g1t/crates/runner/src/update.rs
| 1 | //! Brings a pull request up to date with the branch it would merge into. |
| 2 | //! |
| 3 | //! When that branch has moved, the pull request cannot merge until it holds |
| 4 | //! the new commits. This merges them in. If the merge is clean that is all; |
| 5 | //! if it conflicts, the agent is given the conflicted files and what the |
| 6 | //! pull request is for, and resolves them. Either way the result is pushed |
| 7 | //! and everything done is recorded in the pull request's session. |
| 8 | //! |
| 9 | //! Configuration, beyond what a session needs (see `main`): |
| 10 | //! |
| 11 | //! - `GIT_REMOTE`, `GIT_BRANCH`: the pull request's source. |
| 12 | //! - `UPSTREAM_REMOTE`, `UPSTREAM_BRANCH`: what it would merge into. |
| 13 | //! - `PROMPT`: what the pull request is for, given to the agent on a conflict. |
| 14 | |
| 15 | use std::path::Path; |
| 16 | use std::process::Command; |
| 17 | |
| 18 | use anyhow::{Context, Result, bail}; |
| 19 | |
| 20 | use crate::report::{Entry, Reporter}; |
| 21 | use crate::{WORKDIR, auth_option, env, git, harness}; |
| 22 | |
| 23 | /// Runs git and says whether it succeeded, for commands whose failure is |
| 24 | /// an answer and not an error. |
| 25 | fn git_ok(dir: &Path, args: &[&str]) -> bool { |
| 26 | Command::new("git") |
| 27 | .current_dir(dir) |
| 28 | .args(args) |
| 29 | .output() |
| 30 | .is_ok_and(|output| output.status.success()) |
| 31 | } |
| 32 | |
| 33 | fn short(commit: &str) -> &str { |
| 34 | &commit[..commit.len().min(12)] |
| 35 | } |
| 36 | |
| 37 | /// The files a stopped merge left in conflict. |
| 38 | fn conflicted(workdir: &Path) -> Result<Vec<String>> { |
| 39 | Ok(git(workdir, &["diff", "--name-only", "--diff-filter=U"])? |
| 40 | .lines() |
| 41 | .map(str::to_owned) |
| 42 | .collect()) |
| 43 | } |
| 44 | |
| 45 | /// Whether a file still holds the markers git writes around a conflict. |
| 46 | fn has_markers(workdir: &Path, file: &str) -> bool { |
| 47 | std::fs::read_to_string(workdir.join(file)).is_ok_and(|text| { |
| 48 | text.lines() |
| 49 | .any(|line| line.starts_with("<<<<<<< ") || line.starts_with(">>>>>>> ")) |
| 50 | }) |
| 51 | } |
| 52 | |
| 53 | fn update(reporter: &mut Reporter) -> Result<()> { |
| 54 | let remote = env("GIT_REMOTE")?; |
| 55 | let branch = env("GIT_BRANCH")?; |
| 56 | let upstream = env("UPSTREAM_REMOTE")?; |
| 57 | let upstream_branch = env("UPSTREAM_BRANCH")?; |
| 58 | let auth = auth_option(&env("G1T_USER")?, &env("G1T_TOKEN")?); |
| 59 | let workdir = Path::new(WORKDIR); |
| 60 | |
| 61 | std::fs::create_dir_all("/work")?; |
| 62 | crate::clone::clone(Path::new("/work"), &auth, &["--branch", &branch], &remote, WORKDIR).context("could not clone the pull request")?; |
| 63 | git(workdir, &["config", "user.name", crate::AUTHOR_NAME])?; |
| 64 | git(workdir, &["config", "user.email", crate::AUTHOR_EMAIL])?; |
| 65 | crate::clone::fetch(workdir, &auth, &upstream, &upstream_branch).with_context(|| format!("could not fetch {upstream_branch}"))?; |
| 66 | // Shallow: deep enough to tell whether it is behind, and to merge. |
| 67 | crate::clone::share_history(workdir, &auth, &[("origin", branch.as_str()), (upstream.as_str(), upstream_branch.as_str())], "HEAD", "FETCH_HEAD")?; |
| 68 | let theirs = git(workdir, &["rev-parse", "FETCH_HEAD"])?; |
| 69 | |
| 70 | if git_ok( |
| 71 | workdir, |
| 72 | &["merge-base", "--is-ancestor", "FETCH_HEAD", "HEAD"], |
| 73 | ) { |
| 74 | reporter.record(Entry::new( |
| 75 | "note", |
| 76 | &format!("Already up to date with {upstream_branch}."), |
| 77 | )); |
| 78 | return Ok(()); |
