phase 3

core/api/detect/config.py

@@ -64,6 +64,22 @@ def list_profiles():
     return [{"name": name} for name in _PROFILES]
 
 
+@router.get("/config/profiles/{profile_name}/pipeline")
+def get_pipeline_config(profile_name: str):
+    """Return the pipeline composition for a profile."""
+    from detect.profiles import get_profile
+    from fastapi import HTTPException
+    from dataclasses import asdict
+
+    try:
+        profile = get_profile(profile_name)
+    except ValueError:
+        raise HTTPException(status_code=404, detail=f"Unknown profile: {profile_name}")
+
+    config = profile.pipeline_config()
+    return asdict(config)
+
+
 @router.get("/config/stages", response_model=list[StageConfigInfo])
 def list_stage_configs():
     """Return the stage palette with config field metadata for the editor."""

core/api/detect/run.py

@@ -88,7 +88,7 @@ def run_pipeline(req: RunRequest):
         log_level=req.log_level,
     )
 
-    pipeline = get_pipeline(checkpoint=req.checkpoint)
+    pipeline = get_pipeline(checkpoint=req.checkpoint, profile_name=req.profile_name)
 
     initial_state = DetectState(
         video_path=local_path,

core/schema/models/__init__.py

@@ -35,6 +35,7 @@ from .detect import DETECT_VIEWS  # noqa: F401 — discovered by modelgen generi
 from .inference import INFERENCE_VIEWS  # noqa: F401 — GPU inference server API types
 from .ui_state import UI_STATE_VIEWS  # noqa: F401 — UI store state types
 from .stages import StageConfigField, StageIO, StageDefinition, STAGE_VIEWS  # noqa: F401
+from .pipeline_config import StageRef, Edge, PipelineConfig, PIPELINE_CONFIG_VIEWS  # noqa: F401
 from .detect_api import RunRequest, RunResponse, DETECT_API_VIEWS  # noqa: F401
 from .views import ChunkEvent, ChunkOutputFile, PipelineStats, WorkerEvent
 from .sources import ChunkInfo, SourceJob, SourceType

core/schema/models/pipeline_config.py

@@ -0,0 +1,46 @@
+"""
+Pipeline composition config — source of truth for graph topology.
+
+Defines what stages run, in what order, with what branching.
+Belongs to a profile. Persisted as JSONB.
+
+The execution strategy (serial, parallel, distributed) is separate —
+the runner reads this config and flattens it into a sequence for now.
+"""
+
+from dataclasses import dataclass, field
+from typing import Any, Dict, List, Optional
+
+
+@dataclass
+class StageRef:
+    """Reference to a stage in the pipeline graph."""
+    name: str                          # stage name (matches StageDefinition.name)
+    branch: str = "trunk"              # which branch this belongs to
+    execution_target: str = "local"    # local | gpu | lambda | gcp
+
+
+@dataclass
+class Edge:
+    """Connection between stages in the graph."""
+    source: str        # stage name
+    target: str        # stage name
+    condition: str = ""  # empty = unconditional, otherwise a routing rule key
+
+
+@dataclass
+class PipelineConfig:
+    """
+    Pipeline graph topology + routing rules.
+
+    Holder model — stages/edges define the graph shape,
+    routing_rules is a JSONB blob for decision tree logic.
+    """
+    name: str
+    profile_name: str
+    stages: List[StageRef] = field(default_factory=list)
+    edges: List[Edge] = field(default_factory=list)
+    routing_rules: Dict[str, Any] = field(default_factory=dict)
+
+
+PIPELINE_CONFIG_VIEWS = [StageRef, Edge, PipelineConfig]

detect/checkpoint/__init__.py

@@ -5,6 +5,7 @@ Checkpoint system — Timeline + Checkpoint tree.
         frames.py      — frame image S3 upload/download
         storage.py     — Timeline + Checkpoint (Postgres + MinIO)
         replay.py      — replay (TODO: migrate to new model)
+        runner_bridge.py — checkpoint hook for PipelineRunner
 """
 
 from .storage import (
@@ -15,3 +16,4 @@ from .storage import (
     load_stage_output,
 )
 from .frames import save_frames, load_frames
+from .runner_bridge import checkpoint_after_stage, reset_checkpoint_state

