Open a page in the container's browser, at a viewport you choose

The pane could only ever watch a browser something else had published.
This opens one: a URL and a viewport, launched inside the container and
bound so the pane picks it up. Two uses, one action — a sign-in page,
where the callback listener is *in* the container and the loop closes
with no host round trip and no auth bridge, and a dev server on container
loopback, which is how you watch a UI Claude is building.

Reachable from both places the question comes up: "Open a page…" in the
Browser tab, and an "In container" button on the terminal's URL prompt.

Verified first, because it decided the design: a second client cannot
join a bound browser. `chromium.connect()` against the published endpoint
times out in every URL form (`ws+unix://…`, with and without the trailing
path) — that socket speaks the dashboard's own transport, not the public
connect protocol. Whoever launches is therefore the only process that can
drive, so the helper is resident and holds the handle, and live resize
applies to pages we opened and never to `@playwright/mcp`'s. Those take
`--viewport-size` / `PLAYWRIGHT_MCP_VIEWPORT_SIZE` at launch, which the
docs now say.

The viewport is the interesting half. Resizing the *window* does nothing
to the page — the viewer is a CDP screencast, so a bigger window is the
same pixels drawn larger, which is why pages have been looking like they
were rendered small. `page.setViewportSize()` genuinely reflows: measured
against a `@media (max-width: 900px)` rule, it fires at 800×600 and
clears at 1440×900. Match-window mode pushes the pop-out's settled size
into it, debounced by generation counter because a drag emits `Resized`
continuously and each one costs a container exec.

Control is a polled JSON file in /tmp: no port, no second listener,
nothing added to the proxy's surface, and URLs travel as argv to `node`
so no shell ever parses one. A re-open with a helper already up
navigates instead of relaunching — otherwise the second page would throw
away the session the first one just signed into.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src-tauri/src/browser_view/commands.rs

@@ -5,7 +5,7 @@
 use tauri::{AppHandle, State};
 
 use crate::browser_view::install::{self, BrowserSetupOutcome};
-use crate::browser_view::{manager, popout, BrowserViewState, BrowserViewStatus};
+use crate::browser_view::{manager, page, popout, BrowserViewState, BrowserViewStatus};
 use crate::AppState;
 
 /// Turn the pane on or off for a project.
@@ -164,6 +164,106 @@ pub async fn set_browser_view_popout_always_on_top(
     popout::set_always_on_top(&app_handle, &project_id, on_top)
 }
 
+/// Open a URL in a browser *inside* the container, published so the pane shows
+/// it.
+///
+/// Two uses, one action: an auth URL — where the OAuth callback listener is in
+/// the container too, so the loop closes without the host being involved at all
+/// — and a dev server on container loopback, which is how you watch a UI Claude
+/// is building.
+///
+/// The scheme allow-list mirrors the URL relay's: `http`/`https` only, so this
+/// can never be talked into opening `file:` on the container's filesystem.
+#[tauri::command]
+pub async fn open_page_in_container_browser(
+    project_id: String,
+    url: String,
+    width: u32,
+    height: u32,
+    state: State<'_, AppState>,
+) -> Result<page::PageState, String> {
+    let trimmed = url.trim();
+    if !(trimmed.starts_with("http://") || trimmed.starts_with("https://")) {
+        return Err("Only http:// and https:// URLs can be opened in the browser.".to_string());
+    }
+    let container_id = running_container(&state, &project_id, "opening a page").await?;
+    let detection = crate::browser_view::detect::detect(&container_id).await?;
+    page::open(
+        &container_id,
+        &detection,
+        trimmed,
+        page::Viewport::sane(width, height),
+    )
+    .await
+}
+
+/// Resize the page this opened. The pop-out's "match window" mode calls this on
+/// every settled resize, so it is deliberately cheap: one control-file write.
+#[tauri::command]
+pub async fn set_container_page_viewport(
+    project_id: String,
+    width: u32,
+    height: u32,
+    state: State<'_, AppState>,
+) -> Result<(), String> {
+    let container_id = running_container(&state, &project_id, "resizing the page").await?;
+    page::set_viewport(&container_id, page::Viewport::sane(width, height)).await
+}
+
+/// State of the page this opened, if any. Never fails: "no page" is an answer.
+#[tauri::command]
+pub async fn get_container_page_state(
+    project_id: String,
+    state: State<'_, AppState>,
+) -> Result<page::PageState, String> {
+    let Ok(container_id) = running_container(&state, &project_id, "reading the page").await else {
+        return Ok(page::PageState::default());
+    };
+    Ok(page::state(&container_id).await)
+}
+
+/// Close the page this opened, leaving the view itself running.
+#[tauri::command]
+pub async fn close_container_page(
+    project_id: String,
+    state: State<'_, AppState>,
+) -> Result<(), String> {
+    let container_id = running_container(&state, &project_id, "closing the page").await?;
+    page::close(&container_id).await;
+    Ok(())
+}
+
+/// Make the page track the pop-out window's size as it is dragged.
+///
+/// Only affects a page **this app opened**: a bound browser admits no second
+/// client, so one `@playwright/mcp` launched keeps the viewport it was given.
+/// Turning it on applies the window's current size immediately, so the toggle
+/// has a visible effect without waiting for a drag.
+#[tauri::command]
+pub async fn set_browser_view_match_window(
+    project_id: String,
+    enabled: bool,
+    app_handle: AppHandle,
+    state: State<'_, AppState>,
+) -> Result<(), String> {
+    popout::set_match_window(&project_id, enabled);
+    if !enabled {
+        return Ok(());
+    }
+    let Some((width, height)) = popout::inner_size(&app_handle, &project_id) else {
+        return Ok(());
+    };
+    let container_id = running_container(&state, &project_id, "matching the window").await?;
+    page::set_viewport(&container_id, page::Viewport::sane(width, height)).await
+}
+
+/// Whether match-window mode is on. Read on mount, like the rest of the
+/// pop-out's state — the pane is unmounted whenever another sub-tab is shown.
+#[tauri::command]
+pub async fn get_browser_view_match_window(project_id: String) -> Result<bool, String> {
+    Ok(popout::match_window(&project_id))
+}
+
 /// The project's container, or a sentence saying why there isn't one.
 ///
 /// Every command here needs a *running* container, and every one of them used