ymm-oss/fsl

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AI-Native Formal Specification Language — a bounded model checker (Lark + Z3) built for LLM write/verify/repair loops.

Stars: 27
Forks: 4
Open beginner issues: 5
Indexed issues: 147
Avg merge: 4h 42m
Merged PRs (30d): 114

Dominant language: Rust
License: Apache-2.0
Last GitHub push: Sep 17, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: No code of conduct
Beginner labels: No beginner labels indexed

Beginner friendly Everything

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147 open issues indexed

[Draft] roadmap: ship the Agent Skills through a signed packslip, and make mise a first-class route Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

ymm-oss/fsl#1082 · Opened Sep 18, 2026
[ruleset drift] main safety and CI diverged from .github/ruleset-contract.json Open

ci/ruleset-drift

Difficulty 3/5 1-2 days Newbie friendliness 64/100

ymm-oss/fsl#1081 · 4 comments · Opened Sep 17, 2026
fix(sweep): a sound spec with any `reachable` always reports `sweep_failed`, because `insufficient_depth` cells count as counterexamples Open

Difficulty 3/5 1-2 days Newbie friendliness 75/100

ymm-oss/fsl#1080 · 1 comment · Opened Sep 17, 2026
meta(agents): gate the AGENTS.md / repository-contract split that #1073 verified by hand Open

Difficulty 3/5 1-2 days Newbie friendliness 72/100

ymm-oss/fsl#1077 · Opened Sep 17, 2026
fslc-lsp has no way to report its version, so an installed language server cannot be identified Open

Difficulty 3/5 1-2 days Newbie friendliness 76/100

ymm-oss/fsl#1074 · Opened Sep 16, 2026
test: issue_250 fixture roots collide the same way #1061 did (domain_expand_source reaches 3 tests with one name) Open

bug

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

ymm-oss/fsl#1069 · Opened Sep 16, 2026
fix(kernel): `kernel` skips `validate_db`, so it accepts a dbsystem document `check` rejects Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#1059 · Opened Sep 15, 2026
design(spec-domains): two accepted documents disagree on whether an undeclared `values` name is rejected Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#1058 · Opened Sep 15, 2026
WASM lane reads `from \"…\"` inside an .fsl comment as an import and fails with ENOENT Open

Difficulty 3/5 1-2 days Newbie friendliness 65/100

ymm-oss/fsl#1056 · Opened Sep 15, 2026
No gate exercises the claims corpus's deep properties, its property-free saga, or its edit-site rationales Open

Difficulty 5/5 Over a week Newbie friendliness 42/100

ymm-oss/fsl#1055 · Opened Sep 15, 2026
observability: an unwritable cache root silently disables verify caching Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ymm-oss/fsl#1054 · Opened Sep 15, 2026
design(runtime): two explicit-state searches, only one of them bounded by size Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#1050 · Opened Sep 15, 2026
test(corpus): the Verdict Conservation Law sweeps check and verify but not diff Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#1049 · Opened Sep 15, 2026
hooks: cargo_lock.py's Git-common-dir lock is unreachable from a sandboxed linked worktree, blocking cargo and herdr alike Open

Difficulty 5/5 Over a week Newbie friendliness 38/100

ymm-oss/fsl#1046 · 1 comment · Opened Sep 15, 2026
test(fifo): cleanup loop unwraps the writer outcome on a race with is_finished(), reddening required lanes Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 76/100

ymm-oss/fsl#1040 · 1 comment · Opened Sep 15, 2026
docs(ledger): ledger.rs:514 cites a `classify_source` section that #996 removes Open

bug

Difficulty 1/5 Under an hour Newbie friendliness 84/100

ymm-oss/fsl#1037 · Opened Sep 14, 2026
meta(ci): native Z3 4.16 (windows-latest) の 60分予算は余裕27%で、同一内容の再実行が61m/44mと振れて打ち切られた Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#1025 · Opened Sep 9, 2026
verify(cache): seam の verdict を cache に入れるかの判断を確定する（#1002 で reachable になった2値） Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ymm-oss/fsl#1022 · 2 comments · Opened Sep 9, 2026
html(report): status_class の catch-all が未知の verdict を中立バッジにする（#1002 で impl_violated が初めて到達した） Open

ai-discovered bug

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#1021 · 1 comment · Opened Sep 9, 2026
test(parity): check_rust_full_envelope.py が母集団 43/43 で落ち、実在の差分1件を覆っている Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ymm-oss/fsl#1019 · Opened Sep 9, 2026
fix(cli): unreferenced_requirement の hint が typed annotation と init を名指ししていない Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#1017 · Opened Sep 8, 2026
test(parity): #94 acceptance test pins only the frozen Python reference, not the native CLI Open

ai-discovered bug

Difficulty 3/5 1-2 days Newbie friendliness 68/100

ymm-oss/fsl#1010 · Opened Sep 7, 2026
design(verify): define inline implements semantics for --property, --exclude-properties, and --from-state Open

ai-discovered bug

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#1008 · Opened Sep 7, 2026
test(site): strip_js_comments の状態遷移ごとの境界 control が不足している（必須 context が依存する手書きパーサ） Open

ai-discovered

Difficulty 3/5 1-2 days Newbie friendliness 68/100

ymm-oss/fsl#1006 · 1 comment · Opened Sep 7, 2026
fix(diagnostics): no_user_invariants が「implicit type bounds しか検査していない」と偽って報告する（同一 envelope に leads_to / reachables が入っている） Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#1004 · Opened Sep 7, 2026
fix(examples): 旗艦 e2e chain の README が凍結 Python (.venv/bin/python -m fslc) を権威として教え、逐語 assert がそれを固定している Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#999 · Opened Sep 7, 2026
fix(examples): --deadlock ignore を教える実行例が examples 配下の12ファイル・36箇所に残っている（#979 の e2e 以外の全数） Open