detect/checkpoint/runner_bridge.py

@@ -0,0 +1,64 @@
+"""
+Runner bridge — checkpoint hook called by PipelineRunner after each stage.
+
+Owns the per-job state (frame manifest cache, checkpoint chain) that
+the runner shouldn't know about.
+"""
+
+from __future__ import annotations
+
+import logging
+
+logger = logging.getLogger(__name__)
+
+# Per-job state
+_frames_manifest: dict[str, dict[int, str]] = {}
+_latest_checkpoint: dict[str, str] = {}
+
+
+def reset_checkpoint_state(job_id: str):
+    """Clean up per-job checkpoint state. Called when pipeline finishes."""
+    _frames_manifest.pop(job_id, None)
+    _latest_checkpoint.pop(job_id, None)
+
+
+def checkpoint_after_stage(job_id: str, stage_name: str, state: dict, result: dict):
+    """
+    Save a checkpoint after a stage completes.
+
+    Called by the runner. Handles:
+    - Frame upload (once, on first stage)
+    - Stage output serialization (via stage registry)
+    - Checkpoint chain (parent → child)
+    """
+    if not job_id:
+        return
+
+    from .storage import save_stage_output
+    from .frames import save_frames
+    from detect.stages.base import _REGISTRY
+
+    merged = {**state, **result}
+
+    # Save frames once (first stage that produces them)
+    manifest = _frames_manifest.get(job_id)
+    if manifest is None and stage_name == "extract_frames":
+        manifest = save_frames(job_id, merged.get("frames", []))
+        _frames_manifest[job_id] = manifest
+
+    # Serialize stage output using the stage's serialize_fn if available
+    stage_cls = _REGISTRY.get(stage_name)
+    serialize_fn = getattr(getattr(stage_cls, "definition", None), "serialize_fn", None)
+    if serialize_fn:
+        output_json = serialize_fn(merged, job_id)
+    else:
+        output_json = {}
+
+    parent_id = _latest_checkpoint.get(job_id)
+    new_checkpoint_id = save_stage_output(
+        timeline_id=job_id,
+        parent_checkpoint_id=parent_id,
+        stage_name=stage_name,
+        output_json=output_json,
+    )
+    _latest_checkpoint[job_id] = new_checkpoint_id

detect/graph/__init__.py

@@ -4,12 +4,13 @@ Detection pipeline graph.
     detect/graph/
         nodes.py    — node functions (one per stage)
         events.py   — graph_update SSE emission
-        runner.py   — pipeline execution (LangGraph wrapper, checkpoint, cancel, pause)
+        runner.py   — PipelineRunner (config-driven, checkpoint, cancel, pause)
 """
 
 from .nodes import NODES, NODE_FUNCTIONS
 from .runner import (
     PipelineCancelled,
+    PipelineRunner,
     build_graph,
     clear_cancel_check,
     clear_pause,
@@ -28,6 +29,7 @@ __all__ = [
     "NODES",
     "NODE_FUNCTIONS",
     "PipelineCancelled",
+    "PipelineRunner",
     "build_graph",
     "get_pipeline",
     "set_cancel_check",

detect/graph/runner.py

@@ -1,8 +1,10 @@
 """
-Pipeline runner — executes stages sequentially with checkpointing and cancellation.
+Pipeline runner — executes stages sequentially with checkpointing,
+cancellation, and pause/resume.
 
-Currently wraps LangGraph for execution. Will be replaced with a lean
+Reads PipelineConfig from the profile to determine what stages to run.
-custom runner in Phase 3, with an executor socket for distributed dispatch.
+Flattens the graph into a linear sequence for now (serial execution).
+Executor socket: all stages run via LocalExecutor (call function directly).
 """
 
 from __future__ import annotations
@@ -11,19 +13,14 @@ import logging
 import os
 import threading
 
-from langgraph.graph import END, StateGraph
+from core.schema.models.pipeline_config import PipelineConfig
-
 from detect.state import DetectState
 from .nodes import NODES, NODE_FUNCTIONS
 
 logger = logging.getLogger(__name__)
 
 
-# --- Checkpoint wrapper ---
-
 _CHECKPOINT_ENABLED = os.environ.get("MPR_CHECKPOINT", "").strip() == "1"
-_frames_manifest: dict[str, dict[int, str]] = {}  # job_id → manifest (cached per job)
-_latest_checkpoint: dict[str, str] = {}  # job_id → latest checkpoint_id
 
 
 class PipelineCancelled(Exception):
@@ -53,10 +50,6 @@ def clear_cancel_check(job_id: str):
 
