feat(metrics): compiles and runs remember which gallery example they came from

useProjectStore.currentExampleId — stamped by loadExample, dropped the
moment a real project (or a blank workspace) takes over. The compile
request and the run event carry it as example_id, analytics only, so
'which examples get compiled and run most' becomes answerable.

backend/app/api/routes/compile.py

@@ -168,6 +168,9 @@ class CompileRequest(BaseModel):
     # RP2350 boards all compile as rpipico2), and only the kind can tell
     # them apart. Rides into the metric hook's `extra`.
     board_kind: str | None = None
+    # Optional: gallery example the workspace was loaded from. Analytics
+    # only ("which examples get compiled most"); rides in `extra` too.
+    example_id: str | None = None
     # Per-board ESP32 build options (Partition Scheme, CPU Freq, Flash Mode,
     # PSRAM, etc.). Loose dict so the frontend can add fields without a
     # backend deploy — espidf_compiler.compile validates known keys and
@@ -520,6 +523,7 @@ async def _compile_job(
                 "async": True,
                 "initiated_by": request.initiated_by,
                 "board_kind": request.board_kind,
+                "example_id": request.example_id,
                 "partition_scheme": (request.board_options or {}).get("partitionScheme"),
                 "spiffs_file_count": len(request.spiffs_files or []),
             },
@@ -541,7 +545,7 @@ async def _compile_job(
             success=False,
             duration_ms=int((time.monotonic() - started) * 1000),
             error_kind="exception",
-            extra={"file_count": len(files), "exception": str(exc)[:200], "async": True, "initiated_by": request.initiated_by, "board_kind": request.board_kind},
+            extra={"file_count": len(files), "exception": str(exc)[:200], "async": True, "initiated_by": request.initiated_by, "board_kind": request.board_kind, "example_id": request.example_id},
         )
 
 
@@ -574,7 +578,7 @@ async def compile_sketch(
             success=False,
             duration_ms=int((time.monotonic() - started) * 1000),
             error_kind="exception",
-            extra={"file_count": len(files), "exception": str(e)[:200], "initiated_by": request.initiated_by, "board_kind": request.board_kind},
+            extra={"file_count": len(files), "exception": str(e)[:200], "initiated_by": request.initiated_by, "board_kind": request.board_kind, "example_id": request.example_id},
             request=http_request,
         )
         raise HTTPException(status_code=500, detail=str(e))
@@ -592,6 +596,7 @@ async def compile_sketch(
             "has_wifi": response.has_wifi,
             "initiated_by": request.initiated_by,
                 "board_kind": request.board_kind,
+                "example_id": request.example_id,
             "partition_scheme": (request.board_options or {}).get("partitionScheme"),
             "spiffs_file_count": len(request.spiffs_files or []),
         },

frontend/src/components/editor/EditorToolbar.tsx

@@ -235,6 +235,7 @@ export const EditorToolbar = ({
         project_id: currentProject?.id ?? null,
         board_fqbn: fqbn ?? null,
         board_kind: boardKind ?? null,
+        example_id: useProjectStore.getState().currentExampleId,
         engine: engine ?? null,
       });
     },
@@ -573,6 +574,7 @@ export const EditorToolbar = ({
           boardOptions: activeBoard?.boardOptions,
           spiffsFiles: activeBoard?.spiffsFiles,
           boardKind: kind ?? undefined,
+          exampleId: useProjectStore.getState().currentExampleId,
           // P2.4 — THIS board's declared manifest (compile scope). Per-board so
           // two boards can use different libraries without clashing.
           libraries: activeBoard?.libraries?.length ? activeBoard.libraries : null,
@@ -1079,7 +1081,7 @@ export const EditorToolbar = ({
               })),
             ]);
           },
-          { boardOptions: board.boardOptions, spiffsFiles: board.spiffsFiles, boardKind: board.boardKind, libraries: board.libraries?.length ? board.libraries : null, language: board.languageMode === 'espidf' ? 'espidf' : undefined },
+          { boardOptions: board.boardOptions, spiffsFiles: board.spiffsFiles, boardKind: board.boardKind, exampleId: useProjectStore.getState().currentExampleId, libraries: board.libraries?.length ? board.libraries : null, language: board.languageMode === 'espidf' ? 'espidf' : undefined },
         );
 
