feat: accept pull/merge request URLs in the repository field

.github/workflows/ci.yml

@@ -48,3 +48,26 @@ jobs:
 
       - name: Run Rust test suite
         run: cargo test --workspace --locked
+
+      # Runs after the Rust suite so an E2E flake cannot stop it reporting.
+      # CI uses npm's prebuilt browsers, which are fine on ubuntu; the nix
+      # devshell instead supplies pkgs.playwright-driver.browsers, because the
+      # npm builds are unpatched and will not launch on NixOS. Both paths need
+      # the browser revision to match the pinned @playwright/test version.
+      - name: Install Playwright browser
+        working-directory: crates/diffcore-tauri/ui
+        run: npx playwright install --with-deps chromium
+
+      - name: Run Playwright E2E suite
+        working-directory: crates/diffcore-tauri/ui
+        run: npx playwright test
+
+      - name: Upload Playwright report on failure
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: playwright-report
+          path: |
+            crates/diffcore-tauri/ui/playwright-report/
+            crates/diffcore-tauri/ui/test-results/
+          retention-days: 7

README.md

@@ -108,6 +108,12 @@ diffcore analyze --base main --refine --refine-model gpt-4o
 # Analyze a different repo
 diffcore analyze --base main --repo /path/to/repo
 
+# Analyze a pull/merge request by URL — clones into ~/.diffcore/cache/repos and
+# resolves base/head from the provider's PR refs. GitHub, GitLab, Gitea/Forgejo,
+# Pagure, Bitbucket Data Center, Azure DevOps and Gerrit; see
+# docs/pr-url-providers.md for URL shapes and the forges that cannot work.
+diffcore analyze --repo https://github.com/BurntSushi/ripgrep/pull/2900
+
 # Open a flow group in an external diff tool
 diffcore launch --tool bcompare --group group_1 --input review.json
 ```

TODOs.md

@@ -6,8 +6,12 @@ Replace GitHub's PR review tab entirely — do the full review in Diffcore, push
 
 ### Phase 1: GitHub Login + PR Fetching
 - GitHub OAuth login flow in Tauri app
-- `diffcore review <pr-url>` — fetch PR diff directly from GitHub API
-- Store GitHub token securely (keychain / 1Password)
+- ~~Fetch a PR diff by URL~~ — done without an API: the repository field and
+  `diffcore analyze --repo` take PR/MR URLs across forges and resolve them from
+  the provider's git refs. See [docs/pr-url-providers.md](./docs/pr-url-providers.md).
+- Store GitHub token securely (keychain / 1Password). An API token would also
+  close the gaps git refs cannot cover: Bitbucket Cloud (no PR refs at all) and
+  fast-forward-merged PRs (no recoverable base branch).
 
 ### Phase 2: Bidirectional Comment Sync
 - Push review comments from Diffcore back to GitHub as a PR review

crates/diffcore-cli/src/main.rs

@@ -26,6 +26,7 @@ use diffcore_core::llm;
 use diffcore_core::llm::refinement;
 use diffcore_core::output::{self, build_analysis_output};
 use diffcore_core::pipeline;
+use diffcore_core::pr_url;
 use diffcore_core::rank;
 use diffcore_core::types::AnalysisOutput;
 
@@ -111,7 +112,11 @@ struct AnalyzeArgs {
     #[arg(long)]
     no_cache: bool,
 
-    /// Path to the git repository (defaults to current directory)
+    /// Path to the git repository, or a pull/merge request URL
+    /// (GitHub, GitLab, Gitea/Forgejo, Pagure, Bitbucket DC, Azure DevOps, Gerrit).
+    /// URLs are cloned into ~/.diffcore/cache/repos (override with
+    /// DIFFCORE_REPO_CACHE_DIR) and resolved to base/head refs, overriding