 # ---------------------------------------------------------------------------
 # Pause / Resume / Step — checked after each node completes
-#
-# _pause_gate: threading.Event per job. When cleared, the runner blocks.
-#              When set, the runner proceeds to the next node.
-# _pause_after_stage: if True, automatically clear the gate after each node.
 # ---------------------------------------------------------------------------
 
 _pause_gate: dict[str, threading.Event] = {}
@@ -98,7 +91,7 @@ def step_pipeline(job_id: str):
     _pause_after_stage[job_id] = True
     gate = _pause_gate.get(job_id)
     if gate:
-        gate.set()  # unblock for one stage, _pause_after_stage re-pauses after
+        gate.set()
         logger.info("Pipeline %s stepping", job_id)
 
 
@@ -106,7 +99,6 @@ def set_pause_after_stage(job_id: str, enabled: bool):
     """Toggle pause-after-each-stage mode."""
     _pause_after_stage[job_id] = enabled
     if not enabled:
-        # If disabling, also resume in case we're currently paused
         gate = _pause_gate.get(job_id)
         if gate:
             gate.set()
@@ -124,106 +116,159 @@ def _wait_if_paused(job_id: str, node_name: str):
     if gate is None:
         return
 
-    # If pause-after-stage is on, pause now
     if _pause_after_stage.get(job_id, False):
         gate.clear()
         from detect import emit
         emit.log(job_id, "Pipeline", "INFO", f"Paused after {node_name}")
 
-    # Block until gate is set (resume/step) or cancelled
     while not gate.wait(timeout=0.5):
         check = _cancel_check.get(job_id)
         if check and check():
             raise PipelineCancelled(f"Cancelled while paused before next stage")
 
 
-def _checkpointing_node(node_name: str, node_fn):
-    """Wrap a node function to auto-checkpoint after completion."""
 
-    def wrapper(state: DetectState) -> dict:
+
+# ---------------------------------------------------------------------------
+# Pipeline Runner
+# ---------------------------------------------------------------------------
+
+# Node function lookup — maps stage name to callable
+_NODE_FN_MAP: dict[str, callable] = {name: fn for name, fn in NODE_FUNCTIONS}
+
+
+def _flatten_config(config: PipelineConfig, start_from: str | None = None) -> list[str]:
+    """
+    Flatten a PipelineConfig into a linear stage sequence.
+
+    For now: topological sort via edges. Falls back to stage order if no edges.
+    Respects start_from for replay (skip stages before it).
+    """
+    if not config.edges:
+        # No edges defined — use stage order as-is
+        names = [s.name for s in config.stages]
+    else:
+        # Topological sort from edges
+        graph: dict[str, list[str]] = {}
+        in_degree: dict[str, int] = {}
+        stage_names = {s.name for s in config.stages}
+
+        for name in stage_names:
+            graph[name] = []
+            in_degree[name] = 0
+
+        for edge in config.edges:
+            if edge.source in stage_names and edge.target in stage_names:
+                graph[edge.source].append(edge.target)
+                in_degree[edge.target] = in_degree.get(edge.target, 0) + 1
+
+        # Kahn's algorithm
+        queue = [n for n in stage_names if in_degree.get(n, 0) == 0]
+        # Stable sort: prefer order from config.stages
+        stage_order = {s.name: i for i, s in enumerate(config.stages)}
+        queue.sort(key=lambda n: stage_order.get(n, 999))
+
+        names = []
+        while queue:
+            node = queue.pop(0)
+            names.append(node)
+            for neighbor in graph.get(node, []):
+                in_degree[neighbor] -= 1
+                if in_degree[neighbor] == 0:
+                    queue.append(neighbor)
+            queue.sort(key=lambda n: stage_order.get(n, 999))
+
+    if start_from:
+        try:
+            idx = names.index(start_from)
+            names = names[idx:]
+        except ValueError:
+            raise ValueError(f"Stage {start_from!r} not in pipeline config")
+
+    return names
+
+
+class PipelineRunner:
+    """
+    Executes a pipeline defined by PipelineConfig.
+
+    Runs stages sequentially (flattened). Each stage:
+    1. Check cancel
+    2. Run node function (via executor — local for now)
+    3. Merge result into state
+    4. Checkpoint (if enabled)
+    5. Check pause
+
+    Executor socket: currently calls node functions directly.
+    Future: dispatch to LocalExecutor / GrpcExecutor / LambdaExecutor
+    based on StageRef.execution_target.
+    """
+
+    def __init__(
+        self,
+        config: PipelineConfig,
+        checkpoint: bool = False,
+        start_from: str | None = None,
+    ):
+        self.config = config
+        self.do_checkpoint = checkpoint
+        self.stage_sequence = _flatten_config(config, start_from)
+
+    def invoke(self, state: DetectState) -> DetectState:
+        """Run the pipeline on the given state. Returns final state."""
+        for stage_name in self.stage_sequence:
             job_id = state.get("job_id", "")
+
+            # 1. Cancel check
             check = _cancel_check.get(job_id)
             if check and check():
-            raise PipelineCancelled(f"Cancelled before {node_name}")
+                raise PipelineCancelled(f"Cancelled before {stage_name}")
+
+            # 2. Run node function
+            node_fn = _NODE_FN_MAP.get(stage_name)
+            if node_fn is None:
+                logger.warning("No node function for stage %s, skipping", stage_name)
+                continue
 
