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discord9
c9e7f6ca90
The node still framed its fields by hand: the grid spec's integers, a 0/1 marker for the metric name, a length prefix before every string, the tag count, a format tag, and separate length-prefixed blobs for the partial fold and the output schema, with a matching Reader on the way in. That is per-field serialization sitting inside a change whose point was to stop writing per-field serialization, and it kept the maintenance cost: any new field touched both directions, and a test located a byte by computing 8 + tree.len() + 8 + 8 + 8. One derived payload replaces it. The envelope is now a version, a payload length, and a single Postcard-encoded `FusedSeriesPayload` holding the tree, the grid spec, the binding's name/time index/tags, the output format, the statement text, the optional partial fold and the output schema. Substrait still carries the children, which are exactly the fields this format should not be inventing. `text`, `Reader` and `MAX_TAG_COUNT` are gone; the tag bound existed only because a hand-written length prefix needs one. Every carried-schema check stays: the tag-order-sensitive comparison against `state_schema(binding.tags)` for a partial export, exact equality with `series_frame_output_schema` for a frame node, and the full column-role validation for plain rows. Decode also requires the payload to be consumed exactly, so a byte appended after a valid payload is rejected rather than ignored -- `postcard::from_bytes` would have accepted it, which is why the sub-payload framing had that hole. Two tests were reading the format rather than the behaviour: The depth-limit test asserted that `RUST_MIN_STACK` was unset, but CI sets it to 8 MiB, so the assertion failed before the decoder ran and the test could never do its job there. It now runs on an explicit 2 MiB worker stack, which is the stack a normal worker has, and asserts from inside that thread that 128 nodes decode and 129 are rejected. The integration test located the embedded version by assuming an offset and comparing raw bytes. The framing change made that offset stale and it failed. It now finds the envelope, decodes the version word and asserts the number, checks the length word against the payload, and prints the observed bytes when either assertion trips. Signed-off-by: discord9 <discord9@163.com>