feat(stream): return StreamResult from stream helpers; fix _compat SyntaxError

[windsornguyen]

Pull Request

Linear Issue

N/A

Summary

What:

stream_async and stream_sync now accumulate content and tool-call deltas into a StreamResult dataclass and return it instead of None. A shared accumulate_tool_call() function is extracted so both the stream helpers and DedalusRunner use the same logic. Also fixes a duplicate by_alias keyword arg SyntaxError in _compat.py that broke Python 3.9.

Why:

Streaming callers previously had no way to programmatically access accumulated content or tool calls after a stream completed — the helpers were fire-and-forget printers. The _compat.py bug blocked all test execution on Python 3.9.

Lines added: ~0 net (+774 / −778 — mostly test style normalization)

Test Plan

• uv run pytest tests/test_stream_helpers.py — 14 tests covering content accumulation, incremental tool-call reassembly (including thought_signature, parallel calls), empty streams, and result independence.
• uv run pytest tests/test_encryption.py tests/test_mcp_wire.py tests/test_mcp_wire_connections.py tests/test__bug_report.py tests/test_local_scheduler.py — 85 existing hand-written tests still pass after style refactor.

Repro / Showcase

N/A — no UI change. The _compat.py fix is verified by successfully importing dedalus_labs on Python 3.9.

Tests Added

• Unit tests
• Integration tests
• E2E tests
• N/A (no new code paths)

Documentation

• Internal (docs/): N/A
• External (apps/docs/): N/A

Reviewers

• Domain: @
• Readability: @

Notes for Reviewers

Three commits:

1. fix(_compat) — one-line deletion of duplicate by_alias=True
2. feat(stream) — StreamResult, accumulate_tool_call, updated helpers, DRY refactor of DedalusRunner, new tests
3. style(tests) — flatten class-based tests to module-level functions across 4 files

The feature commit changes the return type of stream_async / stream_sync from None to StreamResult. Callers that were ignoring the return value are unaffected.

Changelog

[2025-02-10]

Feedback received:

• (none yet)

Changes made:

• Initial implementation

[cursor]

PR Summary

Medium Risk
Changes public helper return types and centralizes streaming tool-call reconstruction used by the runner, which could affect downstream streaming consumers despite added unit coverage.

Overview
Streaming helpers now return structured results. stream_async/stream_sync still print tokens as they arrive, but now also accumulate full text plus reassembled tool-call deltas into a returned StreamResult.

Tool-call delta reassembly was extracted into shared accumulate_tool_call() and DedalusRunner was updated to use it, reducing duplicated streaming logic. Separately, _compat.model_dump() removes a duplicate by_alias argument that caused a Python 3.9 SyntaxError. Tests were heavily refactored for style and a new test_stream_helpers.py suite was added to cover the new stream behavior.

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