             result = node_fn(state)
 
-        job_id = state.get("job_id", "")
+            # 3. Merge result into state
-        if not job_id:
+            state.update(result)
-            return result
 
-        from detect.checkpoint import save_stage_output, save_frames
+            # 4. Checkpoint
-        from detect.stages.base import _REGISTRY
+            if self.do_checkpoint:
+                from detect.checkpoint import checkpoint_after_stage
+                checkpoint_after_stage(job_id, stage_name, state, result)
 
-        merged = {**state, **result}
+            # 5. Pause check
+            _wait_if_paused(job_id, stage_name)
 
-        # Save frames once (first node), reuse manifest after
+        return state
-        manifest = _frames_manifest.get(job_id)
-        if manifest is None and node_name == "extract_frames":
-            manifest = save_frames(job_id, merged.get("frames", []))
-            _frames_manifest[job_id] = manifest
-
-        # Serialize stage output using the stage's serialize_fn if available
-        stage_cls = _REGISTRY.get(node_name)
-        serialize_fn = getattr(getattr(stage_cls, "definition", None), "serialize_fn", None)
-        if serialize_fn:
-            output_json = serialize_fn(merged, job_id)
-        else:
-            output_json = {}
-
-        parent_id = _latest_checkpoint.get(job_id)
-        new_checkpoint_id = save_stage_output(
-            timeline_id=job_id,
-            parent_checkpoint_id=parent_id,
-            stage_name=node_name,
-            output_json=output_json,
-        )
-        _latest_checkpoint[job_id] = new_checkpoint_id
-
-        # Pause check — blocks if paused, respects cancel while waiting
-        _wait_if_paused(job_id, node_name)
-
-        return result
-
-    wrapper.__name__ = node_fn.__name__
-    return wrapper
 
 
-# --- Graph construction ---
+# ---------------------------------------------------------------------------
+# Public API — backwards compatible with old get_pipeline/build_graph
+# ---------------------------------------------------------------------------
 
-def build_graph(checkpoint: bool | None = None, start_from: str | None = None) -> StateGraph:
+def get_pipeline(
-    """
+    checkpoint: bool | None = None,
-    Build the pipeline graph.
+    profile_name: str = "soccer_broadcast",
+    start_from: str | None = None,
+) -> PipelineRunner:
+    """Return a PipelineRunner for the given profile."""
+    from detect.profiles import get_profile
 
-    checkpoint: enable auto-checkpointing (default: MPR_CHECKPOINT env var)
-    start_from: skip nodes before this stage (for replay)
-    """
     do_checkpoint = checkpoint if checkpoint is not None else _CHECKPOINT_ENABLED
+    profile = get_profile(profile_name)
+    config = profile.pipeline_config()
 
-    graph = StateGraph(DetectState)
+    return PipelineRunner(
-
+        config=config,
-    # Filter to start_from if replaying
+        checkpoint=do_checkpoint,
-    node_pairs = NODE_FUNCTIONS
+        start_from=start_from,
-    if start_from:
+    )
-        start_idx = next(i for i, (name, _) in enumerate(NODE_FUNCTIONS) if name == start_from)
-        node_pairs = NODE_FUNCTIONS[start_idx:]
-
-    for name, fn in node_pairs:
-        wrapped = _checkpointing_node(name, fn) if do_checkpoint else fn
-        graph.add_node(name, wrapped)
-
-    # Wire edges
-    entry = node_pairs[0][0]
-    graph.set_entry_point(entry)
-
-    for i in range(len(node_pairs) - 1):
-        graph.add_edge(node_pairs[i][0], node_pairs[i + 1][0])
-
-    graph.add_edge(node_pairs[-1][0], END)
-
-    return graph
 
 
-def get_pipeline(checkpoint: bool | None = None):
+def build_graph(checkpoint: bool | None = None, start_from: str | None = None):
-    """Return a compiled, runnable pipeline."""
+    """Backwards-compatible wrapper. Returns a PipelineRunner."""
-    return build_graph(checkpoint=checkpoint).compile()
+    return get_pipeline(checkpoint=checkpoint, start_from=start_from)

detect/profiles/base.py

@@ -1,17 +1,20 @@
 """
 ContentTypeProfile protocol and config dataclasses.
 
