---
name: isurus-conventions
description: Use when working in the Isurus repository (or any repo identified as Isurus by the presence of `Isurus` in `README.md` or `cmd/isurus/`). Encodes Isurus-specific Mercurial conventions: non-publishing repo, bookmarks-as-PRs, commit message style, pre-PR Makefile checklist, opening PRs in the Isurus web UI.
---

# Isurus conventions (Mercurial overlay)

## When this applies

Use when working in the Isurus repository. Detect Isurus by:
- Repo root contains `cmd/isurus/`, or
- Top-level `README.md` contains the word `Isurus`, or
- Repo is cloned from `ssh://hg@hg.leafscale.com/leafscale/isurus`.

This skill is **purely additive**. The procedures live in `mercurial-basics`, `mercurial-bookmarks-and-prs`, `mercurial-sync-and-merge`, `mercurial-history-rewriting`, and `mercurial-finishing-a-branch`. This file supplies Isurus-specific values those procedures plug into.

## Repository facts

| Fact | Value |
|---|---|
| VCS | Mercurial 7.x (never git) |
| Clone URL | `ssh://hg@hg.leafscale.com/leafscale/isurus` |
| Long-lived branches | `default`, `stable` |
| Phase model | **Non-publishing** — pushed changesets stay `draft` until merged |
| Feature/PR mechanism | **Bookmarks** (push with `-B <name>`) |
| Forge | Isurus (web UI at `https://hg.leafscale.com/`) |

## Commit messages in this repo

- Imperative summary, **under 72 characters**.
- Prefix with a category: `feat:`, `fix:`, `chore:`, `docs:`, `test:`, `refactor:`, `scripts:`, `hgignore:`. Match what `hg log` shows for recent commits if uncertain.
- Body (optional) explains *why*; the diff shows *what*.
- One blank line between summary and body.
- **Never pass `-u`** to `hg commit` — identity is in `~/.hgrc`.

## Pre-PR check sequence

Run from the repo root, in this order:

```sh
make fmt        # gofmt — leaves no diff if all files are formatted
make vet        # go vet — catches suspicious constructs
make check      # full test suite against PostgreSQL test DB
```

`make check` requires the `isurus-test` database on localhost:
- DB name: `isurus-test`
- User: `isurus-test`
- Password: `isurus-test`

Override with `ISURUS_TEST_DSN`. See `make test-setup` for one-time DB creation.

Optional but recommended (skip if not installed):

```sh
make lint       # golangci-lint
```

The PR checklist from `CONTRIBUTING.md` (must all be true before opening PR):

- `make check` passes
- `go vet ./...` is clean
- Code is formatted (`make fmt`)
- New public functions have short godoc comments where non-obvious
- No new `TODO`/`FIXME` markers (fix or file an issue instead)
- Documentation updated if behavior or configuration changed
- Commit messages explain *why*

## Pull request flow

1. `hg push -B <bookmark>` to the canonical remote.
2. Open a PR in the Isurus web UI (`https://hg.leafscale.com/<owner>/<repo>`).
3. Title: same as the commit message summary.
4. Description: *why* + link to related issues.
5. Reviewer feedback → `hg amend` → `hg push -B <bookmark> -f`.

The non-publishing repo makes `-f` after amend the **expected** workflow, not a sign of trouble.

## What this overlay does NOT cover

- General Mercurial commands → `mercurial-basics`.
- Bookmark mechanics → `mercurial-bookmarks-and-prs`.
- Pull / merge / conflicts → `mercurial-sync-and-merge`.
- Amend / uncommit / phase rules → `mercurial-history-rewriting`.
- The end-to-end "finish a branch" sequence → `mercurial-finishing-a-branch`.

This file only changes the *values* those skills use (URLs, branch names, check commands). The procedures stay the same.
---
name: mercurial-basics
description: Use when working in any Mercurial repository for inspection or local commits — `hg status`, `diff`, `log`, `add`, `commit`, `parents`, `heads`, `branches`, `bookmarks`, `phase`. Triggers on any `hg ...` command or when `.hg/` is in the working directory.
---

# Mercurial basics

## When this applies

Use when:
- The working directory contains `.hg/` (or any ancestor does).
- About to run any `hg` command.
- About to perform an operation that has both git and hg equivalents and the repo is hg.

Do not use for:
- Pulling, merging, conflict resolution → see `mercurial-sync-and-merge`.
- Bookmarks and the PR workflow → see `mercurial-bookmarks-and-prs`.
- Amending or rewriting history → see `mercurial-history-rewriting`.

