feat(build): Auto-detect base_ref from git merge-base

Add automatic detection of base reference for build uploads by finding
the merge-base between current HEAD and remote tracking branch.

This works by:

- Finding the remote tracking branch (origin/HEAD, main, master, develop)
- Calculating git merge-base between HEAD and remote branch
- Returning the branch name pointing to merge-base or commit SHA

This mirrors the existing head_ref auto-detection behavior.

Author: runningcode

src/commands/build/upload.rs

@@ -24,7 +24,8 @@ use crate::utils::fs::TempDir;
 use crate::utils::fs::TempFile;
 use crate::utils::progress::ProgressBar;
 use crate::utils::vcs::{
-    self, get_provider_from_remote, get_repo_from_remote, git_repo_head_ref, git_repo_remote_url,
+    self, get_provider_from_remote, get_repo_from_remote, git_repo_base_ref, git_repo_head_ref,
+    git_repo_remote_url,
 };
 
 pub fn make_command(command: Command) -> Command {
@@ -79,7 +80,7 @@ pub fn make_command(command: Command) -> Command {
         .arg(
             Arg::new("base_ref")
                 .long("base-ref")
-                .help("The reference (branch) to use for the upload. If not provided, the current reference will be used.")
+                .help("The base reference (branch) to use for the upload. If not provided, the merge-base with the remote tracking branch will be used.")
         )
         .arg(
             Arg::new("pr_number")
@@ -172,7 +173,28 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
 
     let base_repo_name = matches.get_one("base_repo_name").map(String::as_str);
     let base_sha = matches.get_one("base_sha").map(String::as_str);
-    let base_ref = matches.get_one("base_ref").map(String::as_str);
+    let base_ref = matches
+        .get_one("base_ref")
+        .map(String::as_str)
+        .map(Cow::Borrowed)
+        .or_else(|| {
+            // Try to get the base ref from the VCS if not provided
+            // This attempts to find the merge-base with the remote tracking branch
+            if let Ok(repo) = git2::Repository::open_from_env() {
+                match git_repo_base_ref(&repo, &cached_remote) {
+                    Ok(base_ref_name) => {
+                        debug!("Found base branch reference: {}", base_ref_name);
+                        Some(Cow::Owned(base_ref_name))
+                    }
+                    Err(e) => {
+                        debug!("No base branch reference found: {}", e);
+                        None
+                    }
+                }
+            } else {
+                None
+            }
+        });
     let pr_number = matches.get_one::<u32>("pr_number");
 
     let build_configuration = matches.get_one("build_configuration").map(String::as_str);
@@ -237,7 +259,7 @@ pub fn execute(matches: &ArgMatches) -> Result<()> {
             head_repo_name: head_repo_name.as_deref(),
             base_repo_name,
             head_ref: head_ref.as_deref(),
-            base_ref,
+            base_ref: base_ref.as_deref(),
             pr_number,
         };
         match upload_file(

src/utils/vcs.rs

@@ -249,6 +249,54 @@ pub fn git_repo_head_ref(repo: &git2::Repository) -> Result<String> {
     }
 }
 
+pub fn git_repo_base_ref(repo: &git2::Repository, remote_name: &str) -> Result<String> {
+    // Get the current HEAD commit
+    let head_commit = repo.head()?.peel_to_commit()?;
+
+    // Try to find the remote tracking branch
+    let remote_branch_name = format!("refs/remotes/{remote_name}/HEAD");
+    let remote_ref = match repo.find_reference(&remote_branch_name) {
+        Ok(r) => r,
+        Err(_) => {
+            // If remote/HEAD doesn't exist, try to find the default branch
+            // First try common default branch names
+            for branch in &["main", "master", "develop"] {
+                let remote_branch = format!("refs/remotes/{remote_name}/{branch}");
+                if let Ok(r) = repo.find_reference(&remote_branch) {
+                    return find_merge_base_ref(repo, &head_commit, &r);
+                }
+            }
+            bail!("Could not find remote tracking branch for {}", remote_name);
+        }
+    };
+
+    find_merge_base_ref(repo, &head_commit, &remote_ref)
+}
+
+fn find_merge_base_ref(
+    repo: &git2::Repository,
+    head_commit: &git2::Commit,
+    remote_ref: &git2::Reference,
+) -> Result<String> {
+    let remote_commit = remote_ref.peel_to_commit()?;
+    let merge_base_oid = repo.merge_base(head_commit.id(), remote_commit.id())?;
+
+    // Try to find a branch name that points to this commit
+    let branches = repo.branches(Some(git2::BranchType::Local))?;
+    for (branch, _) in branches.flatten() {
+        if let Ok(branch_commit) = branch.get().peel_to_commit() {
+            if branch_commit.id() == merge_base_oid {
+                if let Some(branch_name) = branch.name()? {
+                    return Ok(branch_name.to_owned());
+                }
+            }
+        }
+    }
+
+    // If no branch name found, return the commit SHA
+    Ok(merge_base_oid.to_string())
+}
+
 fn find_reference_url(repo: &str, repos: &[Repo]) -> Result<Option<String>> {
     let mut non_git = false;
     for configured_repo in repos {

tests/integration/_cases/build/build-upload-help-macos.trycmd

@@ -42,8 +42,8 @@ Options:
           The reference (branch) to use for the upload. If not provided, the current reference will
           be used.
       --base-ref <base_ref>
-          The reference (branch) to use for the upload. If not provided, the current reference will
-          be used.
+          The base reference (branch) to use for the upload. If not provided, the merge-base with
+          the remote tracking branch will be used.
       --pr-number <pr_number>
           The pull request number to use for the upload. If not provided, the current pull request
           number will be used.

tests/integration/_cases/build/build-upload-help-not-macos.trycmd

@@ -41,8 +41,8 @@ Options:
           The reference (branch) to use for the upload. If not provided, the current reference will
           be used.
       --base-ref <base_ref>
-          The reference (branch) to use for the upload. If not provided, the current reference will
-          be used.
+          The base reference (branch) to use for the upload. If not provided, the merge-base with
+          the remote tracking branch will be used.
       --pr-number <pr_number>
           The pull request number to use for the upload. If not provided, the current pull request
           number will be used.