-The pipeline graph is fixed — what varies per content type is configuration
+Each profile defines the pipeline topology (as a JSONB blob), stage configs,
-and hooks. Each profile provides stage configs, a brand dictionary,
+brand dictionary, VLM prompt templates, and aggregation strategy.
-VLM prompt templates, and an aggregation strategy.
+
+When profiles are persisted, the pipeline field is a JSONB column.
+For now, profiles are code-only and pipeline_config() returns a hardcoded value.
 """
 
 from __future__ import annotations
 
 from dataclasses import dataclass, field
-from typing import Protocol
+from typing import Any, Dict, Protocol
 
 from detect.models import BrandDetection, DetectionReport
+from core.schema.models.pipeline_config import PipelineConfig, StageRef, Edge
 
 
 @dataclass
@@ -64,9 +67,24 @@ class CropContext:
     position_hint: str = ""
 
 
+def pipeline_config_from_dict(data: Dict[str, Any]) -> PipelineConfig:
+    """Deserialize a PipelineConfig from a JSONB dict."""
+    stages = [StageRef(**s) for s in data.get("stages", [])]
+    edges = [Edge(**e) for e in data.get("edges", [])]
+    return PipelineConfig(
+        name=data.get("name", ""),
+        profile_name=data.get("profile_name", ""),
+        stages=stages,
+        edges=edges,
+        routing_rules=data.get("routing_rules", {}),
+    )
+
+
 class ContentTypeProfile(Protocol):
     name: str
+    pipeline: Dict[str, Any]  # JSONB blob — PipelineConfig shape
 
+    def pipeline_config(self) -> PipelineConfig: ...
     def frame_extraction_config(self) -> FrameExtractionConfig: ...
     def scene_filter_config(self) -> SceneFilterConfig: ...
     def region_analysis_config(self) -> RegionAnalysisConfig: ...

detect/profiles/soccer.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from core.schema.models.pipeline_config import PipelineConfig
 from detect.models import BrandDetection, BrandStats, DetectionReport, PipelineStats
 
 from .base import (
@@ -12,12 +13,46 @@ from .base import (
     RegionAnalysisConfig,
     ResolverConfig,
     SceneFilterConfig,
+    pipeline_config_from_dict,
 )
 
 
 class SoccerBroadcastProfile:
     name = "soccer_broadcast"
 
+    # Pipeline topology as JSONB — will be a DB field when profiles are persisted
+    pipeline = {
+        "name": "soccer_broadcast",
+        "profile_name": "soccer_broadcast",
+        "stages": [
+            {"name": "extract_frames", "branch": "trunk"},
+            {"name": "filter_scenes", "branch": "trunk"},
+            {"name": "detect_edges", "branch": "hoarding"},
+            {"name": "detect_objects", "branch": "objects"},
+            {"name": "preprocess"},
+            {"name": "run_ocr"},
+            {"name": "match_brands"},
+            {"name": "escalate_vlm"},
+            {"name": "escalate_cloud"},
+            {"name": "compile_report"},
+        ],
+        "edges": [
+            {"source": "extract_frames", "target": "filter_scenes"},
+            {"source": "filter_scenes", "target": "detect_edges"},
+            {"source": "filter_scenes", "target": "detect_objects"},
+            {"source": "detect_edges", "target": "preprocess"},
+            {"source": "detect_objects", "target": "preprocess"},
+            {"source": "preprocess", "target": "run_ocr"},
+            {"source": "run_ocr", "target": "match_brands"},
+            {"source": "match_brands", "target": "escalate_vlm"},
+            {"source": "escalate_vlm", "target": "escalate_cloud"},
+            {"source": "escalate_cloud", "target": "compile_report"},
+        ],
+    }
+
+    def pipeline_config(self) -> PipelineConfig:
+        return pipeline_config_from_dict(self.pipeline)
+
     def frame_extraction_config(self) -> FrameExtractionConfig:
         return FrameExtractionConfig(fps=2.0, max_frames=500)
 

tests/detect/test_graph.py

@@ -1,4 +1,4 @@
-"""Tests for the LangGraph detection pipeline."""
+"""Tests for the detection pipeline runner."""
 
