fix: keep conversation composer in the viewport under layout push

Long unbreakable tokens (OAuth URLs) grew the AppFrame center column past the viewport because the layout-push rule used the grid default min-height:auto. Cap --dsh-sidebar-height the same way setBottomHeight does (viewport minus PANEL_MIN) and let the column shrink and wrap.

tests/layout-css.spec.ts

@@ -0,0 +1,22 @@
+/**
+ * layout.css must let the DSH conversation column shrink below its content
+ * size. Without min-height:0 a long unbreakable URL grows the grid item
+ * past the viewport and clips the composer.
+ */
+import { readFileSync } from 'node:fs'
+import { describe, expect, it } from 'vitest'
+
+const css = readFileSync('src/client/layout.css', 'utf8')
+
+describe('layout.css conversation column', () => {
+  it('targets the AppFrame center column', () => {
+    expect(css).toContain('[data-pane="conversation"]')
+    expect(css).toContain('[data-slot="conversation"]')
+  })
+
+  it('allows the center column to shrink and wrap long tokens', () => {
+    expect(css).toMatch(/min-height:\s*0/)
+    expect(css).toMatch(/overflow:\s*hidden/)
+    expect(css).toMatch(/overflow-wrap:\s*anywhere/)
+  })
+})

tests/layout-push.spec.ts

@@ -0,0 +1,75 @@
+/**
+ * Layout-push size contract: the conversation column (output + composer)
+ * must keep at least PANEL_MIN of the viewport after the bottom panel
+ * claims its height. A stale persisted bottomHeight (or a cap at 100vh)
+ * used to crush the composer off-screen.
+ */
+import { describe, expect, it } from 'vitest'
+import { BOTTOM_MIN, PANEL_MIN } from '../src/client/state.ts'
+import { layoutPushSize } from '../src/client/layout-push.ts'
+
+describe('layoutPushSize', () => {
+  it('pushes nothing on a narrow drawer viewport', () => {
+    expect(layoutPushSize({
+      narrow: true,
+      panelOpen: true,
+      bottomOpen: true,
+      width: 400,
+      bottomHeight: 400,
+      viewportWidth: 390,
+      viewportHeight: 700,
+    })).toEqual({ width: 0, height: 0 })
+  })
+
+  it('pushes nothing when both panels are collapsed', () => {
+    expect(layoutPushSize({
+      narrow: false,
+      panelOpen: false,
+      bottomOpen: false,
+      width: 400,
+      bottomHeight: 400,
+      viewportWidth: 1280,
+      viewportHeight: 800,
+    })).toEqual({ width: 0, height: 0 })
+  })
+
+  it('caps an oversize bottom panel so the conversation keeps PANEL_MIN', () => {
+    const viewportHeight = 800
+    const size = layoutPushSize({
+      narrow: false,
+      panelOpen: false,
+      bottomOpen: true,
+      width: 0,
+      bottomHeight: 10_000,
+      viewportWidth: 1280,
+      viewportHeight,
+    })
+    expect(size.height).toBe(viewportHeight - PANEL_MIN)
+    expect(size.height).toBeGreaterThanOrEqual(BOTTOM_MIN)
+    expect(viewportHeight - size.height).toBeGreaterThanOrEqual(PANEL_MIN)
+  })
+
+  it('caps an oversize right panel at the viewport width', () => {
+    expect(layoutPushSize({
+      narrow: false,
+      panelOpen: true,
+      bottomOpen: false,
+      width: 10_000,
+      bottomHeight: 0,
+      viewportWidth: 1280,
+      viewportHeight: 800,
+    })).toEqual({ width: 1280, height: 0 })
+  })
+
+  it('passes through in-range open sizes', () => {
+    expect(layoutPushSize({
+      narrow: false,
+      panelOpen: true,
+      bottomOpen: true,
+      width: 400,
+      bottomHeight: 220,
+      viewportWidth: 1280,
+      viewportHeight: 800,
+    })).toEqual({ width: 400, height: 220 })
+  })
+})