diff --git a/dashboard/handlers/projects.py b/dashboard/handlers/projects.py
index 17d815f..2ebc773 100644
--- a/dashboard/handlers/projects.py
+++ b/dashboard/handlers/projects.py
@@ -690,6 +690,35 @@ class ProjectsHandlers:
         """Dashboard planning sessions live in adapter='dashboard', channel=slug."""
         return ("dashboard", slug)
 
+    @staticmethod
+    def _resolve_planning_key(slug: str) -> tuple[str, str]:
+        """Find the active session's (adapter, channel) for slug, regardless of
+        where it was started. Falls back to ('dashboard', slug) if nothing
+        matches — preserving prior behavior for the no-session case.
+
+        Picks the most-recently-updated entry when multiple exist.
+        """
+        try:
+            from src.planning_session import _load_planning_state  # type: ignore
+        except Exception:
+            return ("dashboard", slug)
+        try:
+            all_state = _load_planning_state()
+        except Exception:
+            return ("dashboard", slug)
+
+        matches = [
+            entry for entry in all_state.values()
+            if (entry.get("slug") or "").lower() == slug.lower()
+        ]
+        if not matches:
+            return ("dashboard", slug)
+        matches.sort(key=lambda e: e.get("updated_at") or "", reverse=True)
+        best = matches[0]
+        adapter = best.get("adapter") or "dashboard"
+        channel = best.get("channel_id") or slug
+        return (adapter, channel)
+
     # ── POST /api/projects/<slug>/plan/start ──────────────────────
     def handle_plan_start(self, slug: str):
         if validate_slug(slug):
@@ -793,7 +822,7 @@ class ProjectsHandlers:
             self.send_json({"error": "message required"}, 400)
             return
 
-        adapter, channel = self._planning_key(slug)
+        adapter, channel = self._resolve_planning_key(slug)
         try:
             from src.planning_orchestrator import PlanningOrchestrator  # type: ignore
             session, text, phase_ready = PlanningOrchestrator.respond(
@@ -915,7 +944,7 @@ class ProjectsHandlers:
         if validate_slug(slug):
             self.send_json({"error": "invalid_slug"}, 400)
             return
-        adapter, channel = self._planning_key(slug)
+        adapter, channel = self._resolve_planning_key(slug)
         try:
             from src.planning_session import get_planning_state, clear_planning_state  # type: ignore
             from src.planning_orchestrator import PlanningOrchestrator  # type: ignore
@@ -964,7 +993,7 @@ class ProjectsHandlers:
         if validate_slug(slug):
             self.send_json({"error": "invalid_slug"}, 400)
             return
-        adapter, channel = self._planning_key(slug)
+        adapter, channel = self._resolve_planning_key(slug)
         try:
             from src.planning_orchestrator import PlanningOrchestrator  # type: ignore
         except Exception as exc:
@@ -992,7 +1021,7 @@ class ProjectsHandlers:
         if validate_slug(slug):
             self.send_json({"error": "invalid_slug"}, 400)
             return
-        adapter, channel = self._planning_key(slug)
+        adapter, channel = self._resolve_planning_key(slug)
         try:
             from src.planning_orchestrator import PlanningOrchestrator  # type: ignore
             session, text, completed = PlanningOrchestrator.advance(adapter, channel)