diff --git a/.agent/knowledge/repo_discoveries.md b/.agent/knowledge/repo_discoveries.md
index e64c9c4d..1ce848cb 100644
--- a/.agent/knowledge/repo_discoveries.md
+++ b/.agent/knowledge/repo_discoveries.md
@@ -14,6 +14,14 @@ Use this log for durable findings that future contributors and agents should reu
 
 ## Discoveries
 
+- Date: 2026-03-20
+- Area: activities | syncdeck | embedded activity console
+- Discovery: SyncDeck’s instructor embedded-activity UX is split between an ad hoc `Activities` launcher and a separate `Running activities` manager, but both surfaces already depend on the same local embedded-activity state (`embeddedActivities`, `activeEmbeddedInstanceKey`, and instance-key anchor helpers). A unified activities panel can stay client-side by reusing the existing launch flow for new instances and the existing resync/navigation helpers for switching to running instances.
+- Why it matters: This is a UI/state composition problem more than a data-contract problem. Future embedded-activity console changes should prefer reusing instance-key navigation helpers instead of introducing new server state just to support switching among running embedded sessions.
+- Evidence: `activities/syncdeck/client/manager/SyncDeckManager.tsx`; `activities/syncdeck/client/manager/SyncDeckManager.test.tsx`; `activities/syncdeck/COMBINED_ACTIVITIES_CONTROL_PLAN.md`
+- Follow-up action: If the unified panel is implemented, keep launch actions and running-instance actions distinct in the UI so switching never accidentally creates a second child session on the same anchor.
+- Owner: Codex
+
 - Date: 2026-03-19
 - Area: server | activities | persistent-bootstrap
 - Discovery: Persistent-session startup now copies canonical permalink `selectedOptions` into the started live session's `data.embeddedLaunch.selectedOptions`, and Algorithm Demo manager bootstrap reads its initial algorithm from that embedded-launch state instead of the manage-route query string.
diff --git a/activities/syncdeck/COMBINED_ACTIVITIES_CONTROL_PLAN.md b/activities/syncdeck/COMBINED_ACTIVITIES_CONTROL_PLAN.md
new file mode 100644
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@@ -0,0 +1,178 @@
+# SyncDeck Combined Activities Control Plan
+
+## Goal
+
+Replace the separate `Activities` launcher button and `Running activities: N` management chip in the SyncDeck instructor console with a single control that supports both:
+
+- launching ad hoc embedded activities on the current slide anchor
+- switching among all currently running embedded activities
+
+The combined control should behave like the primary embedded-activity entry point for the instructor.
+
+## Current State
+
+Today the instructor console exposes two adjacent controls in
+[`activities/syncdeck/client/manager/SyncDeckManager.tsx`](/workspaces/ActiveBits/activities/syncdeck/client/manager/SyncDeckManager.tsx):
+
+- `Activities`
+  - opens `syncdeck-activity-picker-panel`
+  - lists launchable activities only
+  - does not show running instances
+- `Running activities: N`
+  - opens `syncdeck-running-activities-panel`
+  - lists already running embedded activity instances
+  - supports end/report actions
+  - does not support launching a new activity
+
+This split makes the instructor switch mental models depending on whether they want to start or manage an activity, even though both actions are part of the same embedded-activity workflow.
+
+## Target UX
+
+Use a single `Activities` button as the only embedded-activity console entry point.
+
+The button should:
+
+- remain visible in the instructor toolbar
+- show useful running-state context, for example `Activities (2)` when there are running instances
+- open one unified panel instead of two separate panels
+
+The unified panel should contain two sections:
+
+1. `Running Activities`
+   - appears first when one or more embedded activities exist
+   - lets the instructor switch to any running activity
+   - preserves existing end/report controls
+   - clearly marks the currently active embedded instance
+
+2. `Launch Activity`
+   - lists launchable activity types
+   - preserves the current ad hoc launch behavior
+   - continues to launch on the current slide anchor using the existing start flow
+
+## Interaction Model
+
+### Button behavior
+
+- Clicking `Activities` toggles a single panel.
