S16 Phase 3, slice 2: griff swang expand — law 1 by construction

[PhysShell]

What

The second Phase 3 slice: griff swang expand runs a program's pattern pipeline up to map_rhythm and prints the canonical griff.pattern-expansion JSON to stdout (the program's export owns the only musical output; an inspection command does not get a second path to own — spec updated first).

Strict red→green per commit:

• docs(swang): the expand contract — stdout, and expansion-time diagnostic locations by §1.5's layers.
• test(swang): red + green — parse_with_spans: a side table with the four owning-word spans (kernel literal, unit, tail, source). Not AST fields: Program equality and the roundtrip law stay span-free; parse() becomes the span-dropping wrapper. One parser, two entry points.
• refactor(cli): compile_pattern_flaws → PatternFlaw — the pattern compiler now fails as typed data named by the vocabulary site that owns the fix (kernel / unit / score geometry / density / budget-with-NodePath / lowering / silent expansion / silent window). compile_pattern becomes its transport renderer: into_transport() reproduces today's codes, flags, and messages byte-for-byte. §1.5's "core emits pure data, frontends render" now holds where it was being violated. No behavior change — all 19 transport contract tests untouched.
• test(cli): red + green — five laws for expand:
  • Law 1, end to end: the program equivalent of a Phase-2 CLI command produces a byte-identical artifact — proven against --emit-rhythm-expansion output, and guaranteed by construction (both frontends drive the same compile_pattern_flaws).
  • Structural = NodePath: a budget breach renders error[SWG0201] (<file>: node root): … — the whole-grid check breaks at the root; dotted child indices otherwise.
  • Score-borne at the quoted source value, time-domain at the owning value: a unit that does not divide the 7/8 bar is SWG0301 at <file>:7:<col> — the unit value's span, not a flag that no longer exists.
  • Program vocabulary: the silent bars window and the rejected tail advise bars and rest_pad — no --rhythm-*, no rest-pad.

Law status after this slice

§3.5 law	Status
1 (expand byte-parity, canonical subset)	covered here
2, 3, 6, 7	covered in #118
4 (code parity, layered locations)	parse layer in #118; expansion layer here (NodePath / quoted source value / owning value)
5 (build parity split auto/named)	next slice

Fuzz targets (ADR-0010) follow build — the last Phase 3 slice.

Known local-only failure: missing_file_golden on Russian-locale Windows (pre-existing).

After merge

Phase 3 slice 3 red: griff swang build — law 5: under strategy auto byte-parity with griff generate at the same seeds; under a named strategy, the first ranked candidate of that strategy from the unchanged ranked set, written to the program's own export.

🤖 Generated with Claude Code

https://claude.ai/code/session_01NkqJUU6d1sW1RAfvyHrqVM

Summary by CodeRabbit

• New Features

  • Added griff swang expand to compile rhythm patterns and print the canonical expansion JSON to stdout.
  • Enhanced diagnostics with more precise source locations for kernels, units, tails, and sources.
  • Added clearer, targeted error codes/messages for expansion and validation failures (e.g., budget, silent windows, rejected tails).

• Documentation

  • Updated the swang Phase 3 spec to precisely define check | fmt | expand | build behavior and where diagnostics point.

• Bug Fixes

  • Improved diagnostic consistency and ensured swang expand output matches existing generation transport results.

[coderabbitai]

📝 Walkthrough

Walkthrough

Swang gains span-aware parsing, typed rhythm compilation failures, and a new griff swang expand command that emits canonical expansion JSON with stable source-located diagnostics. Integration tests cover output parity, budget failures, and program-specific error vocabulary.

Changes

Swang expansion flow

Layer / File(s)	Summary
Span-aware program parsing swang/src/syntax.rs	Adds ProgramSpans and parse_with_spans, capturing kernel, unit, tail, and source locations while preserving parse.
Typed rhythm compilation failures cli/src/rhythm_pattern.rs	Introduces PatternFlaw and compile_pattern_flaws, deferring conversion to transport diagnostics for rhythm, budget, lowering, and silent-expansion failures.
Swang expand command and rendering cli/src/main.rs	Adds griff swang expand, compiles through map_rhythm, renders stable SWG____ diagnostics, and prints expansion JSON.
Expansion parity and acceptance coverage cli/tests/swang_cmd.rs, docs/swang/spec.md	Tests byte-level output parity and source-located diagnostics, and documents expand output ownership and diagnostic span rules.

Estimated code review effort: 4 (Complex) | ~45 minutes

Possibly related PRs

• PhysShell/griff#116: Shares the rhythm compilation and SWG____ diagnostic paths.
• PhysShell/griff#117: Updates the Phase 3 expand/build contract and diagnostic location rules.

Suggested labels: enhancement

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title is specific and accurately summarizes the main change: the Phase 3 slice for griff swang expand.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/s16-phase3-expand

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[chatgpt-codex-connector]

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[PhysShell]

Blocker closed at head 40fe6c3, one docs+test commit as prescribed:

1. Spec disambiguated in the value's favor: 'score-borne facts sit at the quoted source value's span — the path literal identifies the offending score, and the keyword never changes.'
2. Executable verdict for the uncovered branch: a meter-change MIDI (4/4 → 7/8 at bar 1, encoded independently in the test) drives SWG0304 to exactly <file>:9:16 — the opening quote of the source path literal — asserting the code, the precise line:column, and the absence of INPUT and transport flags. 12/12.
3. Codex thread answered (ambiguity accepted, keyword-span rejected per the arbiter's resolution) and resolved.
4. rhythm_pattern module doc no longer claims errors leave only as PatternDiagnostics — it now names the PatternFlaw core and both renderers.

No other changes: no path-resolution semantics, no fuzzing, no generation integration. Gate: fmt/clippy clean, the only local failure remains the known locale golden.