## Identity comes from ~/.hgrc

**Never pass `-u` to `hg commit`.** Identity is configured globally in `~/.hgrc`:

```ini
[ui]
username = Name <email@example.com>
```

`hg commit -u "..."` is for impersonation and will create commits with the wrong author. Always:

```sh
hg commit -m "your message"
```

## Inspection commands

| Need | Command |
|---|---|
| What changed in working dir | `hg status` |
| Diff of unstaged changes | `hg diff` |
| Recent commits | `hg log` (or `hg log -l 10` for limit) |
| Working dir parent revision | `hg parents` |
| All current heads | `hg heads` |
| Named branches | `hg branches` |
| Bookmarks (≈ feature branches) | `hg bookmarks` |
| Phase of a revision | `hg phase -r <rev>` |
| Who wrote each line | `hg annotate <file>` (git users: `blame`) |

## Reading `hg log` output

Default format shows changeset hash, branch (if not `default`), tag, user, date, and summary:

```
changeset:   42:a1b2c3d4e5f6
branch:      myfeature
tag:         tip
bookmark:    work-in-progress
user:        Alice <alice@example.com>
date:        Mon May 02 09:00:00 2026 -0500
summary:     feat: add the thing
```

For terser output: `hg log --template '{node|short} {bookmarks} {branch} {desc|firstline}\n'`

## Commit messages

The Isurus convention (and a generally good rule) is:

- **First line:** imperative summary, **under 72 characters**. Examples: `feat: add language stats to repo sidebar`, `fix: handle nil reviewer in PR template`, `chore: bump dependency X to v2`.
- **Body (optional):** explain *why* the change is being made. The diff already shows *what*. One blank line between summary and body.
- **Category prefix** (`feat:`, `fix:`, `docs:`, `chore:`, `test:`, `refactor:`) is convention in this codebase — match what `hg log` shows.

Keep each commit focused. If a single change touches unrelated areas, split into separate commits.

## Adding files

```sh
hg add path/to/file       # explicit
hg add                    # add all untracked files (use carefully)
```

Mercurial does not have a staging area. Files are tracked or not; commits include all changes to tracked files. To commit only some changes, use `hg commit path/to/file1 path/to/file2`.

## .hgignore syntax

`.hgignore` lives at the repo root. Default syntax is `glob`:

```
syntax: glob

# Build artifacts
dist/
*.o

# Switch syntax for a section
syntax: rootglob
binary-at-root-only

# Switch back
syntax: glob
**/*.swp
```

`syntax: rootglob` matches only at the repo root (useful for binary names that must not match files in subdirectories).

## Phase awareness

Every changeset has a phase: `draft`, `public`, or `secret`. The phase governs what's safe to rewrite:

- **draft** — local or pushed-but-not-merged. Safe to amend, uncommit, rewrite.
- **public** — published and considered immutable.
- **secret** — never pushed.

In a non-publishing repo (like Isurus), pushed changesets stay draft until merged into the canonical branch. This is what makes `hg amend` safe during code review. See `mercurial-history-rewriting` for the rewriting rules.

To check: `hg phase -r <rev>`. To see your tip: `hg phase -r tip`.

## Common workflow examples

Inspect what's changed and commit:

```sh
hg status
hg diff
hg add new-file.go
hg commit -m "feat: add new thing"
```

See recent history on a bookmark:

```sh
hg log -l 5 -B my-feature
```

Diff between two revisions:

```sh
hg diff -r REV1 -r REV2
```
---
name: mercurial-bookmarks-and-prs
description: Use when starting feature work, switching between in-progress work, or pushing a feature for review in a Mercurial repo. Bookmarks are the unit of feature work and the unit of pull requests in this workflow.
---

# Mercurial bookmarks and pull requests

## When this applies

Use when:
- Starting a new feature or fix that will become a pull request.
- Switching between multiple in-progress features.
- About to push work for review.
- A bookmark is in the wrong place and needs fixing.

Do not use for:
- Long-lived branches like `default`, `stable` — those are named branches, see "Bookmark vs named branch" below for the distinction.
- Pulling/merging upstream changes → see `mercurial-sync-and-merge`.
- Amending commits before push → see `mercurial-history-rewriting`.

