ci: expose compiler cache wall time and backend

.github/workflows/ci-macos.yml

@@ -927,7 +927,10 @@ jobs:
         env:
           HOSTED_COMPILE_SECONDS: ${{ steps.hosted-compile.outputs.seconds }}
           HOSTED_COMPILE_OUTCOME: ${{ steps.hosted-compile.outcome }}
-          SEED_DISTANCE: ${{ steps.seed-derived-data.outputs.seed_distance || steps.prefer-seed.outputs.seed_distance }}
+          # Report only the seed that adopt actually installed. prefer-seed's
+          # distance describes a candidate and can remain set when adoption
+          # fails or is skipped.
+          SEED_DISTANCE: ${{ steps.seed-derived-data.outputs.seed_distance }}
           SEED_SECONDS: ${{ steps.seed-derived-data.outputs.seconds }}
         run: |
           set -euo pipefail

scripts/ci/build_metrics.py

@@ -33,6 +33,14 @@
     r"^\s*(.+?)(?:\s+\(\d+\s+tasks?\)\s+\|)?\s+"
     r"([0-9]+(?:\.[0-9]+)?) seconds\s*$"
 )
+CACHE_PLUGIN_SETTING_RE = re.compile(
+    r"\bCOMPILATION_CACHE_ENABLE_PLUGIN\s*=\s*YES\b",
+    re.IGNORECASE,
+)
+CACHE_REMOTE_SETTING_RE = re.compile(
+    r"\bCOMPILATION_CACHE_REMOTE_SERVICE_PATH\s*=\s*\S+",
+    re.IGNORECASE,
+)
 CACHE_VALUES = {"Cache hit": "hit", "Cache miss": "miss"}
 
 
@@ -140,6 +148,15 @@ def parse_log(path: Path) -> dict[str, object]:
         "swift_compile_events": sum(swift_compile_by_target.values()),
         "swift_emit_module_events": sum(swift_emit_by_target.values()),
         "cacheable_tasks": cache["hit"] + cache["miss"],
+        # The command's build-settings echo is the only portable evidence of
+        # whether Xcode was given the fleet plugin/socket. Keep the value
+        # categorical; never copy the socket path into telemetry.
+        "cache_backend": (
+            "fleet"
+            if CACHE_PLUGIN_SETTING_RE.search("\n".join(lines))
+            and CACHE_REMOTE_SETTING_RE.search("\n".join(lines))
+            else "local"
+        ),
         "timing_summary_seconds": timing_summary(lines),
         "targets": targets,
     }
@@ -162,6 +179,7 @@ def aggregate(schemes: list[dict[str, object]]) -> dict[str, object]:
 
     return {
         **dict(totals),
+        "cache_backend": "fleet" if any(scheme.get("cache_backend") == "fleet" for scheme in schemes) else "local",
         "timing_summary_seconds": dict(sorted(timing.items())),
         "targets": {
             target: dict(values)
@@ -233,8 +251,10 @@ def build_receipt(
         "hit_rate": round(hits / cacheable, 6) if cacheable else None,
         "seed_distance": seed_distance,
         "compile_seconds": compile_phase,
+        "compile_wall_seconds": compile_seconds,
         "fetch_seconds": fetch_seconds,
         "link_seconds": link_phase,
+        "cache_backend": aggregate_values.get("cache_backend", "local"),
     }
     return {
         "schema_version": 1,

tests/test_build_metrics.py

@@ -4,6 +4,9 @@
 import importlib.util
 import json
 from pathlib import Path
+import os
+import subprocess
+import sys
 import tempfile
 import unittest
 
@@ -56,6 +59,14 @@
 ** BUILD SUCCEEDED **
 """
 