 import os
 
@@ -33,9 +33,9 @@ def test_graph_compiles():
 
 
 def test_graph_has_all_nodes():
-    graph = build_graph()
+    runner = build_graph()
     for node in NODES:
-        assert node in graph.nodes
+        assert node in runner.stage_sequence
 
 
 @requires_inference

ui/detection-app/src/panels/PipelineGraphPanel.vue

@@ -1,10 +1,17 @@
 <script setup lang="ts">
-import { ref, watch, computed } from 'vue'
+import { ref, watch, computed, onMounted } from 'vue'
 import { Panel, GraphRenderer } from 'mpr-ui-framework'
 import type { GraphNode, GraphMode, DataSource } from 'mpr-ui-framework'
 import { usePipelineStore } from '../stores/pipeline'
 import { useStageRegistry } from '../composables/useStageRegistry'
 
+interface PipelineConfigResponse {
+  name: string
+  profile_name: string
+  stages: { name: string; branch: string; execution_target: string }[]
+  edges: { source: string; target: string; condition: string }[]
+}
+
 const props = defineProps<{
   source: DataSource
   status?: 'idle' | 'live' | 'processing' | 'error'
@@ -14,6 +21,19 @@ const pipeline = usePipelineStore()
 const { stageNames, editableStages } = useStageRegistry()
 
 const nodes = ref<GraphNode[]>([])
+const pipelineConfig = ref<PipelineConfigResponse | null>(null)
+
+// Fetch pipeline config for a profile
+async function fetchPipelineConfig(profileName: string) {
+  try {
+    const resp = await fetch(`/api/detect/config/profiles/${profileName}/pipeline`)
+    if (!resp.ok) return
+    pipelineConfig.value = await resp.json()
+  } catch { /* ignore */ }
+}
+
+// Load default profile config on mount
+onMounted(() => fetchPipelineConfig('soccer_broadcast'))
 
 // Derive graph mode from pipeline layout mode
 const graphMode = computed<GraphMode>(() => {
@@ -23,27 +43,20 @@ const graphMode = computed<GraphMode>(() => {
   return 'observe'
 })
 
-// Initialize nodes from registry when it loads
+// Initialize nodes from pipeline config when it loads
+watch(pipelineConfig, (config) => {
+  if (config && config.stages.length > 0 && nodes.value.length === 0) {
+    nodes.value = config.stages.map((s) => ({ id: s.name, status: 'pending' }))
+  }
+}, { immediate: true })
+
+// Fallback: init from registry if no config loaded
 watch(stageNames, (names) => {
   if (names.length > 0 && nodes.value.length === 0) {
     nodes.value = names.map((id) => ({ id, status: 'pending' }))
   }
 }, { immediate: true })
 
-// Source selector: placeholders until a chunk is selected, then real stage names
-const displayNodes = computed<GraphNode[]>(() => {
-  if (pipeline.layoutMode === 'source_selector') {
-    if (pipeline.sourceHasSelection) {
-      return stageNames.value.map((id) => ({ id, status: 'pending' as const }))
-    }
-    return Array.from({ length: 10 }, (_, i) => ({
-      id: `_placeholder_${i}`,
-      status: 'placeholder' as const,
-    }))
-  }
-  return nodes.value
-})
-
 props.source.on<{ nodes: GraphNode[] }>('graph_update', (e) => {
   nodes.value = e.nodes
 })
@@ -63,6 +76,25 @@ props.source.on<{ report?: { status?: string } }>('job_complete', (e) => {
   }
 })
 
+// Source selector: placeholders until a chunk is selected, then real stage names
+const configStageNames = computed(() =>
+  pipelineConfig.value?.stages.map(s => s.name) ?? stageNames.value
+)
+
+const displayNodes = computed<GraphNode[]>(() => {
+  if (pipeline.layoutMode === 'source_selector') {
+    if (pipeline.sourceHasSelection) {
+      return configStageNames.value.map((id) => ({ id, status: 'pending' as const }))
+    }
+    const count = configStageNames.value.length || 10
+    return Array.from({ length: count }, (_, i) => ({
+      id: `_placeholder_${i}`,
+      status: 'placeholder' as const,
+    }))
+  }
+  return nodes.value
+})
+
 function onOpenRegionEditor(stage: string) {
   pipeline.openBBoxEditor(stage)
 }