## Bookmark vs named branch

| | Bookmark | Named branch |
|---|---|---|
| Purpose | Feature/PR pointer | Long-lived line of development |
| Lifetime | Days to weeks; deleted after merge | Months to years |
| Examples | `add-language-stats`, `fix-nil-reviewer` | `default`, `stable`, `release-2.0` |
| Moves on commit? | Yes (the active one moves) | The new commit stays on the branch |
| Can be deleted? | Yes (`hg bookmark -d`) | Effectively no |

**Rule of thumb:** if you'd open a PR for it, it's a bookmark. If it's a maintained release line, it's a named branch.

### When the user says "branch"

Most users come to Mercurial from Git, where "branch" means a lightweight pointer that can be deleted. In Mercurial that concept is a **bookmark**, not a named branch. Map their words accordingly:

- **"create a feature branch", "start a branch", "switch branches", "branch off X"** → bookmark, every time.
- **"create a release branch", "branch for v2.0"** → named branch (long-lived release line).
- **Ambiguous** → ask, but default to bookmark for anything PR-shaped.

**Override repo precedent.** If you find existing named branches that look like feature work (e.g. an `add-language-stats` named branch alongside `default`), do *not* infer that the convention is to use named branches. That precedent is almost always a previous mistake (often by an LLM that didn't load this skill). Use a bookmark for the new work and surface the inconsistency:

> "Heads up: this repo has named branches (`add-language-stats`, `fix-nil-reviewer`) that look like feature work, which is unusual — feature work in Mercurial is typically a bookmark. I'm using a bookmark for the new feature; let me know if you'd prefer to match the existing pattern."

The only time existing named branches *should* steer you toward a named branch is when they are clearly long-lived release lines (`stable`, `release-1.0`, `release-2.0`).

## Starting a feature

```sh
hg pull -u                  # sync to latest default
hg bookmark my-feature      # create bookmark at current rev
# ... edit files ...
hg add new-file.go
hg commit -m "feat: add new thing"
hg push -B my-feature       # push the bookmark to the remote
```

After `hg commit`, the bookmark `my-feature` advances to the new changeset automatically (it's the active bookmark).

## Listing bookmarks

```sh
hg bookmarks
```

Output marks the active bookmark with `*`:

```
   add-language-stats        42:a1b2c3d4e5f6
 * my-feature                47:b9c8d7e6f5a4
   work-in-progress          39:c5d4e3f2a1b0
```

## Switching bookmarks

```sh
hg update my-feature        # switch to the bookmark and make it active
```

`hg update` checks out the changeset the bookmark points to AND activates the bookmark (so future commits move it forward).

If you only want to look at a revision without activating any bookmark there:

```sh
hg update -r <revision>
```

## Pushing for review

The Isurus convention (non-publishing repo + bookmarks = PRs):

```sh
hg push -B my-feature
```

`-B my-feature` pushes the bookmark by name. Without `-B`, `hg push` pushes the current head's changesets but does not push the bookmark itself, which means the remote won't know to associate them with a PR.

After pushing, open the PR in the Isurus web UI (or the equivalent forge UI). See `isurus-conventions` for Isurus specifics.

## Updating a PR after review feedback

In a non-publishing repo, pushed changesets stay `draft` until the PR is merged. That means amending after a push is **safe**:

```sh
# ... make the requested changes ...
hg amend                    # rewrites the tip changeset in place
hg push -B my-feature -f    # -f because the rewrite changed the hash
```

The `-f` is required because the new amended changeset has a different hash than what's on the remote; without `-f` the push is rejected. This is the *intended* workflow — not a sign you're doing something dangerous, because the changesets are still draft.

## Deleting a bookmark after merge

Once the PR is merged into `default`:

```sh
hg pull -u                  # pull in the merged changes
hg bookmark -d my-feature   # delete locally
hg push --delete my-feature # delete on the remote (if not already gone)
```

## Recovering a misplaced bookmark

If the bookmark is on the wrong changeset (e.g., you forgot it was active and committed something unrelated):

```sh
hg bookmarks                          # see where it is
hg bookmark my-feature -r <correct>   # move it
```

The `-r` flag moves an existing bookmark to a specific revision without checking out anything.

