feat(rivetkit-agent-os): phase 2 — stat action arm + structured-payload wrapper tests for cross-encoding parity

[abcxff]

No description provided.

[abcxff]

Stack for rivet-dev/rivet

• feat(rivetkit-agent-os): phase 3 process — 11 arms (exec/spawn/wait/kill/stop/list/all/tree/get/writeStdin/closeStdin) + ExecResultDto #5197 unkrsszt · 2026-06-08 18:29:29
• test(rivetkit-agent-os): partial-failure driver test for readFiles batch DTO (Option<content>, Option<error>) #5196 pzzzpmtr · 2026-06-08 18:29:28
• feat(rivetkit-agent-os): phase 3 filesystem — mkdir/readdir/exists/move/deleteFile/readFiles/writeFiles/readdirRecursive arms + batch DTOs #5195 onyykwlk · 2026-06-08 18:29:27
• test(rivetkit-agent-os): config parsing tests + documented JS↔Rust software shape mismatch (phase 3 prep) #5194 ouyvrlxt · 2026-06-08 18:29:26
• feat(rivetkit-agent-os): phase 2 — stat action arm + structured-payload wrapper tests for cross-encoding parity #5193 slkvonmt · 2026-06-08 18:29:25 👈
• feat(rivetkit): phase 1c — agentOs() native ladder + engine driver branch + driver-suite e2e green #5192 nxzrussy · 2026-06-08 18:29:24
• feat(rivetkit-napi): phase 1b — NapiActorFactory.fromAgentOs static constructor + writeFile arm + e2e factory round-trip #5191 mtlnunov · 2026-06-08 18:29:22
• feat(rivetkit-agent-os): phase 1a — rust crate skeleton + readFile arm + dispatcher e2e against real sidecar #5190 wrxkrssv · 2026-06-08 18:29:21
• feat(rivetkit): JSON_COMPAT_UINT8_ARRAY byte-payload encoding parity with TS (encode + decode + cross-language tests) #5189 ukssumln · 2026-06-08 18:29:20
• chore: phase 0 prereqs (rivetkit workspace member, serde_bare align, wasm skip.agentOs default) #5188 qvnkvkxw · 2026-06-08 18:29:19
• docs: PLAN2 + TODOLIST + RIVETKIT_RUST_FIX (clean slate, post-wipe) #5187 yqrwozvn · 2026-06-08 18:29:18
• main

Check out this stack: forklift get https://github.com/rivet-dev/rivet/pull/5193
Pull/update this stack: forklift sync
Publish local edits: forklift submit
Merge when ready: forklift merge

[claude]

Code Review### OverviewThis PR adds the stat filesystem action to the agent-os action dispatcher and introduces cross-encoding parity tests for structured (non-byte) payloads modeled after VirtualStat. The action implementation is clean and the test coverage strategy is sound.### IssuesWeak ino u64 overflow test. Both the Rust roundtrip and TS parity tests note that ino must not silently truncate to f53, yet use 9_876_543_210 which is safely representable in f64 (2^53 is roughly 9 quadrillion, so this value is about 6 orders of magnitude below the danger zone). The test passes for the wrong reason: the encoder could silently downcast to f64 and these assertions would still be green. Use a value above 2^53 to actually exercise the invariant, e.g. 9_007_199_254_740_993 (2^53 + 1) or 18_000_000_000_000_000.Struct duplication between test files. VirtualStatFixture (in encoding_fixtures.rs) and the inline VirtualStat (in encoding_roundtrip.rs) are nearly identical 15-field structs. Defining them once in a shared test helper, or importing agent_os_client::VirtualStat directly if it derives Serialize, would eliminate the drift risk. As-is, a field added to the real VirtualStat requires three parallel updates.virtual_stat.json missing trailing newline. The fixture file is committed without a terminal newline. Minor but consistent repo convention.Phase 2 comments will rot. Per repo convention, delta-context comments like Phase 2 gate are ephemeral - future readers will not know what Phase 2 was. Strip the phase framing; the behavior is self-evident from the assertion names.### Nits- Em dash in filesystem.rs doc comment. CLAUDE.md says not to use em dashes; separate with a period instead. The existing readFile comment has the same issue but should not be propagated.- is_symbolic_link is false in the fixture test and true in the roundtrip test. Independent tests so not a correctness issue, but aligning avoids confusion when cross-referencing.- The TS test comment says Rust encode to TS decode path losslessly but the fixture is loaded as pre-decoded JSON, so the CBOR leg is covered by the Rust fixture generator, not the TS test. Worth clarifying inline.### SummaryThe action wiring (stat arm in dispatch, filesystem::stat helper) is correct and follows existing patterns. Main ask before merge: fix the ino test value so the u64-precision assertion actually exercises the invariant it claims to cover.