fix(flags): a2a streaming

[saitarun-ent]

Description

The --stream flag was only working for HTTP agent runtimes and not A2A. This PR adds back the missing arguments needed to connect the flag to invokeA2ARuntime().

Related Issue

Closes #1887

Documentation PR

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe):

Testing

How have you tested the change?

• I ran npm run test:unit and npm run test:integ
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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[Copilot]

🟡 Not ready to approve

The new A2A streaming path has correctness gaps (notably text-part format handling and bearer-token streaming behavior) and lacks targeted unit test coverage for the new message/stream branch.

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Pull request overview

This PR fixes agentcore invoke --stream for A2A runtimes by plumbing the CLI --stream flag into the A2A invoke path and adding an A2A message/stream (SSE) implementation in the AgentCore client wrapper.

Changes:

• Passes the CLI --stream option through handleInvoke() into invokeA2ARuntime().
• Extends A2AInvokeOptions with a stream?: boolean flag.
• Implements an A2A message/stream SSE response reader to yield incremental text chunks.

File summaries

File	Description
src/cli/commands/invoke/action.ts	Wires --stream into the A2A invocation options passed to invokeA2ARuntime().
src/cli/aws/agentcore.ts	Adds an A2A streaming option and SSE parsing path for message/stream.

Review details

Suppressed comments (1)

src/cli/aws/agentcore.ts:1053

• Same as the status-update path: artifact-update streaming currently only recognizes kind:'text' parts, so streamed output can be silently empty if the runtime uses type:'text' parts (which is already supported in non-streaming parsing).

                  const text = artifact.parts
                    .filter(p => p.kind === 'text' && p.text)
                    .map(p => p.text!)
                    .join('');

• Files reviewed: 2/2 changed files
• Comments generated: 3
• Review effort level: Lite

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[saitarun-ent]

Working on this.

[Copilot]

🟡 Not ready to approve

The new A2A streaming generator can drop the final SSE chunk if the stream ends without a trailing newline, which can truncate output.

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Review details

Suppressed comments (1)

src/cli/aws/agentcore.ts:1092

• a2aStreamGenerator drops any trailing partial SSE line when the stream ends without a final \n, because buffer is never processed after the read loop. This can truncate the last chunk (the other streaming helpers in this file explicitly process the remaining buffer before releasing the reader lock).

      }
    } finally {
      reader.releaseLock();
    }

• Files reviewed: 4/4 changed files
• Comments generated: 0 new
• Review effort level: Lite

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[Copilot]

🟡 Not ready to approve

There are correctness and test-suite stability issues (decoder flush on streaming, fragile test cleanup, and a missing mocked export that can break existing tests) that should be addressed before merging.

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Review details

Suppressed comments (2)

src/cli/aws/tests/agentcore-a2a-bearer.test.ts:203

• afterEach unconditionally calls fetchSpy.mockRestore(), but fetchSpy is only assigned inside mockFetchStream. If a test throws before calling mockFetchStream (or a future test forgets), the cleanup hook will throw and can mask the real failure.

  afterEach(() => {
    fetchSpy.mockRestore();
    vi.clearAllMocks();
  });

src/cli/aws/agentcore.ts:1102

• TextDecoder.decode(..., { stream: true }) should be flushed after the read loop; otherwise a final multi-byte UTF-8 codepoint split across chunks can be dropped/corrupted when the stream ends.

      if (buffer) {
        yield* parseDataLine(buffer);
      }

• Files reviewed: 4/4 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

🟡 Not ready to approve

The bug fix is correct in code, but it lacks a unit test that specifically asserts the --stream flag wiring selects invokeA2ARuntimeStreaming() for A2A, which risks regression.

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Review details

Suppressed comments (2)

src/cli/commands/invoke/action.ts:600

• The new A2A --stream branching is a key bug fix, but there is no unit test coverage in the invoke command tests that verifies options.stream routes to invokeA2ARuntimeStreaming() (and not invokeA2ARuntime()). Adding a targeted test here would prevent future regressions of the flag wiring.

      const a2aResult = options.stream
        ? await invokeA2ARuntimeStreaming(a2aOpts, options.prompt)
        : await invokeA2ARuntime(a2aOpts, options.prompt);

src/cli/aws/agentcore.ts:1036

• This A2A SSE parsing / text extraction logic duplicates the existing, tested A2A SSE helpers in src/cli/operations/dev/invoke-a2a.ts (e.g., extractSSEEventText() and its streamedFromStatus de-dupe behavior). Keeping two implementations increases the risk they diverge as the A2A event schema evolves; consider extracting a shared helper module used by both call sites.

  async function* a2aStreamGenerator(
    reader: ReadableStreamDefaultReader<Uint8Array>
  ): AsyncGenerator<string, void, unknown> {
    const decoder = new TextDecoder();
    let buffer = '';
    let streamedFromStatus = false;

• Files reviewed: 5/5 changed files
• Comments generated: 0 new
• Review effort level: Lite

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[Copilot]

🟢 Ready to approve

The change is localized, correctly wires the --stream flag for A2A, and includes focused unit tests covering the new routing and streaming behavior.

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Review details

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Lite

We're testing this review assessment. Please use 👍 or 👎 to tell us if it's correct.