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Merged
imfing merged 1 commit into from
Oct 6, 2026
Merged

feat(branch): compare two branches without checking either out #35

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3 changes: 2 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -43,11 +43,12 @@ diffs pr 123 # PR in the current repo
diffs pr org/repo/pull/123 # PR in any repo
```

Review the current branch against a base locally:
Review a branch against a base locally (the current branch unless a head is given):

```sh
diffs branch # infers the base
diffs branch main # explicit base
diffs branch main feature # compare two branches without checking out either
diffs branch --include-dirty # include staged, unstaged, and untracked changes
```

Expand Down
95 changes: 68 additions & 27 deletions src/cli.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,9 @@ Examples:
# Compare against an explicit base
diffs branch main

# Compare two branches without checking either out
diffs branch main feature/login

# Include uncommitted changes
diffs branch --include-dirty
";
Expand Down Expand Up @@ -157,14 +160,17 @@ enum Command {
#[command(flatten)]
serve: ServeFlags,
},
#[command(about = "Review commits on the current branch against a base")]
#[command(about = "Review commits on a branch against a base")]
#[command(after_help = BRANCH_AFTER_HELP)]
Branch {
/// Base ref to compare against (inferred from the PR or default branch when omitted)
#[arg(value_name = "BASE")]
base: Option<String>,
/// Branch to review (defaults to the checked-out branch)
#[arg(value_name = "HEAD", requires = "base")]
head: Option<String>,
/// Include staged, unstaged, and untracked changes
#[arg(long)]
#[arg(long, conflicts_with = "head")]
include_dirty: bool,
#[command(flatten)]
serve: ServeFlags,
Expand Down Expand Up @@ -257,6 +263,7 @@ pub async fn run(started: Instant) -> anyhow::Result<()> {
}
Some(Command::Branch {
base,
head,
include_dirty,
serve,
}) => {
Expand All @@ -265,7 +272,15 @@ pub async fn run(started: Instant) -> anyhow::Result<()> {
// "could not infer base ref").
resolve_repo_root_or_help(&cli.dir)?;
let base = resolve_branch_base(base, &cli.dir).await?;
let target = branch_target(&base, include_dirty);
let head = head
.map(|value| value.trim().to_string())
.filter(|value| !value.is_empty());
if let Some(head) = &head
&& !git::ref_exists(&cli.dir, head)
{
bail!("unknown head ref: {head}");
}
let target = branch_target(&base, head.as_deref(), include_dirty);
run_server_target(&cli.dir, &serve, gh_host(None), &target, true, started).await
}
Some(Command::Comments(command)) => run_comments(&cli.dir, command),
Expand Down Expand Up @@ -521,8 +536,11 @@ fn target_label(target_path: &str, cwd: &std::path::Path) -> String {
};
}
if target_path.starts_with("/branch") {
let base = branch_base_from_target(target_path);
let head = git::branch(cwd);
let base = target_query_param(target_path, "base");
let mut head = target_query_param(target_path, "head");
if head.is_empty() {
head = git::branch(cwd);
}
let head = if head.is_empty() { "HEAD" } else { &head };
return if base.is_empty() {
format!("{head} branch diff")
Expand All @@ -537,12 +555,12 @@ fn target_label(target_path: &str, cwd: &std::path::Path) -> String {
target_path.to_string()
}

fn branch_base_from_target(target_path: &str) -> String {
fn target_query_param(target_path: &str, name: &str) -> String {
let Some((_, query)) = target_path.split_once('?') else {
return String::new();
};
url::form_urlencoded::parse(query.as_bytes())
.find(|(key, _)| key == "base")
.find(|(key, _)| key == name)
.map(|(_, value)| value.into_owned())
.unwrap_or_default()
}
