for single files**: it traces renames but fails with multiple paths or directory globs. Use `git log -- <single-file>` or query without `--follow`.
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- **Bisect with skips**: if bisect cannot pinpoint a commit because the culprit is adjacent to skipped commits, it reports "cannot find exact culprit" and lists candidates. This is not a failure — it's as precise as the skip range allows.
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- **Interactive rebase is non-recoverable on mistake**: there's no undo once `rebase -i` starts. Suggest `git reflog` to recover if the user realizes mid-way they selected the wrong commits.
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- **`-L` (line-range history) requires exact line numbers or regex patterns**: off-by-one errors omit the target range. Test the range with `git log -L` before offering it to users.
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- `-S"string"` matches only where the string's *count* changed, so a line edited in place matches `-G"regex"` and not `-S`. Reach for `-G` whenever the string may have moved rather than appeared.
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- `--follow` traces renames for exactly one path. Given several paths or a glob it fails instead of degrading, so run it once per file.
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- Under `git bisect run`, exit `128` or above **aborts the session** rather than marking the commit bad, so a crashing test script ends the search silently.
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- Bisect answering "cannot find exact culprit" beside skipped commits is a complete result: it is as precise as the skip range allows.
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## Query Logs and Locate Commits
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## Step 1 — Pick the entry procedure
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Default to `git log --oneline` for quick inspection. For deeper queries:
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| What is known | Procedure |
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|---|---|
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| Content, a file, or a line range to search for | Query the log — Step 2 |
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| Nothing to search for — only that the behaviour changed between two points | Bisect — read `references/bisect.md` |
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| The commit itself, already identified | Step 3 |
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- **Find when a string appeared or disappeared**: Use `git log -S"string"` (count-sensitive, finds adds/removes). If you need any mention of the string in diffs, use `git log -G"regex"` instead. Add `--pickaxe-regex` to treat the `-S` string as a POSIX ERE, and `--pickaxe-all` to show every changed file in a matching changeset, not just the matching ones. Binary files are searched by `-S`; `-G` ignores them unless `--text` is also supplied.
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- **Trace changes to a specific line or function**: Use `git log -L <start>,<end>:<file>` or `git log -L :<function>:<file>` (requires function name heuristic). This shows the evolution of that range across all commits.
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- **Filter by change type**: Use `git log --diff-filter=<type>` (A=added, M=modified, D=deleted, R=renamed) to narrow to specific file operations.
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- **Mainline-only history through merges**: Use `--first-parent` to follow only the integration branch and skip merged-in side-branch commits; combine with `--merges`/`--no-merges` or `--ancestry-path`/`--min-parents`/`--max-parents` for other ancestry-graph filtering — see `references/git-log-format.md` for the full set.
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- **Custom format for structured output**: Construct format string with `%h` (hash), `%s` (subject), `%an` (author), `%ar` (relative date), `%b` (body). Example: `git log --format="%h | %s | %an (%ar)"`.
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- **File-specific history with renames**: Use `git log --follow -- <file>` (single file only). Without `--follow`, log stops at the rename boundary.
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## Step 2 — Query the log
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## Bisect to Find Blame Commit
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Default to `git log --oneline`, then narrow by whatever is known:
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Use bisect when hunting for the commit that introduced a bug or behaviour change. Binary search reduces iterations from O(N) to O(log N).
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- **Content**: `git log -S"string"`, or `-G"regex"` to match any diff line. `--pickaxe-regex` makes the `-S` argument a POSIX ERE; `--pickaxe-all` shows every file in a matching changeset.
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- **A line or function**: `git log -L <start>,<end>:<file>` or `git log -L :<function>:<file>`. Confirm the range resolves before reporting on it — an off-by-one silently omits the target.
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- **A file across renames**: `git log --follow -- <file>`. Without `--follow` the history stops at the rename boundary.
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- **Mainline only**: `--first-parent` follows the integration branch and skips commits merged in from side branches.
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- **Structured output**: `git log --format="%h | %s | %an (%ar)"`.