## Common pitfalls

- **Forgetting `-B` on push:** the changesets land but no bookmark = no PR association. Re-push with `hg push -B <name>`.
- **Forgetting `-f` after amend:** push is rejected with "remote has changesets you don't have." Verify it's your own amended changeset (not a real upstream change), then `-f`.
- **Active bookmark surprise:** `hg update -r <rev>` *without* a bookmark name leaves no bookmark active; subsequent commits create anonymous heads. Always activate a bookmark you intend to commit to.
---
name: mercurial-finishing-a-branch
description: Use when an implementation is complete and ready to be proposed as a pull request — runs the pre-PR checklist (build, vet, format, test) and walks through pushing the bookmark and opening a PR. The Mercurial counterpart to superpowers' `finishing-a-development-branch`.
---

# Mercurial: finishing a development branch

## When this applies

Use when:
- Implementation is complete and the user is ready to propose a PR.
- The user says "let's ship this" / "this is done" / "let's open a PR" in an hg repo.

Do not use for:
- Mid-development commits → see `mercurial-basics`.
- Recovering from a bad commit → see `mercurial-history-rewriting`.

## The flow

Six steps. Do them in order; do not skip.

### 1. Verify the working directory is clean

```sh
hg status
```

Expected: empty output. If anything is shown:
- New files you intended to include → `hg add` and amend the tip commit.
- New files you didn't mean to track → add to `.hgignore` and commit that change separately.
- Modified files → either amend or commit them as a separate change.

Do not push with uncommitted changes lingering.

### 2. Verify you're on the right bookmark

```sh
hg bookmarks
```

The active bookmark is marked with `*`. Confirm it's the feature bookmark, not e.g. an accidental commit on no bookmark.

If a feature bookmark exists but isn't active:

```sh
hg update <bookmark-name>
```

If commits were made without an active bookmark (anonymous head):

```sh
hg bookmark <feature-name> -r .
```

(See `mercurial-bookmarks-and-prs` for the bookmark mechanics.)

### 3. Verify history is clean

```sh
hg log -l 10 --template '{node|short} {phase} {desc|firstline}\n'
```

Look for:
- All commits should be `draft` (in non-publishing repos like Isurus).
- Commit messages follow the convention (imperative summary, <72 chars, "category: summary" prefix where the project uses one).
- No "wip", "fix typo", "address review" debris — squash via `hg amend` / `hg uncommit`.

If cleanup is needed → see `mercurial-history-rewriting`. The non-publishing repo means amend is safe even on already-pushed changesets.

### 4. Run the project's pre-PR checks

Detect the project's check command:

```sh
ls Makefile 2>/dev/null && grep -E '^(check|test|fmt|vet|lint):' Makefile
```

Common patterns:
- **Has `Makefile` with `check` target:** `make check` (full test suite). Then run `make fmt` and `make vet` if those exist.
- **Go project, no Makefile:** `go test ./...`, `go vet ./...`, `gofmt -l .` (anything output = unformatted).
- **Other languages:** match the project's documented test/lint commands.

For the Isurus repository specifically, see `isurus-conventions` — it documents the exact `make` targets used.

If checks fail, **fix or surface** before continuing. Do not push code that fails the project's own gate.

### 5. Push the bookmark

```sh
hg push -B <bookmark-name>
```

The `-B <bookmark-name>` is critical — without it the changesets push but the remote doesn't know to associate them with a bookmark/PR.

If the push is rejected because the bookmark was previously pushed and has since been amended:

```sh
hg push -B <bookmark-name> -f
```

`-f` is the expected workflow in non-publishing repos after `hg amend`. See `mercurial-bookmarks-and-prs` for context.

### 6. Open the pull request

In the forge web UI:
1. Navigate to the repository.
2. The forge typically shows a banner offering to open a PR for the just-pushed bookmark — click it.
3. Title the PR using the same format as the commit message summary.
4. PR description: explain *why*, link any related issues. The diff shows *what*; don't repeat it in the description.

For Isurus-specific URL patterns and PR conventions → see `isurus-conventions`.

## After the PR is open

When reviewer feedback comes in:
- Make the requested changes locally.
- `hg amend` to fold the fix into the existing changeset (in non-publishing repos).
- `hg push -B <bookmark-name> -f`.
- Reply to the review comments confirming the fix is pushed.

When the PR is merged:
- `hg pull -u` to bring the merged changes locally.
- `hg bookmark -d <bookmark-name>` to delete the local bookmark.
- Optionally `hg push --delete <bookmark-name>` if the forge doesn't auto-delete on merge.
---
name: mercurial-history-rewriting
description: Use when rewriting Mercurial history — amending commits, uncommitting, splitting commits, or recovering from a mistake. Critical: only safe on draft changesets, never on public ones.
---

# Mercurial history rewriting

## When this applies

Use when:
- About to amend a commit (fix typo, add forgotten file, edit the message).
- Need to uncommit / split a changeset.
- Recovering from a mistaken commit.

