Rework the megademo to fit the 80-column source line limit

AKBASIC_MAX_LINE_LENGTH's cut from 256 to 80 left seventeen lines of
examples/megademo unloadable: the sixteen IM$() picture strings (up to
252 characters) and TUNEA/TUNEB's four-bar PLAY strings (174 and 175).
The real ceiling is 78 characters, not 80 -- stdio_readline() refuses a
read that fills the 80-byte buffer without a newline, so content plus
its terminator must fit in 79.

The picture: vaporwave.py's PAYLOAD drops from 240 to 64, so every
emitted IM$(NN) = "..." line fits under the ceiling. chop() no longer
slices blind; it walks the stream a record at a time -- two characters
for a run, three for an R row record -- and never cuts inside one,
because the decoder reads a record's tail with MID on the string it is
walking and a record straddling two IM$ entries decodes as garbage.
The old blind slice at 240 only happened to be safe. verify() now
simulates the CHOPPED strings with the cursor threaded across the
boundaries exactly the way DRAWSTREAM executes them, so a bad cut is
an assertion failure instead of a corrupted screen, and emit_block()
asserts every emitted line fits. The picture is 56 strings where it
was 16; the decoder needed no changes at all, since it already carries
X#/Y# from one IM$ entry to the next.

The music: TUNEA and TUNEB each become four PLAY statements, one bar
apiece. play.c keeps voice, envelope, level and duration state on the
runtime across statements and every PLAY appends to the same queue, so
four bars queue exactly as one long string did. Each bar restates the
V1T3U9S prefix so a bar dropped by QFULL cannot leave the next batch
playing on the drum kit's envelope.

Everything still clears the shrunken pools with room to spare: 1625
source lines of 2048, ~704 array slots of 2048, identifiers within the
24-character symtab key. Verified end to end against this branch's
build: the demo loads, the offscreen host renders every scene, and the
scene-5 still is pixel-identical to vaporwave.py's own preview. The
test suite fails the same seventeen cases with and without this
commit.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ACffnV6F7sxQuG3Y8a1L3s

.gitea/workflows/ci.yaml

@@ -17,7 +17,7 @@ jobs:
           # Not recursive, deliberately. The top-level build needs
           # deps/libakerror and deps/libakstdlib, via add_subdirectory, and
           # nothing else: the golden corpus and the Commodore font now live in
-          # this repository (tests/language/ and assets/fonts/), so
+          # this repository (tests/reference/ and assets/fonts/), so
           # deps/basicinterpret is no longer a build dependency at all.
           # It does *not* need deps/libakgl, which is guarded behind
           # AKBASIC_WITH_AKGL and defaults OFF -- and recursing into it would
@@ -62,9 +62,11 @@ jobs:
         run: |
           cmake -S . -B build
           cmake --build build --parallel 2
-      # The suite is 112 cases: 65 language files with sibling expectations,
+      # The suite is 78 cases: 41 golden files byte-compared against the Go
-      # 43 unit tests, 3 embedding examples, and docs_examples.
+      # reference's own corpus (checked in at tests/reference/, see its README),
-      # Some unit tests assert the *correct* contract for known defects (TODO.md
+      # 9 local golden cases for verbs the reference never implemented, 25 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.
       #

CLAUDE.md

@@ -57,9 +57,9 @@ repeating where you will see them:
   `include/akgl/SDL_GameControllerDB.h`. Change the template or the generator script.
 - **Do not reformat code you are not otherwise changing.** Several files mix tabs and spaces
   and there is no repo-wide formatter; style conversions get their own commit.
-- **Keep `tests/language/` editable.** Its `.bas` programs and sibling `.txt` expectations
+- **Do not edit `tests/reference/`.** Those expectations came from the Go implementation and
-  are changed together when behavior changes. Record deliberate language decisions in
+  are never edited to suit this interpreter. A deliberate divergence goes in
-  `TODO.md` or `docs/13-differences.md`.
+  `tests/reference/README.md`'s divergence table and `docs/13-differences.md`.
 - **Open an issue for outstanding work; do not add it to `TODO.md`.**
   <https://source.starfort.tech/andrew/akbasic/issues>, or `tea issues create --repo
   andrew/akbasic`. Name the file and line, the functional consequence, and what closing it would