+FLEET_CACHE_LOG = """COMPILATION_CACHE_ENABLE_PLUGIN = YES
+COMPILATION_CACHE_REMOTE_SERVICE_PATH = /Users/Shared/cmux-build-fleet/xcode/fleet-cas.sock
+Build Timing Summary
+CompileSwiftSources (2 tasks) | 3.000 seconds
+Ld (1 task) | 0.500 seconds
+** BUILD SUCCEEDED **
+"""
+
 
 class BuildMetricsTests(unittest.TestCase):
     def test_parse_log_attributes_cache_and_swift_work(self):
@@ -156,6 +167,11 @@ def test_ci_wires_advisory_receipt_and_timing_summary(self):
         self.assertIn("steps.hosted-compile.outcome != 'skipped'", workflow)
         self.assertIn("--compile-outcome \"$HOSTED_COMPILE_OUTCOME\"", workflow)
         self.assertIn("--host-telemetry \"$RUNNER_TEMP/glaeda-compile-telemetry.json\"", workflow)
+        self.assertIn("SEED_DISTANCE: ${{ steps.seed-derived-data.outputs.seed_distance }}", workflow)
+        self.assertNotIn(
+            "SEED_DISTANCE: ${{ steps.seed-derived-data.outputs.seed_distance || steps.prefer-seed.outputs.seed_distance }}",
+            workflow,
+        )
         self.assertIn("steps.build-metrics.outcome == 'success'", workflow)
         self.assertIn("continue-on-error: true", workflow)
 
@@ -179,10 +195,56 @@ def test_receipt_discovers_logs_and_activity_metadata(self):
         self.assertEqual(receipt["compiler_cache"]["cacheable_tasks"], 3)
         self.assertEqual(receipt["compiler_cache"]["compile_seconds"], 12.5)
         self.assertEqual(receipt["compiler_cache"]["link_seconds"], 2.25)
+        self.assertEqual(receipt["compiler_cache"]["compile_wall_seconds"], 42.5)
+        self.assertEqual(receipt["compiler_cache"]["cache_backend"], "local")
         self.assertEqual(receipt["derived_data_log_count"], 1)
         self.assertEqual(receipt["activity_logs"], [{"name": "one.xcactivitylog", "bytes": 3}])
         json.dumps(receipt)
 
+    def test_receipt_identifies_fleet_cache_backend_without_emitting_paths(self):
+        with tempfile.TemporaryDirectory() as directory:
+            derived = Path(directory)
+            (derived / "cmux-build.log").write_text(FLEET_CACHE_LOG)
+
+            receipt = build_metrics.build_receipt(derived, 9.25, compile_outcome="success")
+
+        self.assertEqual(receipt["compiler_cache"]["cache_backend"], "fleet")
+        self.assertEqual(receipt["compiler_cache"]["compile_wall_seconds"], 9.25)
+        self.assertNotIn("fleet-cas.sock", json.dumps(receipt["compiler_cache"]))
+
+    def test_host_sidecar_carries_wall_time_and_backend(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            derived = root / "derived"
+            derived.mkdir()
+            (derived / "cmux-build.log").write_text(FLEET_CACHE_LOG)
+            output = root / "receipt.json"
+            host = root / "host.json"
+            env = {**os.environ, "GITHUB_RUN_ID": "123", "GITHUB_RUN_ATTEMPT": "2"}
+            subprocess.run(
+                [
+                    sys.executable,
+                    str(SCRIPT),
+                    str(derived),
+                    "--output",
+                    str(output),
+                    "--compile-seconds",
+                    "9.25",
+                    "--compile-outcome",
+                    "success",
+                    "--host-telemetry",
+                    str(host),
+                ],
+                check=True,
+                env=env,
+            )
+            sidecar = json.loads(host.read_text())
+
+        self.assertEqual(sidecar["compile_wall_seconds"], 9.25)
+        self.assertEqual(sidecar["cache_backend"], "fleet")
+        self.assertEqual(sidecar["run_id"], "123")
+        self.assertEqual(sidecar["run_attempt"], "2")
+
 
 if __name__ == "__main__":
     unittest.main()