Fix hotpatching when the bin target's crate name differs from the package name (#5719) (#5720)

(cherry picked from commit 4c51c12bc19d78983cb2992f319ebe996acb2893)

Signed-off-by: Nico Burns <nico@nicoburns.com>

packages/cli/src/build/builder.rs

@@ -408,7 +408,9 @@ impl AppBuilder {
         // patch (starting from changed_crates + cascade). That serves a different purpose — it only
         // compiles what changed now, not everything ever modified. Both use workspace_dependents_of
         // for the BFS, so they stay in sync automatically.
-        let tip_crate_name = self.build.main_target.replace('-', "_");
+        // Track the tip by *package* name — that's the identity used by the file→crate
+        // mapping and the workspace dependents graph (the bin target name can differ).
+        let tip_crate_name = self.build.tip_package_name();
         self.modified_crates.insert(tip_crate_name.clone());
 
         // Add changed crates and their transitive workspace dependents (cascade).

packages/cli/src/build/link.rs

@@ -614,7 +614,9 @@ impl BuildRequest {
         modified_crates: &HashSet<String>,
     ) -> Result<Vec<String>> {
         // Exclude the tip crate — it's compiled separately via cargo_build after replay.
-        let tip = self.tip_crate_name();
+        // Modified crates are tracked by *package* name, which can differ from the bin
+        // target name (`tip_crate_name()`), e.g. package `browser` with `[[bin]] name = "blitz"`.
+        let tip = self.tip_package_name();
         let crates: HashSet<&String> = modified_crates
             .iter()
             .filter(|name| **name != tip)

packages/cli/src/build/request.rs

@@ -2581,6 +2581,16 @@ impl BuildRequest {
         self.main_target.replace('-', "_")
     }
 
+    /// The workspace package name of the tip crate (hyphens replaced with underscores).
+    ///
+    /// This can differ from `tip_crate_name()` when the binary target is named differently
+    /// than its package (e.g. package `browser` with `[[bin]] name = "blitz"`). Use this for
+    /// workspace-graph lookups (which are keyed by package name) and `tip_crate_name()` for
+    /// rustc `--crate-name` keys like `{name}.bin`.
+    pub(crate) fn tip_package_name(&self) -> String {
+        self.package().name.replace('-', "_")
+    }
+
     /// Stderr captured from the linker during the last build. Written by the linker
     /// interception in `rustcwrapper` and read back to surface warnings/errors to the user.
     fn link_err_file(&self) -> PathBuf {
@@ -3095,7 +3105,7 @@ impl BuildRequest {
             })
             .collect();
 
-        let tip = self.tip_crate_name();
+        let tip = self.tip_package_name();
         let Some(tip_nid) = krates.workspace_members().find_map(|m| match m {
             krates::Node::Krate { id, krate, .. } if krate.name.replace('-', "_") == tip => {
                 krates.nid_for_kid(id)

packages/cli/src/serve/runner.rs

@@ -1187,7 +1187,7 @@ impl AppServer {
     /// Uses BFS from the tip crate through its workspace dependencies to find the path.
     /// If the changed crate IS the tip crate, returns just `[tip]`.
     pub(crate) fn workspace_dep_chain(&self, changed_crate: &str) -> Vec<String> {
-        let tip_name = self.client.build.main_target.replace('-', "_");
+        let tip_name = self.client.build.tip_package_name();
 
         // If the changed crate is the tip, no chain needed
         if changed_crate == tip_name {