test(desktop): story-cover agent graph failure and edge states

[liuxiaocs7]

test(desktop): story-cover agent graph failure and edge states

Seventh surface under #3944 (one surface per PR): the Agent Graph panel had no
Storybook story. Add its failure and edge states, mounted through a scoped
window.maka.graphs bridge inside the real composer host seam
(.maka-detail-with-artifacts → .mainColumn), each pinning one
AgentGraphClientSnapshot.

• EmptyGraph — graph mode enabled, no operators yet: the panel's empty state.
• FailedGraph — a failed operator beside completed/running ones.
• BlockedOnUpstream — a blocked operator with the amber "waiting for input" line.
• ManyOperators — a wide fan-out (28 operators) with no fabricated omitted count
  (the read-model only elides operators past 256) — review feedback.
• LoadError — the IPC snapshot read rejects: the panel's error Banner + Retry.

The panel renders operators as a flat list (no edges/hierarchy), so tree depth
and cycles have no distinct rendering and are left out. Plays assert
reachability of each state; exact row counts / omitted lines are read-model
contracts left to the read-model's own tests (review feedback).

Refs #3944, #3893

Generative tooling

Claude Code contributed substantially here — it authored these Storybook stories. The human contributor of record reviewed and submitted the change, and each commit carries a Generated-by: Claude Code trailer per CONTRIBUTING.md.

Visual evidence

Storybook stories captured with Playwright (hosted on the fork's release assets).

empty-graph — normal / light · narrow / dark

failed-graph — normal / light · narrow / dark

blocked-on-upstream — normal / light · narrow / dark

many-operators — normal / light · narrow / dark

load-error — normal / light · narrow / dark

[Astro-Han]

Thanks for adding the missing Agent Graph review surface through the production AgentGraphPanel and its existing window.maka.graphs boundary. The empty, failed, blocked, many-operator, and load-error states are protocol-valid and visibly distinct; omitting tree depth/cycles is also the simpler and correct choice because this panel renders a flat operator list. I found no P0/P1 issues, and the exact-head test check is green. Approved.

中文对照

谢谢你通过真实的 AgentGraphPanel 和既有 window.maka.graphs 边界补上 Agent Graph 的审查面。空状态、失败、受阻、大量 operator 和加载失败都符合协议且视觉上彼此不同；由于当前面板只是扁平列表，不伪造树深度和环也是更简单、正确的选择。我没有发现 P0/P1，当前 exact head 的 test 已通过，因此批准。

AI-assisted review: Codex traced the fixture bridge and production component path; I verified the problem, reachability, exact head, and conclusion.