Cover -DAKBASIC_WITH_AKGL=ON in CI

A fifth push job, akgl_build: the text sink and the graphics, audio and input
backends, plus the akgl_backends suite that drives them against a real software
renderer under the dummy video and audio drivers and reads the pixels back.

It stays a separate job rather than a flag on cmake_build because
AKBASIC_WITH_AKGL is off by default and that default is the claim being made:
the interpreter and its whole 70-case suite build and pass on a machine with no
SDL. Keeping the two jobs apart proves that on every push instead of asserting
it.

Deferring this assumed it needed submodules: recursive and a long build. Both
guesses were wrong, and measurement is the only reason we know:

- Recursive is not needed and costs 461 MB. It descends into SDL_image/external,
  SDL_mixer/external and SDL_ttf/external -- aom, dav1d, libjxl, libtiff,
  mpg123, opus, flac and a dozen more -- and not one of them is used. Every one
  configures as "Could NOT find". Six submodules initialised non-recursively
  take about 25 seconds instead.
- The build is roughly a minute of CPU across 330 object files, because SDL3
  compiles out almost every backend that is not wanted here.

The one real system dependency is libfreetype-dev and libharfbuzz-dev. SDL_ttf
reports "Using system freetype library" and links libfreetype.so.6; without them
it would reach for deps/SDL_ttf/external/freetype, which the checkout
deliberately does not clone. Two apt packages against two more submodules.

Every step was run verbatim from a clean clone before being written down --
checkout, submodule init, configure, build and test -- rather than inferred from
the working tree. 71/71.

Also corrects three counts elsewhere in the file that had gone stale: the suite
is 70 cases rather than 61, line coverage is 93.5% rather than 92.3%, and branch
coverage reads 18% rather than 17%. Those numbers are assertions about the gate,
so a wrong one is worse than none.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -32,12 +32,17 @@ jobs:
         run: |
           cmake -S . -B build
           cmake --build build --parallel
-      # The suite is 61 cases: 41 golden files byte-compared against the Go
-      # reference's own corpus, 17 unit tests, 2 embedding examples, and 1
+      # The suite is 70 cases: 41 golden files byte-compared against the Go
+      # reference's own corpus, 5 local golden cases for verbs the reference
+      # never implemented, 21 unit tests, 2 embedding examples, and 1
       # known-failing test that asserts the *correct* contract for defects
       # carried over from the reference (TODO.md section 6). A green run
       # therefore does not mean defect-free -- see AKBASIC_KNOWN_FAILING_TESTS.
       #
+      # AKBASIC_WITH_AKGL is off here, which is the point rather than an
+      # omission: this job is what proves the interpreter builds and passes on a
+      # machine with no SDL. The akgl_build job below covers the other half.
+      #
       # --output-junit resolves relative to the test dir, so give an absolute
       # path to land the report in the workspace root for the reporter below.
       - name: test (JUnit)
@@ -91,11 +96,15 @@ jobs:
         run: |
           sudo apt-get update -y
           sudo apt-get install -y cmake gcc gcovr
-      # The gate is a ratchet, not a target: src/ sits at 92.3% of lines and
-      # 96.9% of functions, so 90 fails on a real regression (a test deleted, or
+      # The gate is a ratchet, not a target: src/ sits at 93.5% of lines and
+      # 97.8% of functions, so 90 fails on a real regression (a test deleted, or
       # new untested code added) without tripping over rounding.
       #
-      # There is deliberately no branch gate. Branch coverage reads about 17%
+      # The akbasic_akgl target is not in this figure. It is not built in a
+      # default configuration, and instrumenting it would drag SDL into the
+      # coverage job for four thin adaptors.
+      #
+      # There is deliberately no branch gate. Branch coverage reads about 18%
       # and is not a meaningful number here, for the reason libakgl's and
       # libakstdlib's TODO.md both record: the akerror control-flow macros expand
       # into large branch trees at every call site, most of them unreachable in
@@ -130,6 +139,84 @@ jobs:
           if-no-files-found: warn
       - run: echo "🍏 This job's status is ${{ job.status }}."
 
