Why: D44/D45 approved — card content streaming lets users watch long
artifacts materialize in the inbox instead of a single submit_card blob.
Evidence: cardsvc Append with 250ms emit throttle (persist-every-append);
runmgr Begin/Append/CommitStreamCard + finishRun fallback marking
uncommitted stream cards done/failed with warn tone; llm.go declares the
three tools under ui.cardflow with hallucination rejection; mock
#cardstream demo; new unit tests (TestLLMRunnerCardStreamTools/Gated,
TestAppendStreamThrottleAndMerge) and e2e TestMockCardflowStreamLoop.
Impact: no change to existing submit_card path or wire protocol;
card.updated payload already carried full cards (projection semantics).
Refs: documents proposal 2026-09-30-card-stream-artifact-unify-project-inbox.md (D44/D45).
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