CMakeLists.txt

@@ -448,7 +448,7 @@ if(AKBASIC_WITH_AKGL)
   # against.
   #
   # **A byte comparison of a rendered PNG is a deliberate bet**, the same bet
-  # the language corpus makes about golden output: that the dummy video
+  # tests/reference/ already makes about golden output: that the dummy video
   # driver and the software renderer are reproducible. They are, run to run and
   # build to build. What is untested is an SDL upgrade that shifts one pixel of
   # a diagonal, and the answer to that is to regenerate the figures in the same
@@ -531,20 +531,63 @@ if(AKBASIC_WILL_FAIL_TESTS OR AKBASIC_KNOWN_FAILING_TESTS)
   )
 endif()
 
-# The editable language corpus. One CTest case per .bas so a failure names the
+# The reference's own corpus, byte-compared against the sibling .txt. One CTest
-# file. Each program is paired with a sibling .txt expectation; see
+# case per .bas so a failure names the file.
-# tests/language/README.md for the editing rule.
 #
-# The corpus includes programs carried over from the deprecated Go implementation
+# It used to be driven in place out of deps/basicinterpret, on the reasoning that
-# and cases written for this interpreter. Their provenance is useful when
+# copying a submodule's corpus guarantees drift. That reasoning was sound and it
-# investigating a regression, but it does not make any case immutable.
+# has been overruled deliberately: the Go dependency is being deprecated, and a
+# build that cannot run its acceptance suite without cloning the implementation
+# it replaced is not finished. The copy is byte-identical to
+# basicinterpreter@d76162c and tests/reference/README.md records
+# where it came from and what the drift now costs.
+file(GLOB_RECURSE AKBASIC_GOLDEN_CASES
+  RELATIVE "${CMAKE_CURRENT_SOURCE_DIR}/tests/reference"
+  "${CMAKE_CURRENT_SOURCE_DIR}/tests/reference/*.bas"
+)
+
+foreach(_case IN LISTS AKBASIC_GOLDEN_CASES)
+  string(REGEX REPLACE "^tests/" "" _name "${_case}")
+  string(REGEX REPLACE "\\.bas$" "" _name "${_name}")
+  string(REPLACE "/" "_" _name "${_name}")
+  _add_test(
+    NAME golden_${_name}
+    COMMAND ${CMAKE_COMMAND}
+            -DBASIC=$<TARGET_FILE:basic>
+            -DCASE=${CMAKE_CURRENT_SOURCE_DIR}/tests/reference/${_case}
+            -P ${CMAKE_CURRENT_SOURCE_DIR}/tests/golden.cmake
+  )
+endforeach()
+
+if(AKBASIC_GOLDEN_CASES)
+  set(AKBASIC_GOLDEN_NAMES)
+  foreach(_case IN LISTS AKBASIC_GOLDEN_CASES)
+    string(REGEX REPLACE "^tests/" "" _name "${_case}")
+    string(REGEX REPLACE "\\.bas$" "" _name "${_name}")
+    string(REPLACE "/" "_" _name "${_name}")
+    list(APPEND AKBASIC_GOLDEN_NAMES golden_${_name})
+  endforeach()
+  _set_tests_properties(${AKBASIC_GOLDEN_NAMES} PROPERTIES TIMEOUT 30)
+  # An AKGL build of `basic` opens a window, and forty-one of them is not what
+  # anybody running the suite wanted. The dummy driver produces the same stdout,
+  # which is the only thing a golden case compares.
+  if(AKBASIC_WITH_AKGL)
+    _set_tests_properties(${AKBASIC_GOLDEN_NAMES} PROPERTIES
+      ENVIRONMENT "SDL_VIDEODRIVER=dummy;SDL_AUDIODRIVER=dummy;SDL_RENDER_DRIVER=software")
+  endif()
+endif()
+
+# The local golden corpus, for verbs the reference never implemented.
 #
-# Programs carried over from the deprecated Go implementation and cases written
+# Still separate now that the reference's corpus lives in this repository too,
-# for this interpreter use the same editable `.bas`/`.txt` contract. Registered
+# and the reason changed rather than went away: tests/reference/ is a *record* of
-# under local_ so every failure identifies the program that produced it.
+# what the Go implementation did and nothing in it should ever be edited to suit
+# this one, while tests/language/ is ours to change. Registered under local_ so a
+# failure says at a glance which of the two it came from -- and so a diff that
+# touches tests/reference/ stands out as the thing it is.
 #
 # Note what this can and cannot cover. The graphics and sound verbs draw and play
-# rather than print, so what a golden file sees of them is their refusals and
+# rather than print, so what a golden file sees of them is their *refusals* and
 # whatever a program can PRINT about the state they changed. The behaviour that
 # reaches a device is asserted against tests/mockdevice.h instead.
 file(GLOB_RECURSE AKBASIC_LOCAL_CASES

