v3 M1b: runtime per-provider theming (firmware) + accent push (daemon)

The watch recolors to the active provider's brand, live, and it's cheap to add
more providers later.

Firmware:
- theme.h: expose THEME_ACCENT_HEX; ui.cpp: COL_ACCENT becomes a runtime
  lv_color_t backed by a shared style (s_accent_style). Static accent widgets
  (launcher tile icons, usage status line, session tokens) attach the shared
  style, so ui_set_theme() recolors them instantly via lv_obj_report_style_change
  — no widget tracking, no recreation.
- ui_set_theme(pv, accent_rgb): swaps the accent + a small logo table keyed by
  provider id (fallback to the Claude mark until a provider ships a logo). Change-
  guarded, so the ~3s payload cadence doesn't churn.
- main.cpp: parse "pv" (id) + "ac" (0xRRGGBB) from the payload and apply.
- Adding a provider needs zero firmware color edits (accent is data-driven) and
  at most one logo-table row.

Daemon: push "ac" = active provider's brand accent alongside "pv".

Test fix: test_providers used asyncio.run(), which closed the suite's shared
event loop and broke every later get_event_loop() test (Py3.13) — mirror the
repo's _run() helper instead.

Verified on the 2.06: forcing an OpenAI-green theme recolored the live launcher
icons (report_style_change path). 216 builds clean; daemon suite 94 passed.

firmware/src/ui.cpp

@@ -100,7 +100,13 @@ static void compute_layout(const BoardCaps& c) {
 #define COL_PANEL     THEME_PANEL
 #define COL_TEXT      THEME_TEXT
 #define COL_DIM       THEME_DIM
-#define COL_ACCENT    THEME_ACCENT
+// COL_ACCENT is runtime (v3): the daemon pushes each provider's brand accent and
+// ui_set_theme() swaps it live. Widgets that read COL_ACCENT directly pick up the
+// new value on their next update; static widgets attach s_accent_style so a
+// provider switch recolors them instantly (lv_obj_report_style_change).
+static lv_color_t g_accent = lv_color_hex(THEME_ACCENT_HEX);
+static lv_style_t s_accent_style;
+#define COL_ACCENT    g_accent
 #define COL_GREEN     THEME_GREEN
 #define COL_AMBER     THEME_AMBER
 #define COL_RED       THEME_RED
@@ -477,7 +483,7 @@ static void init_usage_screen(lv_obj_t* scr) {
     lbl_anim = lv_label_create(usage_container);
     lv_label_set_text(lbl_anim, "");
     lv_obj_set_style_text_font(lbl_anim, &font_mono_32, 0);
-    lv_obj_set_style_text_color(lbl_anim, COL_ACCENT, 0);
+    lv_obj_add_style(lbl_anim, &s_accent_style, 0);   // v3: recolors on provider switch
     lv_obj_align(lbl_anim, LV_ALIGN_BOTTOM_MID, 0, -15);
 }
 
@@ -516,7 +522,7 @@ static lv_obj_t* make_tile(lv_obj_t* parent, const AppEntry* app, int w, int h)
     lv_obj_t* icon = lv_label_create(tile);
     lv_label_set_text(icon, app->symbol);
     lv_obj_set_style_text_font(icon, &lv_font_montserrat_28, 0);
-    lv_obj_set_style_text_color(icon, COL_ACCENT, 0);
+    lv_obj_add_style(icon, &s_accent_style, 0);   // v3: recolors on provider switch
 
     lv_obj_t* lbl = lv_label_create(tile);
     lv_label_set_text(lbl, app->label);
@@ -712,7 +718,7 @@ static void init_session_screen(lv_obj_t* scr) {
     sess_tokens_lbl = lv_label_create(session_container);
     lv_label_set_text(sess_tokens_lbl, "\xE2\x80\x94 tokens");
     lv_obj_set_style_text_font(sess_tokens_lbl, &font_styrene_28, 0);
-    lv_obj_set_style_text_color(sess_tokens_lbl, COL_ACCENT, 0);
+    lv_obj_add_style(sess_tokens_lbl, &s_accent_style, 0);   // v3: recolors on provider switch
     lv_obj_align(sess_tokens_lbl, LV_ALIGN_TOP_MID, 0, L.content_y + 152);
 
     sess_gen_lbl = lv_label_create(session_container);
@@ -1282,6 +1288,11 @@ static void battery_screen_refresh(void) {
 void ui_init(void) {
     compute_layout(board_caps());
 
+    // Shared accent style (v3 theming) — MUST be initialized before any screen is
+    // built, so widgets can attach it. ui_set_theme() recolors it live.
+    lv_style_init(&s_accent_style);
+    lv_style_set_text_color(&s_accent_style, g_accent);
+
     lv_obj_t* scr = lv_screen_active();
     lv_obj_set_style_bg_color(scr, COL_BG, 0);
     lv_obj_set_style_bg_opa(scr, LV_OPA_COVER, 0);
@@ -1584,6 +1595,44 @@ screen_t ui_get_current_screen(void) {
     return current_screen;
 }
 
+// ---- v3 provider theming --------------------------------------------------
+// Per-provider logo on the usage screen. Only the Claude mark ships today; adding
+// a provider's logo is one row here plus an RGB565A8 asset. Unknown / not-yet-
+// added providers fall back to the Claude mark, so a switch still recolors.
+struct ProviderLogo { const char* pv; const lv_image_dsc_t* dsc; };
+static const ProviderLogo s_provider_logos[] = {
+    { "anthropic", &logo_dsc },
+    // { "openai", &logo_openai_dsc },   // add when the asset lands
+    // { "zai",    &logo_zai_dsc },
+};
+static const lv_image_dsc_t* logo_for(const char* pv) {
+    if (pv)
+        for (const auto& e : s_provider_logos)
+            if (strcmp(e.pv, pv) == 0) return e.dsc;
+    return &logo_dsc;   // fallback: Claude mark until the provider ships a logo
+}
+
+// Apply a provider's brand: recolor the shared accent style (every widget using
+// it repaints via report_style_change), retint the few non-text accent widgets,
+// and swap the logo. accent_rgb == 0 keeps the current accent (logo-only change).
+void ui_set_theme(const char* pv, uint32_t accent_rgb) {
+    // Change-guarded: the daemon stamps pv/ac on every write (~3s), so only act
+    // on an actual switch — otherwise report_style_change would churn constantly.
+    static uint32_t last_accent = THEME_ACCENT_HEX;
+    static char     last_pv[16] = "";
+    if (accent_rgb && accent_rgb != last_accent) {
+        last_accent = accent_rgb;
+        g_accent = lv_color_hex(accent_rgb);
+        lv_style_set_text_color(&s_accent_style, g_accent);
+        lv_obj_report_style_change(&s_accent_style);
+        if (dim_arc) lv_obj_set_style_arc_color(dim_arc, g_accent, LV_PART_INDICATOR);
+    }
+    if (pv && strncmp(pv, last_pv, sizeof(last_pv)) != 0) {
+        strlcpy(last_pv, pv, sizeof(last_pv));
+        if (logo_img) lv_image_set_src(logo_img, logo_for(pv));
+    }
+}
+
 void ui_update_ble_status(ble_state_t state, const char* name, const char* mac) {
     (void)name; (void)mac;
     bool was_connected = s_ble_connected;