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**Basic manual flow:**
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```bash
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git bisect start
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git bisect bad [HEAD] # mark current (or specified) as broken
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git bisect good <commit> # mark known-good baseline
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# Git checks out midpoint; test it manually
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git bisect good # if test passes
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git bisect bad # if test fails
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# Repeat until git reports "X is the first bad commit"
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git bisect reset # return to original HEAD
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If you need the placeholder catalogue, format presets, `--diff-filter` letters, full `-L` syntax, ancestry filters, pickaxe binary-file behaviour, or `git diff` output-control flags such as `--stat`, `--word-diff` and the whitespace options, read `references/git-log-format.md`.
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## Step 3 — Act on a located commit
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Offer the operation and its consequence; run it only once the user has chosen.
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- `git cherry-pick <commit>` copies the commit's changes onto the current HEAD — for backporting a fix to another branch.
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- `git revert <commit>` adds a new commit undoing it — for un-applying merged work without rewriting history.
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- `git blame <file>` attributes each line to the commit that last touched it, when the question is which commit introduced one specific line.
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For diff output control on the located commit, read `references/git-log-format.md`.
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## Step 4 — Return the result
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Report each located commit in this shape, so a calling agent can act on it without reparsing raw log output:
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```text
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<sha> — <subject>
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<author> (<relative date>)
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Recommendation: <action or "none">
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```
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**Automated with `git bisect run`:** if a test command exists, use `git bisect run <cmd>`. Git interprets the exit code: `0`=good, `1-124`=bad, `125`=skip (build broken), `126-127`=POSIX shell errors treated as bad, `128+`=**aborts the bisect session entirely** (not treated as bad — a crashed test script can silently end the search).
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**With skip:** if a commit is untestable (broken build), use `git bisect skip` to exclude it without manually deciding good/bad. If the first-bad is adjacent to skips, bisect reports it cannot pinpoint but lists candidates.
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**Undoing a wrong good/bad call:** `git bisect log` prints the session's decision history; save it (`git bisect log > bisect.log`), edit out the mistaken entry, then `git bisect reset && git bisect replay bisect.log` to resume from the corrected log instead of restarting the whole search.
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**Narrowing and speeding up the search:** `git bisect start HEAD v1.2 -- src/` limits bisection to a path, cutting the number of trials. `--no-checkout` updates the `BISECT_HEAD` ref instead of checking out a working tree (useful for tests that don't need one; automatic in bare repos). `--first-parent` follows only first parents at merges, finding the integration commit that introduced a regression while ignoring broken side branches.
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**Inspecting remaining candidates visually:** `git bisect visualize` (alias `view`) opens the suspects in gitk; add `--stat` or `-p` to show diffstat or full patches instead. Falls back to `git log` when no graphical display is detected.
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**For non-regression hunts:** use `git bisect start --term-new <new> --term-old <old>` to search for a property change instead of a bug (e.g., performance regression). Then use the custom terms instead of `good`/`bad`.
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For rebase execution (interactive rebase, squash/fixup/reword, conflict handling) see git-commits — it owns history-rewriting operations. This skill only locates commits and reports on history; it does not execute rebases.
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## Find and Manipulate Problematic Commits
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Once a commit is identified (via log query or bisect), offer cherry-pick or revert. This section is general git knowledge, not sourced from `history-inspection.md` — `git-branches`'s SKILL.md explicitly delegates cherry-pick/revert here (see its Merging section), which is why this skill carries them rather than treating them as out of scope:
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- **Cherry-pick**: `git cherry-pick <commit>` copies a commit's changes onto current HEAD. Use when backporting fixes to other branches.
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- **Revert**: `git revert <commit>` creates a new commit that undoes the changes. Use when un-applying a merged commit without rewriting history.
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- **Blame for context**: `git blame <file>` shows which commit last changed each line. Use to trace a specific line back to its introducing commit.
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## Inspect Diffs
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Diff-output tuning is in scope too: `--stat` for a diffstat summary, `--word-diff` for word-level (not line-level) changes, and whitespace flags (`-w`, `--ignore-blank-lines`) to suppress noise from reformatting. See `references/git-log-format.md` for the full flag set.
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## Return Results Structured
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For agent consumption, return:
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- **Commit SHA** (full or abbreviated as appropriate)
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- **Subject line** (from `%s`)
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- **Author and date** (from `%an` and `%ar`)
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- **Action taken or recommended** (e.g., "Found via bisect", "Offer cherry-pick to main", "Rebase conflicts detected")
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Example for agent:
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```
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Found first bad commit: abc1234
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Subject: fix null pointer in parser
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Author: Alice (2 weeks ago)
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Recommendation: Backport to release branch via cherry-pick
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```
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## Reference
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For the full log format placeholder catalogue, named format presets, `--diff-filter` letters, `-L` range syntax, ancestry filters, and `git diff` output-control flags, read `references/git-log-format.md`.
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@@ -12,4 +12,5 @@ This directory contains provenance metadata and research sources for the `git-hi
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## Files
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- `sources.md` — Extracted research sources and their contributing documents
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- `git-log-format.md` — Full `git log` format placeholder catalogue, named format presets, `--diff-filter` letters, `-L` line-range syntax, ancestry filters, and `git diff` output-control flags
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- `bisect.md` — The full `git bisect` procedure: manual and automated flows, exit-code semantics, skip and replay, narrowing options, and custom good/bad terms
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- `git-log-format.md` — Full `git log` format placeholder catalogue, named format presets, `--diff-filter` letters, `-L` line-range syntax, ancestry filters, pickaxe binary-file behaviour, and `git diff` output-control flags
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68
plugins/git/.apm/skills/git-history/references/bisect.md
Normal file
68
plugins/git/.apm/skills/git-history/references/bisect.md
Normal file
@@ -0,0 +1,68 @@
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---
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topic: bisect
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source_keys:
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- git-scm-bisect-docs
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---
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# Finding a commit with `git bisect`
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Read this when the question is *which commit changed the behaviour* and there is no string, file,
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or line range to search the log for. Binary search reduces the trials from O(N) to O(log N).
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## Manual flow
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```bash
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git bisect start
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git bisect bad [HEAD] # mark current (or specified) as broken
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git bisect good <commit> # mark known-good baseline
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# Git checks out the midpoint; test it
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git bisect good # test passes
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git bisect bad # test fails
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# Repeat until git reports "X is the first bad commit"
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git bisect reset # return to the original HEAD
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```
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## Automated
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With a test command available, use `git bisect run <cmd>`. Git reads the exit code: `0` good,
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`1`–`124` bad, `125` skip (build broken), `126`–`127` POSIX shell errors, treated as bad, and
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`128` or above aborts the session outright rather than marking the commit bad.
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## Untestable commits
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`git bisect skip` excludes a commit that cannot be built or tested without deciding good or bad
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for it. When the first bad commit is adjacent to a skipped range, bisect reports that it cannot
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pinpoint the culprit and lists the candidates — that is the precise answer the skip range allows,
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not a failure.
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## Undoing a wrong good/bad call
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`git bisect log` prints the session's decision history. Save it, edit out the mistaken entry, and
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resume from the corrected log rather than restarting the search:
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```bash
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git bisect log > bisect.log
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# edit bisect.log, removing the wrong decision
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git bisect reset && git bisect replay bisect.log
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```
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## Narrowing and speeding up
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- `git bisect start HEAD v1.2 -- src/` restricts bisection to a path, cutting the trial count.
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- `--no-checkout` updates the `BISECT_HEAD` ref instead of checking out a working tree — useful
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for tests that do not need one, and automatic in bare repos.
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- `--first-parent` follows only first parents at merges, finding the integration commit that
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introduced a regression while ignoring broken side branches.
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## Inspecting the remaining candidates
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`git bisect visualize` (alias `view`) opens the suspects in gitk, falling back to `git log` when
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no graphical display is detected. Add `--stat` or `-p` for a diffstat or full patches.