Expand Down Expand Up @@ -615,9 +633,12 @@ async fn resolve_branch_base(base: Option<String>, dir: &PathBuf) -> anyhow::Res
bail!("could not infer base ref; pass one explicitly, e.g. `diffs branch main`")
}

fn branch_target(base: &str, include_dirty: bool) -> String {
fn branch_target(base: &str, head: Option<&str>, include_dirty: bool) -> String {
let mut params = url::form_urlencoded::Serializer::new(String::new());
params.append_pair("base", base);
if let Some(head) = head {
params.append_pair("head", head);
}
if include_dirty {
params.append_pair("dirty", "1");
}
Expand Down Expand Up @@ -650,7 +671,7 @@ fn run_comments(dir: &PathBuf, command: CommentsCommand) -> anyhow::Result<()> {
let store = comments::Store::new(dir)?;
match command.command {
CommentSubcommand::List => {
let threads = store.list()?;
let threads = store.list(None)?;
if command.json {
print_json(&serde_json::json!({ "threads": threads }))?;
} else {
Expand All @@ -666,15 +687,18 @@ fn run_comments(dir: &PathBuf, command: CommentsCommand) -> anyhow::Result<()> {
body,
author,
} => {
let thread = store.add_thread(comments::AddThreadInput {
path,
side,
line,
end_line: end_line.unwrap_or_default(),
end_side,
body: body_from_flag(body)?,
author,
})?;
let thread = store.add_thread(
None,
comments::AddThreadInput {
path,
side,
line,
end_line: end_line.unwrap_or_default(),
end_side,
body: body_from_flag(body)?,
author,
},
)?;
print_thread_result(&thread, command.json)?;
}
CommentSubcommand::Reply {
Expand All @@ -683,6 +707,7 @@ fn run_comments(dir: &PathBuf, command: CommentsCommand) -> anyhow::Result<()> {
author,
} => {
let thread = store.add_reply(
None,
&thread_id,
comments::AddReplyInput {
body: body_from_flag(body)?,
Expand All @@ -692,11 +717,11 @@ fn run_comments(dir: &PathBuf, command: CommentsCommand) -> anyhow::Result<()> {
print_thread_result(&thread, command.json)?;
}
CommentSubcommand::Resolve { thread_id } => {
let thread = store.resolve(&thread_id)?;
let thread = store.resolve(None, &thread_id)?;
print_thread_result(&thread, command.json)?;
}
CommentSubcommand::Reopen { thread_id } => {
let thread = store.reopen(&thread_id)?;
let thread = store.reopen(None, &thread_id)?;
print_thread_result(&thread, command.json)?;
}
}
Expand Down Expand Up @@ -794,25 +819,37 @@ mod tests {
}

#[test]
fn branch_target_encodes_base_and_dirty() {
fn branch_target_encodes_base_head_and_dirty() {
assert_eq!(
branch_target("origin/main", false),
branch_target("origin/main", None, false),
"/branch?base=origin%2Fmain"
);
assert_eq!(
branch_target("origin/main", true),
branch_target("origin/main", None, true),
"/branch?base=origin%2Fmain&dirty=1"
);
assert_eq!(
branch_target("main", Some("feature/x"), false),
"/branch?base=main&head=feature%2Fx"
);
}

#[test]
fn branch_base_from_target_decodes_base() {
fn target_query_param_decodes_values() {
assert_eq!(
branch_base_from_target("/branch?base=origin%2Fmain"),
target_query_param("/branch?base=origin%2Fmain", "base"),
"origin/main"
);
assert_eq!(branch_base_from_target("/branch?base=main&dirty=1"), "main");
assert_eq!(branch_base_from_target("/local"), "");
assert_eq!(
target_query_param("/branch?base=main&dirty=1", "base"),
"main"
);
assert_eq!(
target_query_param("/branch?base=main&head=feature%2Fx", "head"),
"feature/x"
);
assert_eq!(target_query_param("/branch?base=main", "head"), "");
assert_eq!(target_query_param("/local", "base"), "");
}

#[test]
Expand All @@ -832,6 +869,10 @@ mod tests {
target_label("/branch?base=origin%2Fmain", dir.path()),
"feature/startup -> origin/main"
);
assert_eq!(
target_label("/branch?base=main&head=other", dir.path()),
"other -> main"
);
assert_eq!(
target_label("/org/repo/pull/123", dir.path()),
"GitHub PR org/repo#123"
Expand Down
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