diff --git a/codev/projects/bugfix-766-bug-architect-pane-shrinks-to-/status.yaml b/codev/projects/bugfix-766-bug-architect-pane-shrinks-to-/status.yaml
new file mode 100644
index 000000000..f6ceb4bff
--- /dev/null
+++ b/codev/projects/bugfix-766-bug-architect-pane-shrinks-to-/status.yaml
@@ -0,0 +1,12 @@
+id: bugfix-766
+title: bug-architect-pane-shrinks-to-
+protocol: bugfix
+phase: verified
+plan_phases: []
+current_plan_phase: null
+gates: {}
+iteration: 1
+build_complete: false
+history: []
+started_at: '2026-05-19T00:27:56.031Z'
+updated_at: '2026-05-19T00:59:00.634Z'
diff --git a/packages/codev/src/agent-farm/__tests__/e2e/architect-pane-layout.test.ts b/packages/codev/src/agent-farm/__tests__/e2e/architect-pane-layout.test.ts
new file mode 100644
index 000000000..6ed45ac19
--- /dev/null
+++ b/packages/codev/src/agent-farm/__tests__/e2e/architect-pane-layout.test.ts
@@ -0,0 +1,97 @@
+/**
+ * Bugfix #766: regression guard for the multi-architect (N>1) left pane layout.
+ *
+ * PR #762 introduced `.architect-pane` / `.architect-pane-body` wrappers in the
+ * N>1 branch of `App.tsx` but never added matching CSS, so the architect
+ * terminal collapsed to ~1/4 of the SplitPane left side. The fix in
+ * `packages/dashboard/src/index.css` makes `.architect-pane` a
+ * `position: absolute; inset: 0` flex column anchored against `.split-left`
+ * (which is `position: relative`), with `.architect-pane-body` as a `flex: 1`
+ * filler. This test pins the layout invariant by mocking `/api/state` with
+ * N=2 architects and asserting the architect-pane-body fills almost all of the
+ * SplitPane left side minus the tab strip.
+ *
+ * Prerequisites:
+ *   - Tower running on TOWER_TEST_PORT (default 4100)
+ *   - npx playwright install chromium
+ *
+ * Run: npx playwright test architect-pane-layout
+ */
+
+import { test, expect } from '@playwright/test';
+import { resolve } from 'node:path';
+
+const TOWER_URL = `http://localhost:${process.env.TOWER_TEST_PORT || '4100'}`;
+const WORKSPACE_PATH = resolve(import.meta.dirname, '../../../../../../');
+const ENCODED_PATH = Buffer.from(WORKSPACE_PATH).toString('base64url');
+const DASH_URL = `${TOWER_URL}/workspace/${ENCODED_PATH}/`;
+
+test.describe('Bugfix #766: multi-architect pane fills SplitPane left side', () => {
+  test('N=2 architect-pane-body fills the SplitPane left side', async ({ page }) => {
+    // Mock /api/state with two architects so the N>1 branch in App.tsx renders
+    // the `.architect-pane` / `.architect-pane-body` wrappers.
+    await page.route('**/api/state', async (route) => {
+      const response = await route.fetch();
+      const base = response.ok() ? await response.json().catch(() => ({})) : {};
+      const mainArchitect = { name: 'main', port: 0, pid: 1, terminalId: 'term-766-main', persistent: false };
+      const siblingArchitect = { name: 'sibling-766', port: 0, pid: 2, terminalId: 'term-766-sibling', persistent: false };
+      return route.fulfill({
+        status: 200,
+        contentType: 'application/json',
+        body: JSON.stringify({
+          ...base,
+          architect: mainArchitect,
+          architects: [mainArchitect, siblingArchitect],
+          builders: [],
+          utils: [],
+          annotations: [],
+        }),
+      });
+    });
+
+    await page.goto(DASH_URL);
+    await page.locator('#root').waitFor({ state: 'attached', timeout: 10_000 });
+
+    // Confirm the N>1 branch rendered: architect tab strip is visible.
+    const tabStrip = page.locator('[aria-label="Architect tabs"]');
+    await expect(tabStrip).toBeVisible({ timeout: 10_000 });
+
+    const splitLeft = page.locator('.split-left');
+    const architectPane = page.locator('.architect-pane');
+    const architectBody = page.locator('.architect-pane-body');
+
+    await expect(splitLeft).toBeVisible();
+    await expect(architectPane).toBeVisible();
+    await expect(architectBody).toBeAttached();
+
+    // The architect-pane wrapper should fill the full height of the SplitPane
+    // left side. Allow a small delta for borders / sub-pixel rounding.
+    const [leftBox, paneBox, stripBox, bodyBox] = await Promise.all([
+      splitLeft.boundingBox(),
+      architectPane.boundingBox(),
+      tabStrip.boundingBox(),
+      architectBody.boundingBox(),
+    ]);
+
+    expect(leftBox, '.split-left must have a bounding box').not.toBeNull();
+    expect(paneBox, '.architect-pane must have a bounding box').not.toBeNull();
+    expect(stripBox, 'architect tab strip must have a bounding box').not.toBeNull();
+    expect(bodyBox, '.architect-pane-body must have a bounding box').not.toBeNull();
+
+    // .architect-pane fills .split-left vertically (within 2px tolerance).
+    expect(Math.abs(paneBox!.height - leftBox!.height)).toBeLessThanOrEqual(2);
+
+    // .architect-pane-body fills the remaining space below the tab strip.
+    // Pre-fix, the body collapsed to ~0px (children-only intrinsic height
+    // since `Terminal` had no fixed height inside an undefined-height flex
+    // child). Post-fix it must be at least 60% of the left pane height.
+    const expectedMinBodyHeight = (leftBox!.height - stripBox!.height) * 0.6;
+    expect(bodyBox!.height).toBeGreaterThanOrEqual(expectedMinBodyHeight);
+
+    // And the body's bottom should reach (within 2px) the bottom of the
+    // split-left container — i.e. the pane is not collapsed to ~1/4 height.
+    const leftBottom = leftBox!.y + leftBox!.height;
+    const bodyBottom = bodyBox!.y + bodyBox!.height;
+    expect(Math.abs(leftBottom - bodyBottom)).toBeLessThanOrEqual(2);
+  });
+});
diff --git a/packages/dashboard/src/index.css b/packages/dashboard/src/index.css
index 4648fe13f..5ba2128d3 100644
--- a/packages/dashboard/src/index.css
+++ b/packages/dashboard/src/index.css
@@ -307,6 +307,25 @@ body {
   font-size: 14px;
 }
 
+/* Bugfix #766: multi-architect left-pane wrapper (Spec 761 N>1 path).
+ * Without these rules the wrappers collapse to intrinsic block height,
+ * leaving the architect terminal at ~1/4 of the SplitPane left side.
+ * `.split-left` already sets `position: relative`, so positioning the pane
+ * absolutely against it sidesteps any flex/percentage-height plumbing in
+ * ancestor containers. */
+.architect-pane {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  flex-direction: column;
+  min-height: 0;
+}
+
+.architect-pane-body {
+  flex: 1;
+  min-height: 0;
+}
+
 /* Virtual keyboard for mobile terminals (Issue #254) */
 .virtual-keyboard {
   display: flex;