fix(vwb): propage l'image d'ancre aux substeps compound à l'import (SP-1/U-B)

Les actions compound passaient par _convert_compound_substep qui ne lisait
jamais l'image d'ancre du parent -> substeps anchor_id NULL, "Ancre requise"
sans image dans le VWB. On pose desormais l'ancre du parent (meme fallback que
la branche action simple) sur le 1er substep cliquable uniquement.

Test: test_learned_workflow_bridge.py (TDD, RED->GREEN).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

visual_workflow_builder/backend/services/learned_workflow_bridge.py

@@ -166,11 +166,30 @@ def convert_learned_to_vwb_steps(
                 )
                 continue
 
+            # Image d'ancre du parent : à poser sur le 1er substep cliquable.
+            # Les actions simples l'obtiennent déjà (branche `else` plus bas) ;
+            # les compound ne la propageaient pas → substeps anchor_id NULL.
+            compound_anchor_b64 = (
+                target.get("anchor_image_base64")
+                or target.get("screenshot")
+                or (target.get("context_hints") or {}).get("anchor_image_base64")
+            )
+            compound_anchor_attached = False
+
             for sub_idx, sub in enumerate(sub_steps):
                 sub_type = sub.get("type", "unknown")
                 sub_vwb_type, sub_params = _convert_compound_substep(
                     sub_type, sub, target
                 )
+                # Poser l'ancre du parent sur le 1er substep cliquable uniquement
+                # (éviter de la dupliquer sur les N substeps).
+                if (
+                    compound_anchor_b64
+                    and not compound_anchor_attached
+                    and sub_vwb_type in ("click_anchor", "double_click_anchor", "right_click_anchor")
+                ):
+                    sub_params["_anchor_image_base64"] = compound_anchor_b64
+                    compound_anchor_attached = True
                 label = _build_step_label(sub_vwb_type, sub_params, from_name, to_name)
                 steps.append({
                     "action_type": sub_vwb_type,

visual_workflow_builder/backend/test_learned_workflow_bridge.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+"""
+Test TDD — propagation de l'image d'ancre aux substeps *compound* (SP-1 / U-B).
+
+Bug : `convert_learned_to_vwb_steps` ne propage `anchor_image_base64` qu'aux
+actions simples (branche L226-233). Les substeps des actions *compound*
+(majoritaires côté Léa) passent par `_convert_compound_substep` qui ne lit
+jamais l'ancre → `anchor_id NULL` → "Ancre requise" sans image dans le VWB.
+
+Cible du fix : poser l'image d'ancre du parent sur le 1er substep cliquable.
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+
+from services.learned_workflow_bridge import convert_learned_to_vwb_steps
+
+_CLICK_TYPES = ("click_anchor", "double_click_anchor", "right_click_anchor")
+
+
+def _compound_workflow_with_anchor(b64: str) -> dict:
+    """Workflow core minimal : un edge compound dont la cible porte une image
+    d'ancre dans `context_hints`, avec un substep cliquable suivi d'une saisie."""
+    return {
+        "workflow_id": "wf_test_compound_anchor",
+        "name": "Test compound anchor",
+        "entry_nodes": ["n1"],
+        "nodes": [
+            {"node_id": "n1", "name": "Start"},
+            {"node_id": "n2", "name": "End"},
+        ],
+        "edges": [
+            {
+                "edge_id": "e1",
+                "from_node": "n1",
+                "to_node": "n2",
+                "action": {
+                    "type": "compound",
+                    "target": {
+                        "by_text": "Fichier",
+                        "context_hints": {"anchor_image_base64": b64},
+                    },
+                    "parameters": {
+                        "steps": [
+                            {"type": "mouse_click", "pos": [0.5, 0.5], "button": "left"},
+                            {"type": "text_input", "text": "bonjour"},
+                        ]
+                    },
+                },
+            }
+        ],
+    }
+
+
+def test_compound_substep_inherits_anchor_image():
+    """Le 1er substep cliquable d'un compound doit hériter de l'image d'ancre du parent."""
+    b64 = "ZmFrZV9hbmNob3I="  # "fake_anchor" encodé base64
+    _meta, steps, _warnings = convert_learned_to_vwb_steps(
+        _compound_workflow_with_anchor(b64)
+    )
+
+    clickable = [s for s in steps if s["action_type"] in _CLICK_TYPES]
+    assert clickable, "le compound aurait dû produire au moins un step cliquable"
+    assert clickable[0]["parameters"].get("_anchor_image_base64") == b64, (
+        "le 1er substep cliquable doit hériter de l'image d'ancre du parent "
+        "(target.context_hints.anchor_image_base64)"
+    )