Side pane

The agent console is worth more when the tooling around the work opens beside it. The side pane is the cheapest tier of that: any page of the Esposter app, opened in the console with no code written for it, so the resource explorer beside the session that is editing a resource needs nothing more than the link the agent already writes.

How it works

sequenceDiagram
    participant Reader
    participant Markdown as Conversation link
    participant Pane as Side pane store
    participant Frame as Same-origin frame
    participant App as App layouts

    Reader->>Markdown: clicks a link to a page of the app
    Markdown->>Pane: openPage — the path, not a new tab
    Pane->>Frame: src is the path with the embed flag added
    Frame->>App: the page loads with ?embed in its query
    App->>App: useIsEmbedded — no dock, no drawers, no resource trail
    App-->>Frame: the page itself, drawn unchanged

• The embed flag. A page framed by the pane carries ?embed in its query (EMBED_QUERY_KEY, built by getEmbeddedPath). The app's root reads it once, through useIsEmbedded, and drops the dock; the default layout drops its drawers and the resource layout drops its trail and service menu. The page's own content is not touched, so every page of the app is embeddable with no change to it.
• Frames, not proxies. Each open page is a same-origin iframe, so the auth cookie, the page's own state and its tRPC calls behave exactly as they do in a tab of their own. Every frame stays mounted while its tab is in the background, so a page keeps its place when it is shown again.
• Links open in the pane. A link in a message of the conversation, or in the composer's stream, opens in the pane when it points at this app's origin. A modifier key (Ctrl, Cmd or Shift) keeps the link's own behaviour and opens a tab, and a link to an anchor on the console's own page scrolls there.
• Layout. The pane stands beside the console's tabs, behind a handle on its start edge that the reader drags to resize it, remembered by the browser as LocalStorageKey.AgentConsolePaneWidth. It never grows so wide the tabs keep less than the pane's own least width, whatever width was remembered on a wider window. It appears only while a page is open there, and closing its last tab closes it.

Decisions

• Only the conversation's links open in the pane. A link in a tool result or a shell's output is left to the browser, since those surfaces render text the agent did not write as a link to the app.
• The open pages are not kept through a reload. The pane's tabs live in the page's memory, as its frames do, and a reload starts with none open; the width is the only thing remembered.
• No fallback tab for a page that refuses a frame. No page of the app sets frame headers, so a page that cannot be framed is not a case yet. Its fallback, a new tab with the pane's tab saying so, waits until a page sets one.
• Navigation inside a frame keeps the frame. A page that links elsewhere in the app navigates inside the frame, and the embed flag is kept only where the page's own link carries it.

Key files