MAINTENANCE.md

@@ -88,7 +88,7 @@ source stays readable as documentation of what the original did. Neither is bind
 
 **It is not a build or test dependency.** Both configurations have been configured, built and
 run from scratch with it moved out of the tree. Its acceptance corpus is checked in at
-`tests/language/` and its Commodore font at `assets/fonts/`.
+`tests/reference/` and its Commodore font at `assets/fonts/`.
 
 ```sh norun
 cd deps/basicinterpret
@@ -351,10 +351,15 @@ name. That is not cosmetic: `add_executable` creates a dependency's targets even
 
 ### The golden corpora
 
-`tests/language/` is the editable language corpus. It includes cases carried over from the
+`tests/reference/` is the Go implementation's own acceptance suite, byte-compared.
-deprecated Go implementation as well as cases written for this interpreter. Every `.bas` file
+**Nothing in it is ever edited to suit this interpreter.** If a case fails, either this
-has a sibling `.txt` expectation, and a new language feature needs that pair as well as unit
+interpreter is wrong or the divergence is deliberate — and a deliberate one goes in
-tests. Change both deliberately in the same commit; provenance does not make a case immutable.
+`tests/reference/README.md`'s divergence table and `docs/13-differences.md`, not into the
+expectation file. `tests/reference/README.md`
+says the same thing at more length.
+
+`tests/language/` is ours and may be changed freely. A new language feature needs a
+`.bas`/`.txt` pair there as well as unit tests.
 
 ### Mutation-check a fix before you believe it
 

README.md

@@ -10,7 +10,7 @@ implementation that started from the Java Lox instructions in
 [craftinginterpreters.com](https://craftinginterpreters.com) and then struck off on its own. That
 project is deprecated. It is vendored here as the behavioural spec to read when a question about
 semantics comes up, and its acceptance corpus is checked in at
-[`tests/language/`](tests/language/README.md) and runs on every build — so nothing about
+[`tests/reference/`](tests/reference/README.md) and runs on every build — so nothing about
 building or testing this project needs it.
 
 ## Quickstart
@@ -24,7 +24,7 @@ ctest --test-dir build --output-on-failure
 
 ```sh norun
 ./build/basic                                          # the REPL
-./build/basic tests/language/functions.bas             # run a program
+./build/basic tests/reference/language/functions.bas   # run a program
 ```
 
 ```basic
@@ -129,7 +129,7 @@ version are catalogued in [`TODO.md`](TODO.md) and summarised for a BASIC progra
 | [`docs/`](docs/README.md) | The guide: eighteen chapters, the language then each hardware area then a reference section for every verb and function, [Chapter 14](docs/14-architecture.md) on the interpreter's own architecture, [Chapter 15](docs/15-error-codes.md) listing every error code, and [Chapters 17](docs/17-tutorial-breakout.md) and [18](docs/18-tutorial-breakout-artwork.md) building a whole game twice |
 | [`MAINTENANCE.md`](MAINTENANCE.md) | For contributors and maintainers: the documentation-example harness, the three test lists, mutation testing, error-code allocation, style |
 | [`TODO.md`](TODO.md) | Outstanding defects, with file, line and consequence |
-| [`tests/language/README.md`](tests/language/README.md) | The editable language corpus and the rule for changing it |
+| [`tests/reference/README.md`](tests/reference/README.md) | Where the golden corpus came from, and the rule for changing it |
 
 API documentation builds with `doxygen Doxyfile`, into `build/docs/html`.
 

TODO.md

@@ -38,7 +38,7 @@ What it changes:
 - **§1.8's message-text contract is now a convention.** Improving a message is allowed; it costs
   a golden file, which is a cost rather than a veto.
 - **§5's bar drops** from "defensible against the golden suite" to defensible on its own merits.
-- **`tests/language/` is the editable language corpus rather than a protected specification.** Diverging from
+- **`tests/reference/` becomes a regression suite rather than a specification.** Diverging from
   it is allowed and must be deliberate and recorded — see its README.
 