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## Hunting a non-bug property change
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`git bisect start --term-new <new> --term-old <old>` searches for any property change — a
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performance regression, say — instead of a bug. Use the custom terms in place of `good` and `bad`
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for the rest of the session.
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Once the first bad commit is identified, return to Step 3 to act on it and Step 4 to report it.
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@@ -88,7 +88,7 @@ source_keys:
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| `%GK` | signing key ID |
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**Trailers:**
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```
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```text
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%(trailers[:key=<k>][,only][,separator=<s>][,unfold][,keyonly][,valueonly])
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```
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@@ -12,7 +12,7 @@ Git bisect documentation covering binary search through commit history to find t
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- **Research doc:** plugins/git/docs/research/docs/git/history-inspection.md
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- **Doc heading:** `## git bisect`
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- **Contributing files:** SKILL.md
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- **Contributing files:** SKILL.md, references/bisect.md
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## git-scm-log-docs
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@@ -28,4 +28,4 @@ Git diff documentation covering output control (--stat, --name-only, --name-stat
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- **Research doc:** plugins/git/docs/research/docs/git/history-inspection.md
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- **Doc heading:** `## git diff — Output Control`
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- **Contributing files:** references/git-log-format.md
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- **Contributing files:** SKILL.md, references/git-log-format.md
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|
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@@ -6,6 +6,10 @@ Inspect git history — log queries, bisect, and locating problematic commits.
|
||||
|
||||
This skill handles history inspection within the git workflow suite. It queries logs with pickaxe/line-range/custom formats, runs bisect to find bug-introducing commits, and locates commits for downstream cherry-picking or reverting. It returns structured results for agent composition. Rebase, squash, fixup, and other history-rewriting operations are owned by git-commits, not this skill.
|
||||
|
||||
## Composition
|
||||
|
||||
`git-branches` delegates cherry-pick and revert here (see `git-branches`'s `references/merging.md`), which is why this skill carries those two operations rather than treating them as out of scope. They are general git knowledge, not drawn from the `history-inspection.md` research corpus. Server-side commit history on a Gitea-hosted repository belongs to `gitea-branches`; this skill reads the local working copy.
|
||||
|
||||
## Usage
|
||||
|
||||
```
|
||||
@@ -19,6 +23,7 @@ Describe your history task: search logs, bisect for a regression, or locate a sp
|
||||
| File | Purpose |
|
||||
|------|---------|
|
||||
| `SKILL.md` | Skill instructions for agents |
|
||||
| `references/git-log-format.md` | Full log format placeholders, diff-filter letters, `-L` syntax, ancestry filters, diff output-control flags |
|
||||
| `references/bisect.md` | Loaded when the entry procedure is bisect: manual and automated flows, exit codes, skip, replay, narrowing, custom terms |
|
||||
| `references/git-log-format.md` | Loaded when a log or diff flag needs looking up: format placeholders, presets, diff-filter letters, `-L` syntax, ancestry filters, pickaxe binary-file behaviour, diff output-control flags |
|
||||
| `references/sources.md` | Research sources and provenance |
|
||||
| `references/README.md` | Index of the references directory |
|
||||
|
||||
@@ -2,7 +2,10 @@
|
||||
name: git-history
|
||||
|
||||
description: >
|
||||
Inspect git history: query logs with pickaxe, line-range, or custom formats; find bug origins via bisect; locate problematic commits for cherry-picking or reverting. Use when investigating history, tracing when a change happened, or finding the commit that broke something. Return structured results for downstream agents. Do not use for authoring or formatting commit messages, or executing rebase/squash/fixup operations — use git-commits for that.
|
||||
Use when investigating git history — querying logs, tracing when a change
|
||||
landed, bisecting the commit that broke something, or locating one to
|
||||
revert or backport. Not authoring or rebasing commits -> `git-commits`.
|
||||
Not history on a Gitea server -> `gitea-branches`.
