feat(runtime3): condition action + dict actions

Extend the Runtime 3 IR spec with a standalone 'condition' action
kind that takes {expr, then[], else[]} sublists, keeping branching
local to the current step (no extra transitions or step duplication).

The validator now accepts both string-form (legacy firmware import)
and dict-form actions, recursively validating condition.then /
condition.else as nested action lists. STANDARD_ACTION_KINDS gains
the full set of blocks_studio kinds (audio, LCD, hardware, ESP-NOW,
BOX-3, M5, PLIP) so the blocks-to-IR codec output passes validation
end-to-end.

specs/ZACUS_RUNTIME_3_SPEC.md

@@ -54,3 +54,45 @@ Define a portable runtime artifact that can be compiled from YAML or Blockly-aut
 - Entry step is resolved from `scenario.entry_step_id`.
 - A simulator can replay deterministic transition events without hardware.
 - Firmware adapters may enrich steps with board-specific actions, but not mutate story flow semantics.
+
+## Action Shape
+
+Actions are emitted by authoring tools (blocks studio, firmware import, hand-written YAML) and consumed by runtime adapters. Two equivalent shapes are accepted:
+
+- **String form** (legacy firmware import): `"led_pattern:rainbow"` — opaque, runtime parses at its discretion.
+- **Dict form** (preferred for new authoring): `{ "kind": "<name>", ...payload }`.
+
+### Standard action kinds
+
+| `kind` | Payload | Semantics |
+|--------|---------|-----------|
+| `tts_say` | `text: string` | Speak `text` via the active TTS backend |
+| `wait_user_voice` | `timeout_ms: int` | Block until utterance end or timeout |
+| `hw_servo` | `channel: int, angle: int` | Set servo on `channel` to `angle` degrees |
+| `qr_expect` | `value: string` | Arm the QR matcher with expected payload |
+| `led_pattern` | `pattern: string` | Play a named LED pattern |
+| `sound_play` | `asset: string` | Play an asset from the media manager |
+| `score_add` | `delta: int` | Mutate the run-scoped score variable |
+| `set_var` | `name: string, value: string` | Set a scenario variable |
+| `condition` | `expr: string, then: [action,…], else: [action,…]` | **Standalone branching.** Evaluate `expr`; execute the `then` action list if truthy, `else` otherwise. Nested `condition` actions are allowed. |
+
+### `condition` action
+
+The `condition` action keeps **branching local to the current step** — no extra transitions or step duplication needed for simple if/else logic. The runtime evaluates `expr` against the current variable scope (left intentionally loose; runtimes that don't implement evaluation MAY treat unknown `expr` as falsy and log it).
+
+Authoring tools that produce `condition` actions (e.g. `BlockKind.logicIf` in the Blocks Studio) MUST place all branch-local actions inside `then` / `else`. Use a transition (event_type `action`, event_name `goto:<target>`) when you need to jump to another step, not a `condition`.
+
+Example:
+```json
+{
+  "kind": "condition",
+  "expr": "score >= 3",
+  "then": [
+    { "kind": "tts_say", "text": "Bravo, niveau suivant." },
+    { "kind": "set_var", "name": "unlocked_act2", "value": "true" }
+  ],
+  "else": [
+    { "kind": "tts_say", "text": "Encore un effort." }
+  ]
+}
+```

tools/scenario/runtime3_common.py

@@ -218,6 +218,46 @@ def compile_runtime3_document(data: dict[str, Any], source_kind: str = "yaml") -
     }
 
 
+STANDARD_ACTION_KINDS = {
+    "tts_say", "wait_user_voice",
+    "hw_servo", "qr_expect", "led_pattern",
+    "sound_play", "sound_stop", "sound_volume",
+    "lcd_text", "lcd_clear", "lcd_image", "lcd_touch_wait",
+    "buzzer_tone", "relay", "sensor_read", "button_wait",
+    "espnow_register_peer", "espnow_send", "espnow_broadcast", "espnow_wait",
+    "box_imu_shake", "box_ir_send",
+    "m5_beep", "m5_lcd_text", "m5_button_wait", "m5_rgb_led", "m5_imu_shake",
+    "plip_ring", "plip_pickup_wait",
+    "score_add", "set_var",
+    "if_condition",  # deprecated alias, kept for older blocks codec output
+    "condition",
+}
+
+
+def validate_action(action: Any, *, step_id: str, path: str = "actions") -> None:
+    """Accept string-form (legacy firmware) or dict-form actions.
+
+    Dict-form actions must carry a non-empty `kind`. `condition` actions are
+    recursively validated to ensure their `then` / `else` lists hold actions.
+    """
+    if isinstance(action, str):
+        return
+    if not isinstance(action, dict):
+        raise ValueError(f"step {step_id} {path}: action must be a string or object")
+    kind = action.get("kind")
+    if not isinstance(kind, str) or not kind:
+        raise ValueError(f"step {step_id} {path}: action missing 'kind'")
+    if kind == "condition":
+        if not isinstance(action.get("expr"), str):
+            raise ValueError(f"step {step_id} {path}: condition.expr must be a string")
+        for branch in ("then", "else"):
+            branch_actions = action.get(branch, [])
+            if not isinstance(branch_actions, list):
+                raise ValueError(f"step {step_id} {path}.{branch}: must be a list")
+            for sub_idx, sub in enumerate(branch_actions):
+                validate_action(sub, step_id=step_id, path=f"{path}.{branch}[{sub_idx}]")
+
+
 def validate_runtime3_document(document: dict[str, Any]) -> None:
     if document.get("schema_version") != "zacus.runtime3.v1":
         raise ValueError("schema_version must be zacus.runtime3.v1")
@@ -238,6 +278,11 @@ def validate_runtime3_document(document: dict[str, Any]) -> None:
         if step_id in step_ids:
             raise ValueError(f"duplicate step id: {step_id}")
         step_ids.add(step_id)
+        actions = step.get("actions", [])
+        if not isinstance(actions, list):
+            raise ValueError(f"step {step_id} actions must be a list")
+        for idx, action in enumerate(actions):
+            validate_action(action, step_id=step_id, path=f"actions[{idx}]")
         transitions = step.get("transitions", [])
         if not isinstance(transitions, list):
             raise ValueError(f"step {step_id} transitions must be a list")