Do not use for:
- Routine commits → see `mercurial-basics`.
- Bookmark/PR push flow → see `mercurial-bookmarks-and-prs`.
- Conflicts after merging → see `mercurial-sync-and-merge`.

## The fundamental rule: draft only

**Only rewrite changesets in `draft` phase. Never rewrite `public` ones.**

Check before rewriting:

```sh
hg phase -r tip                 # or any specific revision
```

If the phase is `public`, **stop and surface the situation to the user.** Rewriting public history breaks every other clone of the repo. Mercurial will refuse by default with: `cannot amend public changesets`.

In Isurus the repo is non-publishing, so pushed changesets stay `draft` until merged into the canonical branch. That makes `hg amend` safe during code review. After merge, the changesets become `public` and are off-limits.

## `hg amend` — fix the tip changeset in place

The most common rewrite. Edit files, then:

```sh
hg amend                        # fold working-dir changes into tip; keeps message
hg amend -m "new message"       # also rewrite the message
hg amend file1 file2            # only fold those files
```

After amend, the new changeset has a different hash. If it was already pushed, you'll need `-f` next push:

```sh
hg push -B my-feature -f
```

This is normal in a non-publishing repo. See `mercurial-bookmarks-and-prs` for the post-amend push pattern.

## `hg uncommit` — undo a commit, keeping changes in working dir

```sh
hg uncommit                     # the entire tip changeset
hg uncommit file1 file2         # only those files (rest stay committed)
```

Use cases:
- The commit message is wrong and you want to redo it from scratch.
- You committed too much and want to split.

After uncommit, the files are back in the working dir as uncommitted changes. Re-commit selectively.

## Splitting a commit

Goal: turn one commit into two (or more) more focused ones.

```sh
hg uncommit                                # uncommit everything
hg commit path/to/group-1 -m "feat: part 1"
hg commit path/to/group-2 -m "feat: part 2"
```

If groups overlap by line within a single file, you may need to use a partial-add tool — that's beyond v1 scope. Manually patch and recommit, or use `hg commit -i` (interactive) if available.

## Recovering from a mistake

### "I committed too soon / wrong message"

```sh
hg amend -m "the right message"
```

### "I committed to the wrong bookmark"

```sh
hg bookmarks                            # see what's where
hg bookmark wrong-name -r .~1           # move the wrong bookmark back one
hg bookmark right-name -r .             # put the right bookmark on tip
```

### "I committed something I shouldn't have"

If only the most recent commit is wrong and changes haven't been pushed:

```sh
hg uncommit                             # changes return to working dir
# discard them (CAREFUL — destructive):
hg revert --all --no-backup             # discard all working-dir changes
```

### "I want to undo the last several local commits"

This is harder in vanilla Mercurial without `evolve`. Options:

1. `hg strip <rev>` — removes a changeset and all descendants. Requires the `strip` extension (`[extensions] strip = ` in `~/.hgrc`). Destructive; backups are saved in `.hg/strip-backup/` by default.
2. Re-clone from the remote, lose local changes.

In Isurus today, prefer option 1 with the strip extension. For complex multi-commit rewrites, this is exactly the case where `evolve` + `topics` would help (deferred to phase 2).

## What `hg rollback` is and isn't

`hg rollback` undoes the most recent transaction (commit, pull, push). It's mostly deprecated because it operates on the *transaction*, not the changeset, and quietly loses information. **Prefer `hg amend` / `hg uncommit` / `hg strip` instead.** The repo's `[ui] rollback = false` is recommended (and is the default in modern Mercurial).

## Public-changeset attempts

If an `hg amend` returns:

```
abort: cannot amend public changesets: <hash>
```

Do not use `--force` to override. Stop and surface the situation: someone (or the workflow) has marked this changeset public, which means it's been integrated. The right answer is a *new* commit on top, not a rewrite.

## A note on evolve / topics

Modern Mercurial (with the `evolve` extension and `topics`) supports rich history rewriting workflows: stable obsolescence markers, topic branches, automatic descendant rebasing. Isurus does not enable these today; if it does in a future version, this skill will grow a sibling (`mercurial-evolve`) or be expanded.
---
name: mercurial-sync-and-merge
description: Use when pulling changes from a remote, updating to a different revision, dealing with multiple heads, or resolving merge conflicts in a Mercurial repo.
---

# Mercurial sync and merge

## When this applies

Use when:
- Pulling changes from a remote.
- Updating the working directory to a different revision.
- The repo has multiple heads on the same branch.
- Resolving merge conflicts.

