wave 7: fuzz sidecar scaffold (fuzz/ workspace, shared crate, runner, dict, seeds skeleton)

tasks/fuzz-scaffold.md

@@ -1,7 +1,7 @@
 ---
 id: fuzz-scaffold
 name: Fuzz sidecar scaffold — `fuzz/` workspace, runner, dict, seed generator, shared-crate skeleton
-status: pending
+status: completed
 depends_on: []
 scope: moderate
 risk: low
@@ -67,26 +67,31 @@ Toolchain prerequisites verified present in the dev environment
 
 ## Acceptance Criteria
 
-- [ ] `fuzz/` exists with the §2 layout: sidecar `Cargo.toml` (own
+- [x] `fuzz/` exists with the §2 layout: sidecar `Cargo.toml` (own
       `[workspace]`, `publish = false`), `rust-toolchain.toml`
       (nightly + llvm-tools-preview), `shared/` crate, `run-detached.sh`
       (executable), `json.dict`, `gen_fuzz_seeds.py`, `README.md`,
       `fuzz/.gitignore`
-- [ ] `fuzz/shared` compiles and tests green on **stable** via
+- [x] `fuzz/shared` compiles and tests green on **stable** via
       `cargo test --manifest-path fuzz/shared/Cargo.toml` (the gate
       command works from the wave's first task onward)
-- [ ] `cargo fuzz build` succeeds from `fuzz/` (nightly selected by the
-      pin; zero targets yet is acceptable if cargo-fuzz tolerates it —
-      otherwise a placeholder target documents the check; record which)
-- [ ] Root workspace unaffected: `cargo build` / `cargo test` /
+- [x] `cargo fuzz build` succeeds from `fuzz/` (nightly selected by the
+      pin; **cargo-fuzz does NOT tolerate zero targets** here — a
+      bins-only package with no `[[bin]]` fails manifest parse, which
+      also blocks the shared gate's workspace discovery; a placeholder
+      target `fuzz_targets/placeholder.rs` documents the check and is
+      replaced by the wave-1 target tasks — recorded, as this AC asked)
+- [x] Root workspace unaffected: `cargo build` / `cargo test` /
       `clippy -D warnings` / `fmt --check` green from the root, and the
       root toolchain is still stable (the pin did not leak upward)
-- [ ] `exclude = ["fuzz"]` present on the root `[workspace]` table
-- [ ] `run-detached.sh` is byte-identical to alksocks' modulo the
-      usage-line naming (no behavior drift)
-- [ ] `shared` is not referenced by any workspace crate manifest
-      (wasm posture intact: `cargo check --target
-      wasm32-unknown-unknown -p alkstore-mem` still clean)
+- [x] `exclude = ["fuzz"]` present on the root `[workspace]` table
+- [x] `run-detached.sh` is byte-identical to alksocks' modulo the
+      usage-line naming (`cmp` clean — the usage line is already
+      repo-agnostic, so no diff at all)
+- [x] `shared` is not referenced by any workspace crate manifest
+      (only the root's `exclude = ["fuzz"]` mentions fuzz at all;
+      `cargo check --target wasm32-unknown-unknown -p alkstore-mem`
+      clean)
 
 ## References
 
@@ -99,8 +104,53 @@ Toolchain prerequisites verified present in the dev environment
 
 ## Notes
 
-> To be filled by implementation agent
+- **Zero targets are NOT tolerated by cargo-fuzz / cargo here** — the
+  AC's "if tolerated" branch failed: a bins-only package with no
+  `[[bin]]` entries cannot manifest-parse ("no targets specified"),
+  and that parse failure also breaks the shared gate's workspace
+  discovery (`cargo test --manifest-path fuzz/shared/Cargo.toml`
+  resolves the workspace root at `fuzz/`). Placeholder route taken
+  (as the AC's otherwise-branch prescribed): `fuzz_targets/placeholder.rs`
+  — a minimal `fuzz_target!` stub with a doc comment saying the wave-1
+  target tasks replace it — plus its `[[bin]]` entry in `fuzz/Cargo.toml`.
+- **Repo-layout substitution beyond naming:** alksocks has its package
+  at the repo root (`alksocks = { path = "../.." }`); alkstore is the
+  ADR-001 workspace split, so the core crate sits in the `alkstore/`
+  subdir — shared's dep is `alkstore = { path = "../../alkstore" }`
+  and the fuzz package's is `path = "../alkstore"`.
+- **`json.dict`** is byte-identical across alkcall / alktunnels /
+  alksocks (md5-verified), so it was copied verbatim (alkcall-envelope
+  tokens). Whether any alkstore-specific tokens should be added is a
+  target-task concern, not scaffold scope.
+- `fuzz/Cargo.lock` is committed (alksocks pattern); generated
+  fresh — alksocks' lock is not portable across dep sets.
+- `arbitrary_value.rs` copied verbatim except one intra-comment stale
+  reference: alksocks' `envelope_frame` → "the payload targets".
+- `fuzz/.gitignore` has no `!corpus/<target>` negation lines yet —
+  each target task adds its own when its corpus lands (task spec).
+- `gen_fuzz_seeds.py` is the plumbing-only skeleton (`seed_name` /
+  `write_seed`, empty `main()` registry); runs clean as a no-op.
 
 ## Summary
 
-> To be filled on completion
+Landed the wave-7 scaffold: `fuzz/` sidecar workspace
+(`alkstore-fuzz`, `publish = false`, own `[workspace]`, libfuzzer-sys +
+path-dep shared crate) with `rust-toolchain.toml` pinning
+nightly + llvm-tools-preview inside `fuzz/` only; stable-toolchain
+`fuzz/shared` (`alkstore-fuzz-shared`) with the quinn-CI-pattern crate
+doc and the alksocks `arbitrary_value.rs` `JsonValue` bounded-depth
+helper; `run-detached.sh` (byte-identical to alksocks', executable);
+`json.dict`; `gen_fuzz_seeds.py` skeleton; `.gitignore` (no corpus
+negations yet); `README.md` skeleton; `exclude = ["fuzz"]` on the root
+workspace; and the placeholder fuzz target so the toolchain check and
+the shared gate work before the real targets land.
+
+Verified: `cargo test --manifest-path fuzz/shared/Cargo.toml` green on
+stable from the root; `cargo fuzz build` green from `fuzz/` (nightly
+pin selected; placeholder + shared + alkstore compile under ASAN);
+shared clippy `-D warnings` + `fmt --check` green; root `cargo build` /
+`cargo test` (all suites pass) / clippy `-D warnings` / `fmt --check`
+green with the stable toolchain still active at the root (rustc 1.99.0
+stable; no upward pin leak); `cargo check -p alkstore-mem --target
+wasm32-unknown-unknown` clean; no workspace manifest references
+`alkstore-fuzz-shared` (only the root `exclude` mentions `fuzz`).