diff --git a/core/api/detect/config.py b/core/api/detect/config.py
index 2436e61..b41de84 100644
--- a/core/api/detect/config.py
+++ b/core/api/detect/config.py
@@ -30,12 +30,21 @@ class ConfigUpdate(BaseModel):
     preprocessing: dict | None = None
 
 
+class StageOutputHintInfo(BaseModel):
+    key: str
+    type: str
+    label: str = ""
+    default_opacity: float = 0.5
+    src_format: str = "png"
+
+
 class StageConfigInfo(BaseModel):
     name: str
     label: str
     description: str
     category: str
     config_fields: list[dict]
+    output_hints: list[StageOutputHintInfo] = []
     reads: list[str]
     writes: list[str]
 
@@ -121,6 +130,13 @@ def _stage_to_info(stage) -> StageConfigInfo:
             }
             for f in stage.config_fields
         ],
+        output_hints=[
+            StageOutputHintInfo(
+                key=h.key, type=h.type, label=h.label,
+                default_opacity=h.default_opacity, src_format=h.src_format,
+            )
+            for h in getattr(stage, "output_hints", [])
+        ],
         reads=stage.io.reads,
         writes=stage.io.writes,
     )
diff --git a/core/api/detect/replay.py b/core/api/detect/replay.py
index 41e75fb..4f4fff9 100644
--- a/core/api/detect/replay.py
+++ b/core/api/detect/replay.py
@@ -41,34 +41,24 @@ class ScenarioInfo(BaseModel):
 
 
 class ReplayRequest(BaseModel):
-    timeline_id: str
+    job_id: str
     start_stage: str
     config_overrides: dict | None = None
 
 
 class ReplayResponse(BaseModel):
     status: str
-    timeline_id: str
+    job_id: str
+    replay_job_id: str
     start_stage: str
     detections: int = 0
     brands_found: int = 0
 
 
-class RetryRequest(BaseModel):
-    timeline_id: str
-    config_overrides: dict | None = None
-    start_stage: str = "escalate_vlm"
-    schedule_seconds: float | None = None  # delay before execution (off-peak)
-
-
-class RetryResponse(BaseModel):
-    status: str
-    task_id: str
-    timeline_id: str
 
 
 class ReplaySingleStageRequest(BaseModel):
-    timeline_id: str
+    job_id: str
     stage: str
     frame_refs: list[int] | None = None
     config_overrides: dict | None = None
@@ -103,16 +93,24 @@ class ReplaySingleStageResponse(BaseModel):
 # --- Endpoints ---
 
 @router.get("/checkpoints/{timeline_id}")
-def list_checkpoints(timeline_id: str) -> list[CheckpointInfo]:
-    """List available checkpoint stages for a job."""
-    from core.detect.checkpoint import list_checkpoints as _list
+def list_checkpoints_endpoint(timeline_id: str) -> list[CheckpointInfo]:
+    """List available checkpoint stages for a timeline."""
+    from core.detect.checkpoint.storage import get_checkpoints_for_timeline
 
     try:
-        stages = _list(timeline_id)
+        checkpoints = get_checkpoints_for_timeline(timeline_id)
     except Exception as e:
-        raise HTTPException(status_code=404, detail=f"No checkpoints for job {timeline_id}: {e}")
+        raise HTTPException(status_code=404, detail=f"No checkpoints for timeline {timeline_id}: {e}")
 
-    result = [CheckpointInfo(stage=s) for s in stages]
+    result = [
+        CheckpointInfo(
+            stage=c["stage_name"],
+            is_scenario=c.get("is_scenario", False),
+            scenario_label=c.get("scenario_label", ""),
+        )
+        for c in checkpoints
+        if c["stage_name"]
+    ]
     return result
 
 
@@ -211,11 +209,11 @@ def list_scenarios_endpoint():
 @router.post("/replay", response_model=ReplayResponse)
 def replay(req: ReplayRequest):
     """Replay pipeline from a specific stage with optional config overrides."""
-    from core.detect.checkpoint import replay_from
+    from core.detect.checkpoint.replay import replay_from
 
     try:
         result = replay_from(
-            timeline_id=req.timeline_id,
+            job_id=req.job_id,
             start_stage=req.start_stage,
             config_overrides=req.config_overrides,
         )
@@ -230,7 +228,8 @@ def replay(req: ReplayRequest):
 
     response = ReplayResponse(
         status="completed",
-        timeline_id=req.timeline_id,
+        job_id=req.job_id,
+        replay_job_id=result.get("job_id", ""),
         start_stage=req.start_stage,
         detections=len(detections),
         brands_found=brands_found,
@@ -238,29 +237,6 @@ def replay(req: ReplayRequest):
     return response
 