Do not use for:
- Local commit hygiene → see `mercurial-basics`.
- Moving or deleting bookmarks → see `mercurial-bookmarks-and-prs`.
- Amending after a merge → see `mercurial-history-rewriting`.

## Pull then update

```sh
hg pull         # fetch new changesets, do not touch the working dir
hg update       # update working dir to tip of the active branch/bookmark
```

Combined:

```sh
hg pull -u      # pull then update in one step (most common)
```

If a pull brings in changesets that create a new head on the same branch (someone else committed in parallel), `hg update` will move to the new tip *only if* the working dir is at the previous tip. Otherwise it warns about multiple heads.

## Multiple heads

A "head" is a changeset with no children on the same branch. Normal repos have one head per branch. Two parallel commits → two heads.

See them:

```sh
hg heads                       # all heads
hg heads default               # heads on the default branch
```

Resolution options:

1. **Merge them** — combine the two lines:

   ```sh
   hg update -r <head A>
   hg merge <head B>
   # resolve any conflicts (see below)
   hg commit -m "merge: combine parallel work"
   ```

2. **Rebase your work onto the other head** (preferred for personal feature work):

   ```sh
   # If your work is the new head and the other is upstream:
   hg update -r <upstream head>
   # then for each of your local commits, replay using rebase or amend
   ```

   Note: vanilla Mercurial without the `rebase` extension can't `hg rebase` directly. Either enable `rebase` in `~/.hgrc` (`[extensions] rebase = `) or fall back to merge.

For Isurus today: merge is the safe default; rebase is not part of the v1 workflow.

## Merging two heads

```sh
hg update -r <target>                              # check out the changeset to merge INTO
hg merge -r <source> --tool internal:merge        # bring source into the working dir
# files with conflicts are listed in the output
```

**Always pass `--tool internal:merge`** when running `hg merge` from a Claude Code session. The user's `~/.hgrc` may default to `vimdiff`, `kdiff3`, or another interactive tool, none of which work in a non-TTY context — the merge will hang or error. `internal:merge` writes conflict markers (`<<<<<<<` / `=======` / `>>>>>>>`) into the file and returns control immediately, which is exactly what the resolution flow below assumes.

## Conflict resolution

After `hg merge`, files in conflict are marked. Inspect them:

```sh
hg resolve --list              # 'U' = unresolved, 'R' = resolved
```

Edit each unresolved file. Conflict markers look like:

```
<<<<<<< local
your version
=======
their version
>>>>>>> other
```

Remove the markers, keep the correct content, save. Then mark resolved:

```sh
hg resolve --mark path/to/file
```

Or after editing all of them:

```sh
hg resolve --mark --all
```

Verify nothing remains:

```sh
hg resolve --list              # should print nothing
```

Re-run a merge tool on a specific file (e.g., to retry):

```sh
hg resolve --tool internal:merge3 path/to/file
```

### Shortcuts when one side wins

If the user explicitly picks one side ("keep ours", "take theirs") rather than wanting a hand-merge, use the appropriate `internal:` resolver — it both resolves and marks in one step, no manual editing needed:

```sh
hg resolve --tool internal:local path/to/file     # keep working-dir version
hg resolve --tool internal:other path/to/file     # take incoming version
```

Then verify with `hg resolve --list` and proceed to commit.

Once all files are resolved:

```sh
hg commit -m "merge: combine X and Y"
```

A merge commit has two parents. `hg log --graph` (or `hg log -G`) shows the merge visually.

## Aborting a merge

If you started a merge and want to back out:

```sh
hg update -C -r <pre-merge revision>
```

`-C` means clean — discard the in-progress merge state. Verify the working dir is clean afterward with `hg status`.

## Common pitfalls

- **`hg pull` without `-u`:** changesets are in the repo but the working dir is unchanged. You're working against stale code without realizing.
- **Two parents after merge with no commit:** if you `hg merge` and then run other commands, the working dir has two parents until you `hg commit`. Until then, `hg parents` shows both.
- **Conflict markers committed:** if you `hg commit` without removing all `<<<<<<<`/`=======`/`>>>>>>>` markers, you commit broken files. Always grep before commit:

  ```sh
  grep -r '<<<<<<<' .
  ```