[loganj]

🤖

Summary

• Stacked on feat(agents): session state and the retype preview over the agents port #1734. In layer 3 the agents service runs in a hidden agents web view and the screens stay in main. A MessagePort cannot connect two web views, so this adds a port that carries the agents protocol over Tauri events.
• Nothing uses it yet, so behavior does not change. The agents window PR will connect the two pages with it and add the event permissions.

Details

• eventPort(from, to) returns the port shape the protocol already uses (onmessage, postMessage, close). AgentsPort in port.ts names that shape, and MessagePort still fits it.
• Order: separate emits are separate IPC requests and can arrive out of order. The protocol needs a call's answer to arrive after the state push before it. So each frame has a sequence number, and the receiver holds a frame until the frames before it have arrived.
• Startup and reload: each page load is a session. A page announces its session once it listens, and answers a new peer's announcement with its own. Until it knows the peer, it holds what it sends. Frames name the session they are for. When a page reloads, the other page starts again with the new session and drops late frames from the old one. What was sent to a page that reloaded is lost with it.
• Frames also name the sending web view, so a third web view cannot pose as the peer.
• connectAgents now sends hello on connect, and the service answers it with a full push. A screens' page that reloads gets the current state without waiting for a change.
• Messages are JSON on this path. The protocol already sends plain data.

Testing

• event-port.test.ts, over a fake event bus that delivers each batch in reverse and as JSON:
  • Frames that arrive out of order are delivered in the order sent.
  • What a page sends before the other page is up waits for it.
  • A reloaded page is served afresh, and the old page's late frame is dropped.
  • Frames for another web view are ignored.
• port.test.ts: the real service and client over two event ports, with the screens' page loading first. Then the screens' page reloads and still gets the state.
• Mutation checks: each of these makes its test fail: removing the hold that restores order, removing the drop of a reloaded page's frames, and removing hello.
• tsc --noEmit, Biome, and vitest run src/features/agents (726 passed) pass.

🤖 Generated with Claude Code

[loganj]

🤖 Closing this PR because the column stack contains its work. event-port.ts is in #1893 (#1893), and link.ts from #1833 (#1833) replaces port.ts.