 
-@router.post("/retry", response_model=RetryResponse)
-def retry(req: RetryRequest):
-    """Queue an async retry of unresolved candidates with different config."""
-    from core.detect.checkpoint.tasks import retry_candidates
-
-    kwargs = {
-        "timeline_id": req.timeline_id,
-        "config_overrides": req.config_overrides,
-        "start_stage": req.start_stage,
-    }
-
-    if req.schedule_seconds:
-        task = retry_candidates.apply_async(kwargs=kwargs, countdown=req.schedule_seconds)
-    else:
-        task = retry_candidates.delay(**kwargs)
-
-    response = RetryResponse(
-        status="queued",
-        task_id=task.id,
-        timeline_id=req.timeline_id,
-    )
-    return response
-
 
 @router.post("/replay-stage", response_model=ReplaySingleStageResponse)
 def replay_single_stage(req: ReplaySingleStageRequest):
@@ -269,7 +245,7 @@ def replay_single_stage(req: ReplaySingleStageRequest):
 
     try:
         result = _replay(
-            timeline_id=req.timeline_id,
+            job_id=req.job_id,
             stage=req.stage,
             frame_refs=req.frame_refs,
             config_overrides=req.config_overrides,
@@ -324,6 +300,151 @@ def _gpu_url() -> str:
     return url.rstrip("/")
 
