Emit a per-job sccache statistics table to the GitHub job summary

KISS analogue of upstream llama.cpp's ccache-action "CCache Statistics" table,
but for this repo's sccache-over-Depot cache (ccache-action can't be dropped in:
it manages its own ccache + actions/cache backend, conflicting with the Depot
WebDAV design). build.sh/build.bat already print `sccache --show-stats` to the
log; now, when running in CI (GITHUB_STEP_SUMMARY set) and sccache was actually
the launcher, they also parse those stats and append a small markdown table:

  ### sccache statistics
  | Cache hits | Requests | Hit rate |
  |------------|----------|----------|
  | 589        | 600      | 98.2%    |

Per-job (GitHub does not merge job summaries), covering every native build job
uniformly — build.sh handles the dockcross/native-Linux/aarch64/vulkan-linux and
macOS jobs; build.bat the Windows jobs. Parses the text stats (top-level
"Compile requests" = total, top-level "Cache hits" = hits; the per-language
"Cache hits (C/C++)" line is skipped by the digit-anchored regex). Best-effort:
skipped silently if the numbers can't be parsed or there were no requests, and
never emitted for local runs (no GITHUB_STEP_SUMMARY) — so local builds are
untouched.

Verified the build.sh parse end-to-end against a realistic sccache --show-stats
sample (req=600, hits=589 -> 98.2%, with the "Compile requests executed" line
correctly excluded); build.sh passes bash -n. The Windows batch path (integer
math with rounding, escaped pipes/parens) is validated by CI on the Windows
runners.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HL7d4uQ3cKR5HwYFPvZvv7

Author: claude

.github/build.bat

@@ -60,6 +60,28 @@ REM was wired in as the launcher.
 if defined LAUNCH (
     echo build.bat: sccache --show-stats
     sccache --show-stats
+    REM KISS per-job cache summary in the GitHub Actions job summary (like upstream llama.cpp's
+    REM ccache-action table). Parse the text stats: the top-level "Compile requests" line is the
+    REM total and the top-level "Cache hits" line is the hits (the per-language "Cache hits (C/C++)"
+    REM line has "(" after the label, so the digit-anchored findstr regex skips it). Only in CI
+    REM (GITHUB_STEP_SUMMARY set); local runs are untouched. Best-effort -- skipped if the two
+    REM numbers can't be parsed or there were no requests. Integer math with rounding to one decimal.
+    if defined GITHUB_STEP_SUMMARY (
+        set "SCC_REQ="
+        set "SCC_HITS="
+        for /f "tokens=3" %%a in ('sccache --show-stats 2^>nul ^| findstr /r /c:"^Compile requests  *[0-9]"') do set "SCC_REQ=%%a"
+        for /f "tokens=3" %%a in ('sccache --show-stats 2^>nul ^| findstr /r /c:"^Cache hits  *[0-9]"') do set "SCC_HITS=%%a"
+        if defined SCC_REQ if defined SCC_HITS if !SCC_REQ! gtr 0 (
+            set /a SCC_RATE10=^(!SCC_HITS! * 1000 + !SCC_REQ! / 2^) / !SCC_REQ!
+            set /a SCC_WHOLE=!SCC_RATE10! / 10
+            set /a SCC_DEC=!SCC_RATE10! %% 10
+            >>"%GITHUB_STEP_SUMMARY%" echo ### sccache statistics
+            >>"%GITHUB_STEP_SUMMARY%" echo.
+            >>"%GITHUB_STEP_SUMMARY%" echo ^| Cache hits ^| Requests ^| Hit rate ^|
+            >>"%GITHUB_STEP_SUMMARY%" echo ^|------------^|----------^|----------^|
+            >>"%GITHUB_STEP_SUMMARY%" echo ^| !SCC_HITS! ^| !SCC_REQ! ^| !SCC_WHOLE!.!SCC_DEC!%% ^|
+        )
+    )
 )
 
 REM Propagate a build failure as a non-zero exit (a prior bug let a failed `cmake

.github/build.sh

@@ -160,5 +160,26 @@ rm -f "$build_log"
 # crashing sccache (or the mid-build retry disabled it), re-invoking it here would just repeat
 # the crash output (harmless but noisy).
 if [ -n "$LAUNCH" ] && command -v sccache >/dev/null 2>&1; then
-  sccache --show-stats || true
+  sccache_stats="$(sccache --show-stats 2>/dev/null || true)"
+  printf '%s\n' "$sccache_stats"
+  # KISS per-job cache summary in the GitHub Actions job summary (like upstream llama.cpp's
+  # ccache-action table). Parse the text stats: the top-level "Compile requests" line is the
+  # total and the top-level "Cache hits" line is the hits (the per-language "Cache hits (C/C++)"
+  # line has "(" after the label, so the digit-anchored regex skips it). Only runs in CI
+  # (GITHUB_STEP_SUMMARY set); local runs are untouched. Best-effort — skips silently if the two
+  # numbers can't be parsed or there were no requests.
+  if [ -n "${GITHUB_STEP_SUMMARY:-}" ] && [ -n "$sccache_stats" ]; then
+    sccache_req="$(printf '%s\n' "$sccache_stats" | awk '/^Compile requests[[:space:]]+[0-9]/{print $NF; exit}')"
+    sccache_hits="$(printf '%s\n' "$sccache_stats" | awk '/^Cache hits[[:space:]]+[0-9]/{print $NF; exit}')"
+    if [ -n "$sccache_req" ] && [ -n "$sccache_hits" ] && [ "$sccache_req" -gt 0 ] 2>/dev/null; then
+      sccache_rate="$(awk "BEGIN{printf \"%.1f\", ($sccache_hits/$sccache_req)*100}")"
+      {
+        echo "### sccache statistics"
+        echo ""
+        echo "| Cache hits | Requests | Hit rate |"
+        echo "|------------|----------|----------|"
+        echo "| ${sccache_hits} | ${sccache_req} | ${sccache_rate}% |"
+      } >> "$GITHUB_STEP_SUMMARY"
+    fi
+  fi
 fi

CLAUDE.md

@@ -358,7 +358,13 @@ jobs therefore set `BUILD_JOBS: 2` to bound peak memory.
 **`sccache` → Depot Cache — shared compiler cache.** When `USE_CACHE=true` **and** `sccache`
 plus a cache token are present, `build.sh` adds
 `-DCMAKE_C_COMPILER_LAUNCHER=sccache -DCMAKE_CXX_COMPILER_LAUNCHER=sccache` and prints
-`sccache --show-stats`. The cache lives in **Depot Cache** over sccache's **WebDAV** backend:
+`sccache --show-stats`. **Per-job cache summary:** when running in CI (`GITHUB_STEP_SUMMARY` set),
+`build.sh`/`build.bat` also parse those stats and append a small `### sccache statistics` table
+(`Cache hits | Requests | Hit rate`) to the job summary — the sccache/Depot analogue of upstream
+llama.cpp's `ccache-action` "CCache Statistics" table, per-job (GitHub does not merge job
+summaries). It is best-effort (skipped silently if the numbers can't be parsed) and only emitted
+when sccache was actually the launcher; local runs (no `GITHUB_STEP_SUMMARY`) are untouched. The
+cache lives in **Depot Cache** over sccache's **WebDAV** backend:
 
 - `SCCACHE_WEBDAV_ENDPOINT: https://cache.depot.dev`
 - `SCCACHE_WEBDAV_TOKEN: ${{ secrets.DEPOT_TOKEN }}` — a Depot **organization** token, stored