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alktty/fuzz
glm-5.3-flash 58da42a021 docs: remove em dashes from repo prose and forbid them going forward
- Rewrote ~1090 em dashes across docs/ (excluding docs/reviews/
  history), README, CHANGELOG, and .opencode/agents prompts with varied
  restructures (colons, semicolons, parentheses, commas, sentence
  splits); ADR decisions, status lines, wire-shape examples, and code
  fences preserved
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Verification: cargo test; cargo clippy --all-targets -- -D warnings;
cargo fmt --check; cargo doc --no-deps; cargo test --all-features;
cargo test --manifest-path fuzz/shared/Cargo.toml; cargo check and
clippy for wasm32-unknown-unknown with -D warnings; em dash grep over
src + docs + agent prompts returns no matches outside docs/reviews/
2026-11-01 13:11:32 +00:00
..

alktty fuzzing

cargo-fuzz targets for the wire-facing parse surfaces. The design and operating rules live in docs/plans/fuzzing.md (adopted from alkcall's docs/research/fuzzing.md); this README is the operational cheat-sheet.

Layout

  • fuzz_targets/: nightly-only fuzz_target! binaries (thin wrappers).
  • shared/ is the stable-toolchain library holding the invariant logic; the corpus replay tests run here on plain cargo test.
  • corpus/<target>/ holds the committed seeds (regenerate with python3 fuzz/gen_fuzz_seeds.py).
  • artifacts/: gitignored crash/oom/timeout artifacts + campaign logs.

Targets

Target Drives
chunk_frame ChunkReader/ChunkWriter (5-byte chunk codec, ADR-001)
negotiation_frame NegotiationReader/NegotiationWriter + NegotiateRequest + error_response_bytes + the cross-codec peek-disambiguation seam
control_json ControlMessage::from_slice/to_json + signal_from_name
session_opseq the producer session pump (drive_session_pre_negotiated) + a fuzz-local mock backend: the stateful op-sequence target (ADR-004/ADR-005 invariants; the alkcall-bug-class hunt)

Running a campaign (always detached)

Agent sessions must never run fuzzing in the foreground (an OOM in a target can take down the session host; see docs/plans/fuzzing.md §3). Use the detached runner:

fuzz/run-detached.sh chunk_frame
# poll:
tail -n 50 fuzz/artifacts/chunk_frame-*.log
ls fuzz/artifacts/chunk_frame/
pgrep -f "cargo fuzz run chunk_frame"

FUZZ_RUNTIME_SECS=1800 fuzz/run-detached.sh negotiation_frame for a longer campaign. The runner pins -fork=1 -rss_limit_mb=2048 -malloc_limit_mb=2048 -timeout=25 and detaches via setsid + nohup.

Corpus replay (the standing fuzz gate)

cargo test --manifest-path fuzz/shared/Cargo.toml

Replays every committed seed through the same invariant functions the fuzzer runs, on stable, no nightly needed. Part of the release verification checklist (AGENTS.md).

Toolchain notes

rust-toolchain.toml pins nightly for this subtree only (llvm-tools required by cargo-fuzz); the crate itself stays on stable at MSRV 1.88. cargo fuzz build must be run with the fuzz dir as CWD or trust the toolchain file (rustup resolves per directory).

Run campaigns before releases and after touching src/wire.rs, src/negotiation.rs, src/control.rs, the adapter, or the session pump.

session_opseq notes

The op-sequence target is inherently slower than the byte-format targets (each input drives a full tokio session with bounded reads and yields, which means tens of exec/s per worker, not millions). That is expected: the value is state-space exploration, not throughput. It uses tokio::time::timeout internally, so the nightly target needs the --features time tokio surface already present via the shared crate's deps; no extra flags. Its invariants (kill-on-Drop, exit-chunk-is-last, sentinel/FIFO semantics) are the ones unit tests assert individually; the fuzzer explores interleavings no example test can enumerate.