+    /// --base/--head.
     #[arg(long, default_value = ".")]
     repo: PathBuf,
 }
@@ -316,8 +321,42 @@ fn main() {
     }
 }
 
+/// When `--repo` is a pull/merge request URL, clone (or reuse) the repository in
+/// the diffcore cache, fetch the PR refs, and rewrite `--repo`/`--base`/`--head`
+/// to point at the resolved local checkout.
+fn resolve_pr_url_args(args: &mut AnalyzeArgs) -> Result<(), Box<dyn std::error::Error>> {
+    let Some(pr) = args.repo.to_str().and_then(pr_url::parse) else {
+        return Ok(());
+    };
+    info!(
+        "Resolving {} #{} on {} ({})",
+        pr.provider.unit(),
+        pr.number,
+        pr.host,
+        pr.provider.name()
+    );
+    let resolved = pr_url::resolve(&pr)?;
+    info!("Using cached checkout at {}", resolved.path);
+    // Override rather than fill in: the resolved refs are the whole point of
+    // passing a PR URL, and a stale `--base main` would otherwise be diffed
+    // against the cached clone's own default branch and silently wrong.
+    for (flag, supplied) in [("--base", &args.base), ("--head", &args.head)] {
+        if let Some(v) = supplied {
+            warn!("ignoring {flag} {v}: refs come from {}", pr.provider.unit());
+        }
+    }
+    args.repo = PathBuf::from(&resolved.path);
+    args.base = Some(resolved.base);
+    args.head = Some(resolved.head);
+    // The checkout is detached at the PR head; never mix in working-tree state.
+    args.include_uncommitted = false;
+    args.no_include_uncommitted = true;
+    Ok(())
+}
+
 /// Run analysis and return the output (without writing or LLM steps).
-fn run_analyze_and_return(args: AnalyzeArgs) -> Result<AnalysisOutput, Box<dyn std::error::Error>> {
+fn run_analyze_and_return(mut args: AnalyzeArgs) -> Result<AnalysisOutput, Box<dyn std::error::Error>> {
+    resolve_pr_url_args(&mut args)?;
     let repo_path = std::fs::canonicalize(&args.repo)?;
     let repo =
         Repository::discover(&repo_path).map_err(|e| format!("Not a git repository: {}", e))?;
@@ -404,7 +443,8 @@ fn run_analyze_and_return(args: AnalyzeArgs) -> Result<AnalysisOutput, Box<dyn s
     Ok(analysis_output)
 }
 
-fn run_analyze(args: AnalyzeArgs) -> Result<(), Box<dyn std::error::Error>> {
+fn run_analyze(mut args: AnalyzeArgs) -> Result<(), Box<dyn std::error::Error>> {
+    resolve_pr_url_args(&mut args)?;
     // Resolve repo path
     let repo_path = std::fs::canonicalize(&args.repo)?;
     let repo =

crates/diffcore-core/Cargo.toml

@@ -17,6 +17,7 @@ tree-sitter-rust = "0.24.1"
 tree-sitter-java = "0.23.5"
 toml = "0.8"
 glob = "0.3"
+url = "2"
 reqwest = { version = "0.12", default-features = false, features = ["json", "http2", "charset", "rustls-tls-native-roots", "macos-system-configuration"] }
 tokio = { version = "1", features = ["full"] }
 async-trait = "0.1"

crates/diffcore-core/src/config.rs

@@ -490,7 +490,7 @@ impl DiffcoreConfig {
     }
 }
 
-fn diffcore_config_home() -> Option<PathBuf> {
+pub(crate) fn diffcore_config_home() -> Option<PathBuf> {
     env::var_os("DIFFCORE_CONFIG_HOME")
         .map(PathBuf::from)
         .or_else(|| env::var_os("HOME").map(|home| PathBuf::from(home).join(".diffcore")))

crates/diffcore-core/src/lib.rs

@@ -23,6 +23,7 @@ pub mod llm;
 pub mod logging;
 pub mod output;
 pub mod pipeline;
+pub mod pr_url;
 pub mod query_engine;
 pub mod manifest;
 pub mod rank;