 What it does **not** change:
@@ -306,13 +306,13 @@ to `Println`, which adds another.
 **This used to be a hard contract and is now a default.** The Go implementation is deprecated
 and will not be updated, so the two projects are no longer required to match — see §0.1. What
 survives is the practical half: these strings and this newline behaviour are what every
-expectation in `tests/language/` was written against, so changing one means changing the paired
+expectation in `tests/reference/` was written against, so changing one means changing golden
 files, and that is worth doing on purpose rather than by accident. A message that reads
 awkwardly *may* now be improved; do it deliberately, move the expectations in the same commit,
 and add a line to §5.
 
 Numeric formatting still matches the reference: integers via `%" PRId64 "`, floats via `%f`
-(Go's `%f` and C's `%f` both give six decimals — `tests/language/arithmetic/float.txt`
+(Go's `%f` and C's `%f` both give six decimals — `tests/reference/language/arithmetic/float.txt`
 confirms). No reason to change it, which is different from not being allowed to.
 
 ### 1.9 Which `libakstdlib` calls are cleared for use — **the bans are lifted**
@@ -375,7 +375,7 @@ Phases 0 through 6 of the original plan are done. The interpreter builds clean u
 
 It *did* reproduce the reference byte for byte, and that claim is retired rather than broken:
 §0.1 released it, and one case has since diverged deliberately (§6 item 16, listed in
-`tests/language/README.md`). Everything else still matches, which is worth knowing but is no
+`tests/reference/README.md`). Everything else still matches, which is worth knowing but is no
 longer a gate.
 
 ```sh
@@ -408,16 +408,17 @@ and the only path that existed — `AKBASIC_MODE_RUNSTREAM` reading through the
 is the code the README quotes, built by every build and registered as a CTest case so a
 signature change breaks the build rather than rotting the document.
 
-**The acceptance suite is the editable language corpus, checked in at `tests/language/`.** All
+**The acceptance suite is the reference's own corpus, checked in at `tests/reference/`.** All
-65 `.bas` files are registered as individual CTest cases and compared against their `.txt`
+41 `.bas` files are registered as individual CTest cases and byte-compared against their `.txt`
 — including the trailing double newline on an error line (§1.8).
 
 It was driven *in place* out of `deps/basicinterpret` until 2026-07-31, on the reasoning that
 copying a submodule's corpus guarantees drift. That reasoning was sound and was overruled
 deliberately: the Go dependency is being deprecated, and a build that cannot run its own
 acceptance suite without cloning the implementation it replaced is not finished. The copy is
-originally byte-identical to `basicinterpreter@d76162c`, and `tests/language/README.md` records the
+byte-identical to `basicinterpreter@d76162c`, and `tests/reference/README.md` records the
-provenance and the rule that programs and expectations are edited together deliberately.
+provenance, the cost of the drift nobody is watching for now, and the rule that those
+expectations are never edited to suit this interpreter.
 
 **Nothing in the build or the suite needs `deps/basicinterpret` any more**, and that is checked
 rather than assumed — both configurations were configured, built and run from scratch with the
@@ -1025,7 +1026,7 @@ deviations from the reference's *program*: `main.go` and the SDL half of
 
     **What it costs a program:** a listing that used `INPUT$`, `LEN#` or `GOTO%` as a variable
     stops parsing, and the fix is to rename the variable. One case in the reference's own corpus
-    did exactly that; see `tests/language/examples/strreverse.bas`.
+    did exactly that; see `tests/reference/README.md`.
 
 ### Deviations in statement separation
 
@@ -1390,10 +1391,10 @@ deviations from the reference's *program*: `main.go` and the SDL half of
     **This one moved a golden file.** A line with no number used to be filed under the loader's
     cursor unchanged — that is, on top of the line before it — so two unnumbered lines in a row
     silently lost the first, and a *blank* line erased whatever preceded it. The reference does
-    the same, and `tests/language/arithmetic/integer.bas` is the proof: four `PRINT`
+    the same, and `tests/reference/language/arithmetic/integer.bas` is the proof: four `PRINT`
     statements, an expectation with three values, and a trailing blank line that erased
     `40 PRINT 4 - 2` before the program ran. The expectation is now `4 4 2 2` and
-    `tests/language/README.md` records it.
+    `tests/reference/README.md` records it.
 
     In its place: `akbasic_runtime_file_line()` (`src/runtime.c`) is the one implementation of
     the rule, shared by `akbasic_runtime_load()`, RUNSTREAM and `DLOAD`. A numbered line is
@@ -1585,9 +1586,9 @@ be reproduced before it can be fixed.