|
||||
|
||||
metadata:
|
||||
category: git
|
||||
@@ -16,81 +19,47 @@ allowed-tools: Bash
|
||||
|
||||
## Gotchas
|
||||
|
||||
- **Pickaxe searches (`-S` vs `-G`)**: `-S"string"` finds commits where string count changed; `-G"regex"` finds any line matching regex in diffs. They're not equivalent: a line replaced (one removal + one addition) matches `-G` but not `-S` if count is unchanged.
|
||||
- **`--follow` only works for single files**: it traces renames but fails with multiple paths or directory globs. Use `git log -- <single-file>` or query without `--follow`.
|
||||
- **Bisect with skips**: if bisect cannot pinpoint a commit because the culprit is adjacent to skipped commits, it reports "cannot find exact culprit" and lists candidates. This is not a failure — it's as precise as the skip range allows.
|
||||
- **Interactive rebase is non-recoverable on mistake**: there's no undo once `rebase -i` starts. Suggest `git reflog` to recover if the user realizes mid-way they selected the wrong commits.
|
||||
- **`-L` (line-range history) requires exact line numbers or regex patterns**: off-by-one errors omit the target range. Test the range with `git log -L` before offering it to users.
|
||||
- `-S"string"` matches only where the string's *count* changed, so a line edited in place matches `-G"regex"` and not `-S`. Reach for `-G` whenever the string may have moved rather than appeared.
|
||||
- `--follow` traces renames for exactly one path. Given several paths or a glob it fails instead of degrading, so run it once per file.
|
||||
- Under `git bisect run`, exit `128` or above **aborts the session** rather than marking the commit bad, so a crashing test script ends the search silently.
|
||||
- Bisect answering "cannot find exact culprit" beside skipped commits is a complete result: it is as precise as the skip range allows.
|
||||
|
||||
## Query Logs and Locate Commits
|
||||
## Step 1 — Pick the entry procedure
|
||||
|
||||
Default to `git log --oneline` for quick inspection. For deeper queries:
|
||||
| What is known | Procedure |
|
||||
|---|---|
|
||||
| Content, a file, or a line range to search for | Query the log — Step 2 |
|
||||
| Nothing to search for — only that the behaviour changed between two points | Bisect — read `references/bisect.md` |
|
||||
| The commit itself, already identified | Step 3 |
|
||||
|
||||
- **Find when a string appeared or disappeared**: Use `git log -S"string"` (count-sensitive, finds adds/removes). If you need any mention of the string in diffs, use `git log -G"regex"` instead. Add `--pickaxe-regex` to treat the `-S` string as a POSIX ERE, and `--pickaxe-all` to show every changed file in a matching changeset, not just the matching ones. Binary files are searched by `-S`; `-G` ignores them unless `--text` is also supplied.
|
||||
- **Trace changes to a specific line or function**: Use `git log -L <start>,<end>:<file>` or `git log -L :<function>:<file>` (requires function name heuristic). This shows the evolution of that range across all commits.
|
||||
- **Filter by change type**: Use `git log --diff-filter=<type>` (A=added, M=modified, D=deleted, R=renamed) to narrow to specific file operations.
|
||||
- **Mainline-only history through merges**: Use `--first-parent` to follow only the integration branch and skip merged-in side-branch commits; combine with `--merges`/`--no-merges` or `--ancestry-path`/`--min-parents`/`--max-parents` for other ancestry-graph filtering — see `references/git-log-format.md` for the full set.
|
||||
- **Custom format for structured output**: Construct format string with `%h` (hash), `%s` (subject), `%an` (author), `%ar` (relative date), `%b` (body). Example: `git log --format="%h | %s | %an (%ar)"`.
|
||||
- **File-specific history with renames**: Use `git log --follow -- <file>` (single file only). Without `--follow`, log stops at the rename boundary.
|
||||
## Step 2 — Query the log
|
||||
|
||||
## Bisect to Find Blame Commit
|
||||
Default to `git log --oneline`, then narrow by whatever is known:
|
||||
|
||||
Use bisect when hunting for the commit that introduced a bug or behaviour change. Binary search reduces iterations from O(N) to O(log N).
|
||||
- **Content**: `git log -S"string"`, or `-G"regex"` to match any diff line. `--pickaxe-regex` makes the `-S` argument a POSIX ERE; `--pickaxe-all` shows every file in a matching changeset.
|
||||
- **A line or function**: `git log -L <start>,<end>:<file>` or `git log -L :<function>:<file>`. Confirm the range resolves before reporting on it — an off-by-one silently omits the target.
|
||||
- **A file across renames**: `git log --follow -- <file>`. Without `--follow` the history stops at the rename boundary.
|
||||
- **Mainline only**: `--first-parent` follows the integration branch and skips commits merged in from side branches.
|
||||
- **Structured output**: `git log --format="%h | %s | %an (%ar)"`.
|
||||
|
||||
**Basic manual flow:**
|
||||
```bash
|
||||
git bisect start
|
||||
git bisect bad [HEAD] # mark current (or specified) as broken
|
||||
git bisect good <commit> # mark known-good baseline
|
||||
# Git checks out midpoint; test it manually
|
||||
git bisect good # if test passes
|
||||
git bisect bad # if test fails
|
||||
# Repeat until git reports "X is the first bad commit"
|
||||
git bisect reset # return to original HEAD
|
||||
If you need the placeholder catalogue, format presets, `--diff-filter` letters, full `-L` syntax, ancestry filters, pickaxe binary-file behaviour, or `git diff` output-control flags such as `--stat`, `--word-diff` and the whitespace options, read `references/git-log-format.md`.
|
||||
|
||||
## Step 3 — Act on a located commit
|
||||
|
||||
Offer the operation and its consequence; run it only once the user has chosen.
|
||||
|
||||
- `git cherry-pick <commit>` copies the commit's changes onto the current HEAD — for backporting a fix to another branch.
|
||||
- `git revert <commit>` adds a new commit undoing it — for un-applying merged work without rewriting history.
|
||||
- `git blame <file>` attributes each line to the commit that last touched it, when the question is which commit introduced one specific line.
|
||||
|
||||
For diff output control on the located commit, read `references/git-log-format.md`.
|
||||
|
||||
## Step 4 — Return the result
|
||||
|
||||
Report each located commit in this shape, so a calling agent can act on it without reparsing raw log output:
|
||||
|
||||
```text
|
||||
<sha> — <subject>
|
||||
<author> (<relative date>)
|
||||
Recommendation: <action or "none">
|
||||
```
|
||||
|
||||
**Automated with `git bisect run`:** if a test command exists, use `git bisect run <cmd>`. Git interprets the exit code: `0`=good, `1-124`=bad, `125`=skip (build broken), `126-127`=POSIX shell errors treated as bad, `128+`=**aborts the bisect session entirely** (not treated as bad — a crashed test script can silently end the search).
|
||||
|
||||
**With skip:** if a commit is untestable (broken build), use `git bisect skip` to exclude it without manually deciding good/bad. If the first-bad is adjacent to skips, bisect reports it cannot pinpoint but lists candidates.
|
||||
|
||||
**Undoing a wrong good/bad call:** `git bisect log` prints the session's decision history; save it (`git bisect log > bisect.log`), edit out the mistaken entry, then `git bisect reset && git bisect replay bisect.log` to resume from the corrected log instead of restarting the whole search.
|
||||
|
||||
**Narrowing and speeding up the search:** `git bisect start HEAD v1.2 -- src/` limits bisection to a path, cutting the number of trials. `--no-checkout` updates the `BISECT_HEAD` ref instead of checking out a working tree (useful for tests that don't need one; automatic in bare repos). `--first-parent` follows only first parents at merges, finding the integration commit that introduced a regression while ignoring broken side branches.
|
||||
|
||||
**Inspecting remaining candidates visually:** `git bisect visualize` (alias `view`) opens the suspects in gitk; add `--stat` or `-p` to show diffstat or full patches instead. Falls back to `git log` when no graphical display is detected.