+- The old `Running activities: N` button should be removed.
+- The button label should incorporate running count when non-zero.
+
+### Running activity switching
+
+Selecting a running activity should:
+
+- navigate the instructor view to that activity's anchor if needed
+- surface that activity as the active embedded manager overlay
+- avoid launching a duplicate embedded child if the chosen instance already exists
+
+Expected implementation direction:
+
+- reuse the existing instance-key based positioning helpers
+- use `buildManagerResyncCommandForInstanceKey(instanceKey)` when the requested activity is not currently active
+- close the unified panel after switching
+
+### Launch behavior
+
+Launching from the unified panel should:
+
+- keep the existing `handleActivityPickerLaunch` / `handleResolvedActivityRequests` flow
+- close the unified panel after a successful launch request is initiated
+- remain disabled when the configure panel is open
+
+### Empty state behavior
+
+When no embedded activities are running:
+
+- the unified panel should still open normally
+- the running section should show a simple empty state
+- the launch section should still be immediately available
+
+## Proposed Implementation Steps
+
+- [ ] Introduce a single panel state for the combined activities control in `SyncDeckManager`.
+- [ ] Remove the standalone running-activities button and panel.
+- [ ] Move the running-activity list UI into the combined activities panel.
+- [ ] Add a switch action for each running instance.
+- [ ] Preserve existing end-confirmation and report-download affordances for running instances.
+- [ ] Update the button label so it communicates current running count.
+- [ ] Ensure launch and switch actions close or preserve panel state intentionally.
+- [ ] Add or update tests for unified button rendering, empty/running panel states, and switch behavior helpers.
+- [ ] Update durable notes if implementation reveals reusable SyncDeck embedded-activity navigation guidance.
+
+## Data and State Notes
+
+No server contract change is expected for the first pass.
+
+This should remain a manager-only UI/state refactor built on the existing client-side data:
+
+- `embeddedActivities`
+- `runningEmbeddedActivityCount`
+- `activeEmbeddedInstanceKey`
+- `resolveManagerActiveEmbeddedInstanceKey(...)`
+- `buildManagerResyncCommandForInstanceKey(...)`
+- existing embedded end/report handlers
+
+## Risks and Design Questions
+
+### 1. Switch semantics versus launch semantics
+
+Launching creates a new child session. Switching should not.
+
+Guardrail:
+
+- keep launch actions wired only to activity-type entries
+- keep switch actions wired only to existing instance keys
+
+### 2. Multiple running instances of the same activity type
+
+The panel must distinguish instances by more than `activityId`.
+
+Recommendation:
+
+- show activity name plus instance key or anchor context
+- keep child session id available as secondary metadata when useful
+
+### 3. Active-instance discoverability
+
+The instructor should understand which embedded activity is currently shown.
+
+Recommendation:
+
+- preserve the current `Active` indicator in the running section
+- add a `Switch` or `Open` button for non-active rows
+- consider replacing the action with `Viewing` for the active row
+
+### 4. Panel density
+
+Combining both sections into one panel may increase height.
+
+Recommendation:
+
+- keep the panel scrollable
+- prioritize the running section first so active management is not hidden below the launch list
+
+## Verification Plan
+
+Minimum checks after implementation:
+
+- `npm_config_target=activities/syncdeck npm --workspace activities run test:scope`
+- `npm_config_target=activities/syncdeck npm --workspace activities run lint:scope`
+- `npm --workspace activities run typecheck`
+
+Suggested test coverage:
+
+- manager renders one combined `Activities` control instead of separate controls
+- combined panel shows running-count context when instances exist
+- combined panel renders empty running state when none exist
+- helper logic for switching to a running instance resolves the correct navigation command
+- launch list remains available inside the combined panel
+
+## Success Criteria
+
+The work is complete when:
+
+- instructors use one `Activities` entry point for both launch and running-instance management
+- running activities are switchable without opening a separate panel
+- existing end/report capabilities remain intact
+- ad hoc launch still works from the same surface
+- SyncDeck manager tests, lint, and typecheck pass