         const resultLogs = parseCompileResult(result, label, boardTarget, lastStreamedLen > 0);

frontend/src/services/compilation.ts

@@ -31,6 +31,9 @@ export interface CompileExtras {
   // FQBN (Pimoroni RP2350 boards all compile as rpipico2); the kind is the
   // only identifier that tells them apart in the metrics.
   boardKind?: string;
+  // Gallery example the workspace was loaded from — analytics only
+  // ("which examples get compiled most"). Null/omitted outside examples.
+  exampleId?: string | null;
 }
 
 export interface CompileResult {
@@ -127,6 +130,7 @@ export async function compileCode(
         board_options,
         spiffs_files,
         board_kind: extras?.boardKind ?? null,
+        example_id: extras?.exampleId ?? null,
         libraries,
         language: extras?.language ?? null,
         initiated_by: extras?.initiatedBy ?? null,

frontend/src/services/metricsService.ts

@@ -14,6 +14,8 @@ export interface RunEventPayload {
   board_fqbn?: string | null;
   /** Editor BoardKind — disambiguates boards that share an FQBN (analytics). */
   board_kind?: string | null;
+  /** Gallery example the workspace was loaded from (analytics). */
+  example_id?: string | null;
   /** Which engine took this run — 'instant' (browser) or 'linux' (guest).
    *  Absent for boards where the question doesn't apply. */
   engine?: 'instant' | 'linux' | null;

frontend/src/store/useProjectStore.ts

@@ -13,8 +13,16 @@ interface CurrentProject {
 
 interface ProjectState {
   currentProject: CurrentProject | null;
+  /**
+   * Gallery example currently loaded in the editor (null when the workspace
+   * came from a project, a file or scratch). Set by loadExample, cleared
+   * whenever a project takes over — analytics only: compiles/runs stamp it
+   * so "which examples get compiled most" is answerable.
+   */
+  currentExampleId: string | null;
   setCurrentProject: (project: CurrentProject) => void;
   clearCurrentProject: () => void;
+  setCurrentExampleId: (id: string | null) => void;
   // Updated to accept either the legacy boolean OR the new enum so the
   // ShareModal callsite and any older callers keep working uniformly.
   setVisibility: (next: boolean | ProjectVisibility) => void;
@@ -22,8 +30,14 @@ interface ProjectState {
 
 export const useProjectStore = create<ProjectState>((set) => ({
   currentProject: null,
-  setCurrentProject: (project) => set({ currentProject: project }),
-  clearCurrentProject: () => set({ currentProject: null }),
+  currentExampleId: null,
+  // Loading a real project supersedes the example context.
+  setCurrentProject: (project) => set({ currentProject: project, currentExampleId: null }),
+  // Also drops the example context: every caller (new project, blank
+  // workspace, logout cleanup) means "this workspace is no longer that".
+  // loadExample re-stamps its id right after calling this.
+  clearCurrentProject: () => set({ currentProject: null, currentExampleId: null }),
+  setCurrentExampleId: (id) => set({ currentExampleId: id }),
   setVisibility: (next) =>
     set((s) => {
       if (!s.currentProject) return s;

frontend/src/utils/loadExample.ts

@@ -114,6 +114,8 @@ export async function loadExample(
   // sees null as projectId during every subsequent simulator/editor change,
   // so no PUT goes out.
   useProjectStore.getState().clearCurrentProject();
+  // Analytics context: compiles/runs from this workspace stamp the example id.
+  useProjectStore.getState().setCurrentExampleId(example.id);
 
   // P2.4 — this example's declared manifest (compile scope) is assigned to each
   // board it creates at the END of this function (the boards don't exist yet).