feat: include git commit SHA in PET info response for telemetry regression tracking

crates/pet/build.rs

@@ -4,15 +4,42 @@
 fn main() {
     println!("cargo:rerun-if-env-changed=PET_BUILD_ID");
     println!("cargo:rerun-if-env-changed=BUILD_BUILDID");
+    println!("cargo:rerun-if-env-changed=PET_COMMIT_SHA");
+    println!("cargo:rerun-if-env-changed=BUILD_SOURCEVERSION");
+    println!("cargo:rerun-if-env-changed=GITHUB_SHA");
 
+    // Filter empties per-candidate so an explicitly-set-but-empty primary var
+    // doesn't short-circuit the fallback chain (e.g., `PET_BUILD_ID=""`).
     if let Some(build_id) = std::env::var("PET_BUILD_ID")
         .ok()
-        .or_else(|| std::env::var("BUILD_BUILDID").ok())
         .filter(|value| !value.is_empty())
+        .or_else(|| {
+            std::env::var("BUILD_BUILDID")
+                .ok()
+                .filter(|value| !value.is_empty())
+        })
     {
         println!("cargo:rustc-env=PET_BUILD_ID={build_id}");
     }
 
+    // BUILD_SOURCEVERSION is set by Azure Pipelines; GITHUB_SHA by GitHub Actions.
+    if let Some(commit_sha) = std::env::var("PET_COMMIT_SHA")
+        .ok()
+        .filter(|value| !value.is_empty())
+        .or_else(|| {
+            std::env::var("BUILD_SOURCEVERSION")
+                .ok()
+                .filter(|value| !value.is_empty())
+        })
+        .or_else(|| {
+            std::env::var("GITHUB_SHA")
+                .ok()
+                .filter(|value| !value.is_empty())
+        })
+    {
+        println!("cargo:rustc-env=PET_COMMIT_SHA={commit_sha}");
+    }
+
     #[cfg(target_os = "windows")]
     {
         if std::env::var("CARGO_BIN_NAME").is_err() {

crates/pet/src/jsonrpc.rs

@@ -523,6 +523,8 @@ pub struct InfoResponse {
     pub pet_version: String,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub build_id: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub commit_sha: Option<String>,
 }
 
 impl InfoResponse {
@@ -532,6 +534,9 @@ impl InfoResponse {
             build_id: option_env!("PET_BUILD_ID")
                 .filter(|value| !value.is_empty())
                 .map(ToString::to_string),
+            commit_sha: option_env!("PET_COMMIT_SHA")
+                .filter(|value| !value.is_empty())
+                .map(ToString::to_string),
         }
     }
 }
@@ -1537,14 +1542,45 @@ mod tests {
     }
 
     #[test]
-    fn test_info_response_uses_package_version_and_optional_build_id() {
+    fn test_info_response_uses_package_version_and_optional_build_metadata() {
         let info = InfoResponse::current();
 
         assert_eq!(info.pet_version, env!("CARGO_PKG_VERSION"));
+        // build_id / commit_sha are populated from env vars set at compile time by CI.
+        // For local dev builds they will be None; assert non-empty only when present.
         assert!(info
             .build_id
             .as_deref()
             .is_none_or(|build_id| !build_id.is_empty()));
+        assert!(info
+            .commit_sha
+            .as_deref()
+            .is_none_or(|commit_sha| !commit_sha.is_empty()));
+    }
+
+    #[test]
+    fn test_info_response_serializes_camel_case_and_omits_none() {
+        // Guards the JSON wire format (camelCase rename + skip_serializing_if)
+        // independently of whether CI env vars were set at compile time.
+        let json = serde_json::to_value(InfoResponse {
+            pet_version: "1.2.3".to_string(),
+            build_id: Some("42".to_string()),
+            commit_sha: Some("abc123".to_string()),
+        })
+        .unwrap();
+        assert_eq!(json["petVersion"], "1.2.3");
+        assert_eq!(json["buildId"], "42");
+        assert_eq!(json["commitSha"], "abc123");
+
+        let json = serde_json::to_value(InfoResponse {
+            pet_version: "1.2.3".to_string(),
+            build_id: None,
+            commit_sha: None,
+        })
+        .unwrap();
+        assert_eq!(json["petVersion"], "1.2.3");
+        assert!(json.get("buildId").is_none());
+        assert!(json.get("commitSha").is_none());
     }
 
     #[test]

crates/pet/tests/jsonrpc_client.rs

@@ -26,6 +26,7 @@ pub struct RefreshResult {
 pub struct PetInfoResponse {
     pub pet_version: String,
     pub build_id: Option<String>,
+    pub commit_sha: Option<String>,
 }
 
 #[derive(Debug, Clone, Deserialize, PartialEq, Eq)]

crates/pet/tests/jsonrpc_server_test.rs

@@ -111,16 +111,22 @@ fn assert_single_environment(
 }
 
 #[test]
-fn info_reports_pet_version_and_optional_build_id() {
+fn info_reports_pet_version_and_optional_build_metadata() {
     let client = PetJsonRpcClient::spawn().expect("failed to spawn PET server");
 
     let info = client.info().expect("info request failed");
 
     assert_eq!(info.pet_version, env!("CARGO_PKG_VERSION"));
+    // build_id / commit_sha are populated from env vars set at compile time by CI.
+    // For local dev builds they will be None; assert non-empty only when present.
     assert!(info
         .build_id
         .as_deref()
         .is_none_or(|build_id| !build_id.is_empty()));
+    assert!(info
+        .commit_sha
+        .as_deref()
+        .is_none_or(|commit_sha| !commit_sha.is_empty()));
 }
 
 #[test]

docs/JSONRPC.md

@@ -35,8 +35,15 @@ interface InfoResponse {
   petVersion: string;
   /**
    * Build identifier baked into the binary when built by CI.
+   * Sourced from `PET_BUILD_ID` or Azure Pipelines `BUILD_BUILDID`.
    */
   buildId?: string;
+  /**
+   * Source git commit SHA baked into the binary when built by CI.
+   * Sourced from `PET_COMMIT_SHA`, Azure Pipelines `BUILD_SOURCEVERSION`,
+   * or GitHub Actions `GITHUB_SHA`. Absent for local dev builds.
+   */
+  commitSha?: string;
 }
 ```