[Nic-dorman]

Summary

Follow-up to #313 (review note 2): a gRPC range request that starts at or past the end of the object now tells the caller how big the object is, as REST already does.

• REST answers 416 with Content-Range: bytes */size. antd-go puts it in RangeNotSatisfiableError.Size.
• gRPC returned OUT_OF_RANGE with the size only in the message text, so antd-go set Size: -1.

Stacked on #313. The base is nic/v2-1425-antd-byte-range-download, so the diff is this change only. Merge after #313. If #313 is merged with a merge commit, GitHub retargets this PR to main once that branch is deleted.

What changes

• Daemon (antd/src/error.rs): AntdError::RangeNotSatisfiable → tonic::Status::out_of_range now carries x-content-range: bytes */<size> metadata. That's the same value as REST's header and the same key the success path already uses. tonic sends it in the trailers-only response; the message text is unchanged.
• antd-go (grpc_client.go): reads that trailer on both ways a ranged stream can fail before its first frame: an error from Header(), or a trailers-only response whose status comes from Recv(). A daemon without this change sends no trailer, so Size stays -1.

The data.proto comment on the range fields isn't updated here. Changing it would mean regenerating the Go/Swift/Rust stubs and the Kotlin copy for a comment. The key is documented on the antd-go error type and at the daemon mapping; it can go into the proto next time data.proto changes.

Compatibility

Additive. Old clients ignore the extra metadata. New antd-go against an old daemon gets Size: -1, exactly as before.

Test evidence

Unit tests:

• antd: 111 pass. range_not_satisfiable_is_grpc_out_of_range now asserts the metadata.
• antd-go: all pass. The mock daemon sends the trailer, and an old-daemon key doesn't. TestGrpcDataStreamRangeOutOfRange checks Size 6 (private) and 5 (public), and -1 for the old daemon.
• fmt, clippy -D warnings and go vet are clean.

Devnet: On a 25-node devnet with a 4.5 GiB object (4,831,850,553 bytes), using a daemon built from this branch, the #313 range check passes (ALL PASS). This time it also requires the object size on gRPC.

• A gRPC stream request at offset = size returns OUT_OF_RANGE, and antd-go's RangeNotSatisfiableError.Size is 4,831,850,553, matching REST's 416.
• In the same run, antd-rust's range methods (feat(antd-rust): byte-range stream methods on the REST and gRPC clients #317) read the size from this metadata over gRPC: RangeNotSatisfiable { size: Some(4831850553) }.
• The rest of feat(antd): byte-range downloads on the data streams (REST, gRPC, antd-go) #313's run is unchanged: 38 ranges byte-identical across REST and gRPC, and only overlapping chunks fetched. antd logged no ERROR or WARN lines.

🤖 Generated with Claude Code

[dirvine]

Six-seat independent review panel — PR #316 (gRPC OUT_OF_RANGE carries object size)

Reviewed head: 13c2795731d5a831b506663b2f62491e5029513f (branch → base nic/v2-1425-antd-byte-range-download, stacked on #313). 4 files, +62/−11. CI on this head: all green (Check antd, antd-rust, antd-js, Lint + Test antd-go, security audit).

Summary

Daemon-side, AntdError::RangeNotSatisfiable { size } now maps to tonic::Status::out_of_range with x-content-range: bytes */<size> metadata — the exact value REST's 416 already puts in Content-Range. antd-go reads that trailer in a new rangeStreamError helper on both pre-first-frame failure paths (Header() error, and trailers-only status surfaced by Recv()); a daemon without the trailer leaves Size: -1 as before. Message text unchanged; no .proto touched (comment-only regen deferred, documented in the PR body). All six seats found no blocking defects.

Per-seat verdicts

Seat	Tool	Verdict	Key findings
1	gpt-5.1-codex (via OpenRouter)	APPROVE	Mapping correct; .expect() safe (u64 renders as ASCII digits); test pins the metadata
2	gpt-5.1-codex (via OpenRouter)	APPROVE	Both failure paths wrapped; errorFromGrpc returns a fresh *RangeNotSatisfiableError per call, so mutation is safe; no findings
3	gpt-5.1-codex (via OpenRouter)	APPROVE	Key/value valid as gRPC metadata (lowercase key, ASCII, short value); no initial-metadata/trailer collision (different phases of the same RPC)
4	gpt-5.1-codex (via OpenRouter)	APPROVE	Test coverage solid (Size 6 private, 5 public, −1 old-daemon); suggests a malformed-trailer edge test
5	gpt-5.1-codex (via OpenRouter)	APPROVE	Additive compatibility verified; REST/gRPC parity holds; proto-comment omission reasonable
6	GLM-5.2 (OpenRouter, independent model seat)	APPROVE	Implicit pointer-aliasing comment suggestion; defensive strings.HasPrefix guard before parseContentRange (future-proofing, unreachable today); debug_assert! instead of expect (optional)

Dissent: none. All six seats approve.

Blocking issues

None.

Non-blocking findings (deduplicated)

1. Malformed-trailer edge test (seat 4) — a unit test where the trailer is present but not parseable (unsatisfiedSize → −1) would pin the fallback path in rangeStreamError directly; the "old-daemon" test only covers the absent-trailer case. antd-go/range_test.go:193-208.
2. Defensive guard before parseContentRange (seat 6) — if a future grpc-go ever surfaced trailers-only metadata via Header(), the bytes */size value would feed the success-path parser and yield a generic malformed error instead of *RangeNotSatisfiableError. Unreachable with current grpc-go; optional. antd-go/grpc_client.go:434.
3. Implicit pointer aliasing (seat 6) — rangeStreamError mutates rerr.Size on the pointer returned by errorFromGrpc; correct today (fresh allocation per call), a one-line comment would aid future readers. antd-go/grpc_client.go:449-464.
4. expect → debug_assert (seat 6, judgement call) — the metadata-value .expect() is provably safe for u64 rendering; not worth changing.

Claim checks (highlights)

• Both pre-first-frame failure paths read the trailer — verified. openGrpcRange wraps the Header() error path and the trailers-only Recv() path with rangeStreamError; Trailer() is available once the RPC has terminated with a status. antd-go/grpc_client.go:423-464.
• Old daemon → Size: -1 — verified. errorFromGrpc seeds Size: -1; the trailer only overrides when present; the old-daemon mock test asserts −1. antd-go/grpc_client.go:173, antd-go/range_test.go:197-208.
• Same key/value as REST — verified. bytes */{size} matches the REST 416 Content-Range construction in antd/src/error.rs:204-209; the success path already uses x-content-range in initial metadata, so the key is consistent across the RPC lifecycle.
• Message text unchanged — verified. e.to_string() still feeds the status message.
• No proto change — verified. The diff touches exactly 4 files; no .proto in it.
• Test/CI/devnet claims — CI on head 13c2795 is green (checked live); the 25-node devnet run is the PR author's report and was not re-executed by the panel.

Limitations

• Seats ran static inspection (no local builds/tests); execution evidence is the CI run on this exact head.
• The devnet evidence (4.5 GiB object, gRPC Size 4,831,850,553 matching REST) is the PR body's report, not independently reproduced.

Verdict

APPROVE — no blocking issues; four non-blocking follow-ups, none worth blocking the merge.