+  akgl_build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v4
+        with:
+          # submodules: true, *not* recursive, and then the libakgl dependencies
+          # by hand in the next step. Recursive would work and costs an extra
+          # 461 MB: it descends into SDL_image/external, SDL_mixer/external and
+          # SDL_ttf/external, which are aom, dav1d, libjxl, libtiff, mpg123,
+          # opus, flac, freetype, harfbuzz and a dozen more. None of them is
+          # used -- every one configures as "Could NOT find" or falls back to
+          # the system copy -- so cloning them is pure checkout time.
+          submodules: true
+      # libakgl builds its vendored SDL only when it is the top-level project;
+      # embedded it takes a find_package path instead, so our CMakeLists declares
+      # those targets first and needs the submodules present. Six of them, none
+      # recursive. Filed upstream as libakgl API-gap item 5.
+      - name: libakgl dependencies
+        run: |
+          git -C deps/libakgl submodule update --init \
+            deps/SDL deps/SDL_image deps/SDL_mixer deps/SDL_ttf \
+            deps/jansson deps/semver
+      # libfreetype-dev and libharfbuzz-dev are load-bearing, not incidental.
+      # SDL_ttf prefers the system copies -- it reports "Using system freetype
+      # library" and links libfreetype.so.6 -- and without them it would reach
+      # for deps/SDL_ttf/external/freetype, which the checkout above
+      # deliberately does not clone. Installing two dev packages is much cheaper
+      # than cloning freetype and harfbuzz.
+      - name: dependencies
+        run: |
+          sudo apt-get update -y
+          sudo apt-get install -y cmake gcc g++ pkg-config \
+            libfreetype-dev libharfbuzz-dev
+      # The akgl-backed half: the text sink and the graphics, audio and input
+      # backends, plus the akgl_backends suite that drives them against a real
+      # software renderer and reads the pixels back.
+      #
+      # It is a separate job rather than a flag on cmake_build because
+      # AKBASIC_WITH_AKGL is off by default and that default is the point: the
+      # interpreter and its whole 70-case suite build and pass on a machine with
+      # no SDL. Keeping the two apart is what proves that claim on every push
+      # rather than asserting it.
+      #
+      # Cost, measured rather than guessed: about 25 s to clone the six
+      # submodules, 25 s to configure and 330 object files to compile -- roughly
+      # a minute of CPU. Cheaper than it looks, because SDL3 compiles out almost
+      # every backend it does not need here.
+      - name: build with libakgl
+        run: |
+          cmake -S . -B build-akgl -DAKBASIC_WITH_AKGL=ON
+          cmake --build build-akgl --parallel
+      # Dummy video and audio drivers: the suite creates a 128x128 software
+      # renderer and reads it back with SDL_RenderReadPixels, so it needs no
+      # display, no sound card and no offscreen harness. Same approach
+      # deps/libakgl/tests/draw.c takes.
+      #
+      # 71 cases: the 70 the default build runs, plus akgl_backends. The other
+      # 70 are run here too on purpose -- they are the ones that must keep
+      # passing when SDL *is* present, and a linker that picked up the wrong
+      # akstdlib or akerror would show up here first.
+      - name: test with libakgl
+        env:
+          SDL_VIDEODRIVER: dummy
+          SDL_AUDIODRIVER: dummy
+        run: ctest --test-dir build-akgl --output-on-failure --output-junit "$(pwd)/ctest-akgl-junit.xml"
+      - name: publish test results
+        if: always()
+        uses: mikepenz/action-junit-report@v4
+        with:
+          report_paths: 'ctest-akgl-junit.xml'
+          annotate_only: true
+          detailed_summary: true
+          include_passed: true
+          fail_on_failure: 'true'
+          check_name: 'akgl test results'
+      - run: echo "🍏 This job's status is ${{ job.status }}."
+
   mutation_test:
     runs-on: ubuntu-latest
     steps: