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fix(canvas): revert v1 outbound file part shape

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The previous PR (#2509) flipped canvas outbound file parts to the v1
flat shape `{url, filename, mediaType}` based on a hypothesis that
a2a-sdk's JSON-RPC parser silently dropped v0 `{kind:"file", file:{...}}`
shapes. Live test shows the opposite: a2a-sdk's JSON-RPC layer
validates against the v0 Pydantic discriminated union (TextPart |
FilePart | DataPart), so v1 flat shape is rejected with:

    Invalid Request:
      params.message.parts.0.TextPart.text — Field required
      params.message.parts.0.FilePart.file — Field required
      params.message.parts.0.DataPart.data — Field required

The actual root cause of the user-visible "Error: message contained
no text content" was the missing `/workspace` chown (CP PR #381 +
test pin #382), not a wire-shape mismatch. Verified end-to-end by
sending a v0 image-only message after PR #381 + workspace re-provision
— agent receives the file, reads its bytes, and replies normally.

Reverting only the canvas outbound shape. Defensive v1-tolerance
stays in:
  - workspace/executor_helpers.py — extract_attached_files still
    accepts v1 protobuf parts in case a future client emits them or
    a future SDK release flips internal representation. Harmless on
    the v0 hot path.
  - canvas/message-parser.ts — extractFilesFromTask still tolerates
    v1 shape on incoming agent responses. Some agents may emit v1
    when their internal serializer round-trips through protobuf.

Tests stay green (91 canvas, 86 workspace).
This commit is contained in:
Hongming Wang 2026-05-02 01:31:56 -07:00
parent bf83af0960
commit 3ce7c11a13
1 changed files with 28 additions and 25 deletions
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53
canvas/src/components/tabs/ChatTab.tsx
View File

@ -32,23 +32,19 @@ interface A2AFileRef {
bytes?: string;
size?: number;
}
// A2A Part shape — covers both v0 (Pydantic discriminated union with
// `kind: "text" | "file"`) and v1 (a2a-sdk protobuf with flat fields:
// `text` for text parts; `url` + `filename` + `mediaType` for file
// parts; no `kind` discriminator at all). Outbound we now send v1 for
// file parts because the v1 protobuf parser drops the v0 keys via
// `ignore_unknown_fields=True`, surfacing as the user-visible
// "Error: message contained no text content" on image-only chats
// (2026-05-01 hongming incident). Text parts stay accident-compatible
// across v0/v1 because the field name is `text` in both.
// A2A Part — outbound matches the v0 Pydantic discriminated-union
// shape that a2a-sdk's JSON-RPC layer validates against (TextPart |
// FilePart | DataPart). The v1 flat-protobuf shape `{url, filename,
// mediaType}` is internal SDK serialization only; sending it on the
// wire fails Pydantic validation with `TextPart.text required,
// FilePart.file required, DataPart.data required` and never reaches
// the executor. Inbound also tolerates the v1 shape via
// message-parser.ts since the agent itself may serialize as v1 in
// some downstream tools.
interface A2APart {
kind?: string;
kind: string;
text?: string;
file?: A2AFileRef;
// v1 file-part fields (flat — no nested `file` object):
url?: string;
filename?: string;
mediaType?: string;
}
interface A2AResponse {
result?: {
@ -516,21 +512,28 @@ function MyChatPanel({ workspaceId, data }: Props) {
// A2A parts: text part (if any) + file parts (per attachment). The
// agent sees both in a single turn, matching the A2A spec shape.
//
// File parts use the v1 protobuf shape (flat `url`/`filename`/
// `mediaType`) because the workspace runtime's v1 parser drops
// the legacy v0 `{kind:"file", file:{...}}` shape via
// `ignore_unknown_fields=True`. Sending v0 → empty Part →
// empty attachments → "Error: message contained no text content"
// on image-only chats (2026-05-01 hongming). Text parts keep the
// shared `{kind:"text", text}` shape because `text` is a field
// in both v0 and v1.
// File parts use the v0 discriminated-union shape `{kind:"file",
// file:{...}}` because that's what a2a-sdk's JSON-RPC layer
// validates against (`SendMessageRequest.params.message.parts[]`
// → `TextPart | FilePart | DataPart` Pydantic union). Sending the
// v1 flat shape `{url, filename, mediaType}` returns
// `Invalid Request — TextPart.text required, FilePart.file
// required, DataPart.data required` and the message never
// reaches the executor. v1 protobuf is internal serialization
// only; the wire shape stays v0 until the SDK migrates the
// JSON-RPC schema. Text parts keep `{kind:"text", text}` for the
// same reason.
const parts: A2APart[] = [];
if (text) parts.push({ kind: "text", text });
for (const att of uploaded) {
parts.push({
url: att.uri,
filename: att.name,
mediaType: att.mimeType,
kind: "file",
file: {
name: att.name,
mimeType: att.mimeType,
uri: att.uri,
size: att.size,
},
});
}