|
||||
|
||||
**For non-regression hunts:** use `git bisect start --term-new <new> --term-old <old>` to search for a property change instead of a bug (e.g., performance regression). Then use the custom terms instead of `good`/`bad`.
|
||||
|
||||
For rebase execution (interactive rebase, squash/fixup/reword, conflict handling) see git-commits — it owns history-rewriting operations. This skill only locates commits and reports on history; it does not execute rebases.
|
||||
|
||||
## Find and Manipulate Problematic Commits
|
||||
|
||||
Once a commit is identified (via log query or bisect), offer cherry-pick or revert. This section is general git knowledge, not sourced from `history-inspection.md` — `git-branches`'s SKILL.md explicitly delegates cherry-pick/revert here (see its Merging section), which is why this skill carries them rather than treating them as out of scope:
|
||||
|
||||
- **Cherry-pick**: `git cherry-pick <commit>` copies a commit's changes onto current HEAD. Use when backporting fixes to other branches.
|
||||
- **Revert**: `git revert <commit>` creates a new commit that undoes the changes. Use when un-applying a merged commit without rewriting history.
|
||||
- **Blame for context**: `git blame <file>` shows which commit last changed each line. Use to trace a specific line back to its introducing commit.
|
||||
|
||||
## Inspect Diffs
|
||||
|
||||
Diff-output tuning is in scope too: `--stat` for a diffstat summary, `--word-diff` for word-level (not line-level) changes, and whitespace flags (`-w`, `--ignore-blank-lines`) to suppress noise from reformatting. See `references/git-log-format.md` for the full flag set.
|
||||
|
||||
## Return Results Structured
|
||||
|
||||
For agent consumption, return:
|
||||
- **Commit SHA** (full or abbreviated as appropriate)
|
||||
- **Subject line** (from `%s`)
|
||||
- **Author and date** (from `%an` and `%ar`)
|
||||
- **Action taken or recommended** (e.g., "Found via bisect", "Offer cherry-pick to main", "Rebase conflicts detected")
|
||||
|
||||
Example for agent:
|
||||
```
|
||||
Found first bad commit: abc1234
|
||||
Subject: fix null pointer in parser
|
||||
Author: Alice (2 weeks ago)
|
||||
Recommendation: Backport to release branch via cherry-pick
|
||||
```
|
||||
|
||||
## Reference
|
||||
|
||||
For the full log format placeholder catalogue, named format presets, `--diff-filter` letters, `-L` range syntax, ancestry filters, and `git diff` output-control flags, read `references/git-log-format.md`.
|
||||
|
||||
@@ -12,4 +12,5 @@ This directory contains provenance metadata and research sources for the `git-hi
|
||||
## Files
|
||||
|
||||
- `sources.md` — Extracted research sources and their contributing documents
|
||||
- `git-log-format.md` — Full `git log` format placeholder catalogue, named format presets, `--diff-filter` letters, `-L` line-range syntax, ancestry filters, and `git diff` output-control flags
|
||||
- `bisect.md` — The full `git bisect` procedure: manual and automated flows, exit-code semantics, skip and replay, narrowing options, and custom good/bad terms
|
||||
- `git-log-format.md` — Full `git log` format placeholder catalogue, named format presets, `--diff-filter` letters, `-L` line-range syntax, ancestry filters, pickaxe binary-file behaviour, and `git diff` output-control flags
|
||||
|
||||
68
plugins/git/skills/git-history/references/bisect.md
Normal file
68
plugins/git/skills/git-history/references/bisect.md
Normal file
@@ -0,0 +1,68 @@
|
||||
---
|
||||
topic: bisect
|
||||
source_keys:
|
||||
- git-scm-bisect-docs
|
||||
---
|
||||
|
||||
# Finding a commit with `git bisect`
|
||||
|
||||
Read this when the question is *which commit changed the behaviour* and there is no string, file,
|
||||
or line range to search the log for. Binary search reduces the trials from O(N) to O(log N).