ai-discovered bug

Difficulty 4/5 3-5 days Newbie friendliness 42/100

ymm-oss/fsl#998 · Opened Sep 7, 2026
spike(evidence-binding): 最初の producer/consumer を1組決め、必要な artifact binding と証跡帰属の粒度を逆算する Open

needs-evidence spike

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#994 · 1 comment · Opened Sep 7, 2026
docs(refine): chain の隣接検査と直接合成検査を同値とする記述を直す Open

ai-discovered documentation

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#991 · 1 comment · Opened Sep 6, 2026
docs(RUST-PORTING): decide the fate of check_rust_full_envelope.py's frozen-Python comparison edge Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

ymm-oss/fsl#988 · 1 comment · Opened Sep 4, 2026
perf(ci): evaluate trimming debug info to shrink the semantic-mutation / rust-native-z3 Actions caches Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#984 · Opened Sep 4, 2026
fix(codex): cargo_lock.py reports a signalled shell as 247 instead of the POSIX 128+N Open

Difficulty 2/5 1-3 hours Newbie friendliness 86/100

ymm-oss/fsl#983 · Opened Sep 4, 2026
fix(e2e): 旗艦 e2e chain の公開手順が不要な --deadlock ignore を教えており、逐語 assert がそれを固定している Open

ai-discovered bug

Difficulty 3/5 1-2 days Newbie friendliness 72/100

ymm-oss/fsl#979 · 1 comment · Opened Sep 3, 2026
docs(docs-site): Playground の verify 経路をローカルで検証できない(docs/intro/fsl-wasm/ のビルド前提が未文書化) Open

ai-discovered

Difficulty 1/5 1-3 hours Newbie friendliness 88/100

ymm-oss/fsl#977 · Opened Sep 3, 2026
test(tooling): require invocation-unique scratch roots with ownership-checked cleanup Open

Difficulty 5/5 Over a week Newbie friendliness 38/100

ymm-oss/fsl#963 · Opened Sep 1, 2026
meta(test-quality): 検出器・比較・inventory の false green を fail closed にする Open

Difficulty 5/5 Over a week Newbie friendliness 32/100

ymm-oss/fsl#956 · Opened Aug 30, 2026
meta(mutation): 実装 mutation testing の accepted pilot を verify_bounded_config の leadsTo 3 decision へ拡張する Open

Difficulty 4/5 3-5 days Newbie friendliness 68/100

ymm-oss/fsl#953 · Opened Aug 30, 2026
docs(agents): 「投入した」を「実行した」と報告する誤りと、コミット前の hunk 分類を AGENTS.md の規則にする Open

documentation

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

ymm-oss/fsl#948 · Opened Aug 28, 2026
design(cli): verify の result クラス↔process exit 対応が単一オーナーを持たず、テスト側の束縛強度に依存している Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#901 · 1 comment · Opened Aug 25, 2026
design(lints): deny clippy::expect_used/unwrap_used in library crates to block panics crossing the public API boundary Open

Difficulty 5/5 Over a week Newbie friendliness 45/100

ymm-oss/fsl#899 · Opened Aug 25, 2026
docs(case-study): property-first 分散leaseモデルから実装回帰テストまでを示す Open

ai-discovered documentation track:D

Difficulty 5/5 Over a week Newbie friendliness 45/100

ymm-oss/fsl#887 · Opened Aug 24, 2026
design(language): 環境仮定を保証から分離し、runtime evidence に結び付ける Open

ai-discovered enhancement spike track:E

Difficulty 5/5 Over a week Newbie friendliness 28/100

ymm-oss/fsl#886 · Opened Aug 24, 2026
内部表現が「公開契約で既に閉じている集合」を型に載せていない（演算子 `String`、`KernelModel` の外部構築） Open

ai-discovered enhancement

Difficulty 5/5 Over a week Newbie friendliness 45/100

ymm-oss/fsl#859 · Opened Aug 21, 2026
spike(corpus): accepted surface syntax のゼロ使用箇所を positive/negative control または明示的非対象へ分類する Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#849 · Opened Aug 20, 2026
`fslc testplan`: bounded exhaustive conformance vector から実装テストを選択・生成する（negative 271件が現在未使用） Open

ai-discovered enhancement

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#844 · Opened Aug 20, 2026
到達状態では決して偽にできない guard 節を depth 非依存で検出する（`validation` 宣言 + 帰納 lane） Open

ai-discovered enhancement

Difficulty 5/5 Over a week Newbie friendliness 35/100

ymm-oss/fsl#842 · Opened Aug 20, 2026
fsl-lsp: some COMPLETION_KEYWORD_EXCLUSIONS members sit in a group whose stated reason does not describe their grammar role Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ymm-oss/fsl#838 · Opened Aug 20, 2026
meta(ci): the cache budget audit cannot distinguish reclaimable superseded duplicates from genuine growth, so recovery diagnosis stays manual Open

Difficulty 4/5 3-5 days Newbie friendliness 56/100

ymm-oss/fsl#835 · 9 comments · Opened Aug 19, 2026
docs(vscode): the documented .vsix asset name is versioned, but releases publish an unversioned fsl-vscode.vsix Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

ymm-oss/fsl#828 · Opened Aug 19, 2026
model.rs: source_origin()'s hardcoded inline-initializer metadata is reused for annotation-validation errors Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

ymm-oss/fsl#820 · Opened Aug 18, 2026

ymm-oss/fsl

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