| 79 | } |
| 80 | reporter.record(Entry::new( |
| 81 | "note", |
| 82 | &format!( |
| 83 | "{upstream_branch} has moved to {}. Merging it into this pull request.", |
| 84 | short(&theirs) |
| 85 | ), |
| 86 | )); |
| 87 | reporter.flush(); |
| 88 | |
| 89 | let message = format!("Catch up with {upstream_branch}"); |
| 90 | if !git_ok( |
| 91 | workdir, |
| 92 | &["merge", "--no-edit", "-m", &message, "FETCH_HEAD"], |
| 93 | ) { |
| 94 | let files = conflicted(workdir)?; |
| 95 | if files.is_empty() { |
| 96 | bail!("the merge failed for a reason other than a conflict"); |
| 97 | } |
| 98 | reporter.record(Entry::new( |
| 99 | "note", |
| 100 | &format!("The merge conflicts in: {}.", files.join(", ")), |
| 101 | )); |
| 102 | let prompt = format!( |
| 103 | "You are a coding agent working in the git repository checked out in the current directory.\n\n\ |
| 104 | A merge of `{upstream_branch}` into this pull request's branch has stopped with conflicts in:\n{}\n\n\ |
| 105 | What this pull request is for:\n\n{}\n\n\ |
| 106 | Resolve every conflict so that the result keeps what `{upstream_branch}` changed and what this pull request set out to do. \ |
| 107 | Read both sides before choosing; do not simply take one. Remove all conflict markers. \ |
| 108 | If the project has tests, run them. Then stage the files with `git add`. Do not commit and do not push; that is done for you. \ |
| 109 | Finish with one or two sentences on how you resolved each conflict.", |
| 110 | files |
| 111 | .iter() |
| 112 | .map(|file| format!("- {file}")) |
| 113 | .collect::<Vec<_>>() |
| 114 | .join("\n"), |
| 115 | std::env::var("PROMPT").unwrap_or_default(), |
| 116 | ); |
| 117 | reporter.record(Entry::new("prompt", &prompt)); |
| 118 | reporter.flush(); |
| 119 | let summary = harness::run_claude(workdir, &prompt, reporter)?; |
| 120 | reporter.record(Entry::new("message", &summary)); |
| 121 | |
| 122 | git(workdir, &["add", "--all"])?; |
| 123 | let unresolved = conflicted(workdir)?; |
| 124 | if !unresolved.is_empty() || files.iter().any(|file| has_markers(workdir, file)) { |
| 125 | bail!("conflicts remain after the agent's attempt to resolve them"); |
| 126 | } |
| 127 | git(workdir, &["commit", "--quiet", "--no-edit"]) |
| 128 | .context("could not conclude the merge")?; |
| 129 | reporter.record(Entry::new( |
| 130 | "note", |
| 131 | &format!("Resolved the conflicts in {}.", files.join(", ")), |
| 132 | )); |
| 133 | } |
| 134 | |
| 135 | let head = git(workdir, &["rev-parse", "HEAD"])?; |
| 136 | git( |
| 137 | workdir, |
| 138 | &[ |
| 139 | "-c", |
| 140 | &auth, |
| 141 | "push", |
| 142 | "--quiet", |
| 143 | "origin", |
| 144 | &format!("HEAD:{branch}"), |
| 145 | ], |
| 146 | ) |
| 147 | .context("could not push the updated pull request")?; |
| 148 | reporter.record(Entry::new( |
| 149 | "note", |
| 150 | &format!( |
| 151 | "Pushed {}. This pull request now contains {upstream_branch}.", |
| 152 | short(&head) |
| 153 | ), |
| 154 | )); |
| 155 | Ok(()) |
| 156 | } |
| 157 | |
| 158 | pub fn main() -> i32 { |
| 159 | let mut reporter = match Reporter::from_env() { |
| 160 | Ok(reporter) => reporter, |
| 161 | Err(error) => { |
| 162 | eprintln!("g1t-runner: {error:#}"); |
| 163 | return 2; |
| 164 | } |
| 165 | }; |
| 166 | let outcome = update(&mut reporter); |
| 167 | if let Err(error) = &outcome { |
| 168 | eprintln!("g1t-runner: {error:#}"); |
| 169 | reporter.record(Entry::new( |
| 170 | "note", |
| 171 | &format!("Catching up failed: {error:#}. Nothing was pushed."), |
| 172 | )); |
| 173 | } |
| 174 | reporter.flush(); |
| 175 | i32::from(outcome.is_err()) |
| 176 | } |