|
||||
|
||||
## Manual flow
|
||||
|
||||
```bash
|
||||
git bisect start
|
||||
git bisect bad [HEAD] # mark current (or specified) as broken
|
||||
git bisect good <commit> # mark known-good baseline
|
||||
# Git checks out the midpoint; test it
|
||||
git bisect good # test passes
|
||||
git bisect bad # test fails
|
||||
# Repeat until git reports "X is the first bad commit"
|
||||
git bisect reset # return to the original HEAD
|
||||
```
|
||||
|
||||
## Automated
|
||||
|
||||
With a test command available, use `git bisect run <cmd>`. Git reads the exit code: `0` good,
|
||||
`1`–`124` bad, `125` skip (build broken), `126`–`127` POSIX shell errors, treated as bad, and
|
||||
`128` or above aborts the session outright rather than marking the commit bad.
|
||||
|
||||
## Untestable commits
|
||||
|
||||
`git bisect skip` excludes a commit that cannot be built or tested without deciding good or bad
|
||||
for it. When the first bad commit is adjacent to a skipped range, bisect reports that it cannot
|
||||
pinpoint the culprit and lists the candidates — that is the precise answer the skip range allows,
|
||||
not a failure.
|
||||
|
||||
## Undoing a wrong good/bad call
|
||||
|
||||
`git bisect log` prints the session's decision history. Save it, edit out the mistaken entry, and
|
||||
resume from the corrected log rather than restarting the search:
|
||||
|
||||
```bash
|
||||
git bisect log > bisect.log
|
||||
# edit bisect.log, removing the wrong decision
|
||||
git bisect reset && git bisect replay bisect.log
|
||||
```
|
||||
|
||||
## Narrowing and speeding up
|
||||
|
||||
- `git bisect start HEAD v1.2 -- src/` restricts bisection to a path, cutting the trial count.
|
||||
- `--no-checkout` updates the `BISECT_HEAD` ref instead of checking out a working tree — useful
|
||||
for tests that do not need one, and automatic in bare repos.
|
||||
- `--first-parent` follows only first parents at merges, finding the integration commit that
|
||||
introduced a regression while ignoring broken side branches.
|
||||
|
||||
## Inspecting the remaining candidates
|
||||
|
||||
`git bisect visualize` (alias `view`) opens the suspects in gitk, falling back to `git log` when
|
||||
no graphical display is detected. Add `--stat` or `-p` for a diffstat or full patches.
|
||||
|
||||
## Hunting a non-bug property change
|
||||
|
||||
`git bisect start --term-new <new> --term-old <old>` searches for any property change — a
|
||||
performance regression, say — instead of a bug. Use the custom terms in place of `good` and `bad`
|
||||
for the rest of the session.
|
||||
|
||||
Once the first bad commit is identified, return to Step 3 to act on it and Step 4 to report it.
|
||||
@@ -88,7 +88,7 @@ source_keys:
|
||||
| `%GK` | signing key ID |
|
||||
|
||||
**Trailers:**
|
||||
```
|
||||
```text
|
||||
%(trailers[:key=<k>][,only][,separator=<s>][,unfold][,keyonly][,valueonly])
|
||||
```
|
||||
|
||||
|
||||
@@ -12,7 +12,7 @@ Git bisect documentation covering binary search through commit history to find t
|
||||
|
||||
- **Research doc:** plugins/git/docs/research/docs/git/history-inspection.md
|
||||
- **Doc heading:** `## git bisect`
|
||||
- **Contributing files:** SKILL.md
|
||||
- **Contributing files:** SKILL.md, references/bisect.md
|
||||
|
||||
## git-scm-log-docs
|
||||
|
||||
@@ -28,4 +28,4 @@ Git diff documentation covering output control (--stat, --name-only, --name-stat
|
||||
|
||||
- **Research doc:** plugins/git/docs/research/docs/git/history-inspection.md
|
||||
- **Doc heading:** `## git diff — Output Control`
|
||||
- **Contributing files:** references/git-log-format.md
|
||||
- **Contributing files:** SKILL.md, references/git-log-format.md
|
||||
|
||||
Reference in New Issue
Block a user