 
+# --- Overlay cache — save/load debug overlay images ---
+
+
+class SaveOverlaysRequest(BaseModel):
+    timeline_id: str
+    job_id: str
+    stage: str
+    seq: int
+    overlays: dict[str, str]  # {overlay_key: base64_png}
+
+
+@router.post("/overlays")
+def save_overlays_endpoint(req: SaveOverlaysRequest):
+    """Save debug overlay images to blob storage cache."""
+    from core.detect.checkpoint.frames import save_overlays
+
+    save_overlays(req.timeline_id, req.job_id, req.stage, req.seq, req.overlays)
+    return {"status": "saved", "count": len(req.overlays)}
+
+
+@router.get("/overlays/{timeline_id}/{job_id}/{stage}/{seq}")
+def load_overlays_endpoint(timeline_id: str, job_id: str, stage: str, seq: int):
+    """Load cached debug overlay images."""
+    from core.detect.checkpoint.frames import load_overlays
+
+    overlays = load_overlays(timeline_id, job_id, stage, seq)
+    return {"overlays": overlays or {}}
+
+
+def _generate_debug_overlays(job_id: str, stage: str, frame) -> dict[str, str] | None:
+    """Generate debug overlay images for a single frame."""
+    import os
+
+    inference_url = os.environ.get("INFERENCE_URL")
+
+    if stage == "detect_edges":
+        from core.detect.profile import get_profile, get_stage_config
+        from core.detect.stages.models import RegionAnalysisConfig
+        from core.db.connection import get_session
+        from core.db.job import get_job
+        from uuid import UUID
+
+        with get_session() as session:
+            job = get_job(session, UUID(job_id))
+        if not job:
+            return None
+
+        profile = get_profile(job.profile_name)
+        config = RegionAnalysisConfig(**get_stage_config(profile, "detect_edges"))
+
+        if inference_url:
+            from core.detect.inference import InferenceClient
+            client = InferenceClient(base_url=inference_url, job_id=job_id)
+            dr = client.detect_edges_debug(
+                image=frame.image,
+                edge_canny_low=config.edge_canny_low,
+                edge_canny_high=config.edge_canny_high,
+                edge_hough_threshold=config.edge_hough_threshold,
+                edge_hough_min_length=config.edge_hough_min_length,
+                edge_hough_max_gap=config.edge_hough_max_gap,
+                edge_pair_max_distance=config.edge_pair_max_distance,
+                edge_pair_min_distance=config.edge_pair_min_distance,
+            )
+            return {
+                "edge_overlay_b64": dr.edge_overlay_b64,
+                "lines_overlay_b64": dr.lines_overlay_b64,
+            }
+        else:
+            from core.detect.stages.edge_detector import _load_cv_edges
+            edges_mod = _load_cv_edges()
+            dr = edges_mod.detect_edges_debug(
+                frame.image,
+                canny_low=config.edge_canny_low,
+                canny_high=config.edge_canny_high,
+                hough_threshold=config.edge_hough_threshold,
+                hough_min_length=config.edge_hough_min_length,
+                hough_max_gap=config.edge_hough_max_gap,
+                pair_max_distance=config.edge_pair_max_distance,
+                pair_min_distance=config.edge_pair_min_distance,
+            )
+            return {
+                "edge_overlay_b64": dr["edge_overlay_b64"],
+                "lines_overlay_b64": dr["lines_overlay_b64"],
+            }
+
+    elif stage == "field_segmentation":
+        from core.detect.profile import get_profile, get_stage_config
+        from core.detect.stages.models import FieldSegmentationConfig
+        from core.db.connection import get_session
+        from core.db.job import get_job
+        from uuid import UUID
+
+        with get_session() as session:
+            job = get_job(session, UUID(job_id))
+        if not job:
+            return None
+
+        profile = get_profile(job.profile_name)
+        config = FieldSegmentationConfig(**get_stage_config(profile, "field_segmentation"))
+
+        if inference_url:
+            import httpx, json, base64, io
+            from PIL import Image
+            import numpy as np
+
+            buf = io.BytesIO()
+            Image.fromarray(frame.image).save(buf, format="JPEG", quality=85)
+            img_b64 = base64.b64encode(buf.getvalue()).decode()
+
+            resp = httpx.post(
+                f"{inference_url.rstrip('/')}/segment_field/debug",
+                json={
+                    "image_b64": img_b64,
+                    "hue_low": config.hue_low,
+                    "hue_high": config.hue_high,
+                    "sat_low": config.sat_low,
+                    "sat_high": config.sat_high,
+                    "val_low": config.val_low,
+                    "val_high": config.val_high,
+                    "morph_kernel": config.morph_kernel,
+                    "min_area_ratio": config.min_area_ratio,
+                },
+                timeout=30.0,
+            )
+            if resp.status_code == 200:
+                data = resp.json()
+                return {"mask_overlay_b64": data.get("mask_b64", "")}
+
+        return None
+
+    return None
+
+
+@router.get("/overlays/{timeline_id}/{job_id}/{stage}")
+def list_overlay_frames_endpoint(timeline_id: str, job_id: str, stage: str):
+    """List frame sequences that have cached overlays."""
+    from core.detect.checkpoint.frames import list_overlay_frames
+
+    seqs = list_overlay_frames(timeline_id, job_id, stage)
+    return {"frames": seqs}
+
+
+# --- GPU proxy — thin passthrough to inference server for interactive editor ---
+
+
 @router.post("/gpu/detect_edges")
 async def gpu_detect_edges(request: Request):
     """Proxy to GPU inference server — browser can't reach it directly."""
diff --git a/core/detect/checkpoint/frames.py b/core/detect/checkpoint/frames.py
index 16d0aea..1a7286d 100644
--- a/core/detect/checkpoint/frames.py
+++ b/core/detect/checkpoint/frames.py
@@ -147,6 +147,108 @@ def load_cached_frames_b64(timeline_id: str) -> list[dict]:
     return result
 
 
+# ---------------------------------------------------------------------------
+# Debug overlay storage — per job/stage/frame
+# ---------------------------------------------------------------------------
+
+def _overlay_prefix(timeline_id: str, job_id: str, stage: str) -> str:
+    return f"{CACHE_PREFIX}/{timeline_id}/overlays/{job_id}/{stage}/"
+
+
+def _overlay_key(timeline_id: str, job_id: str, stage: str, seq: int, name: str) -> str:
+    return f"{CACHE_PREFIX}/{timeline_id}/overlays/{job_id}/{stage}/{seq}_{name}.png"
+
+
+def save_overlays(
+    timeline_id: str,
+    job_id: str,
+    stage: str,
+    seq: int,
+    overlays: dict[str, str],
+):
+    """
+    Save debug overlay images (base64 PNG) to blob storage.
+
+    overlays: {overlay_key: base64_png_string}
+    e.g. {"edge_overlay_b64": "iVBOR...", "lines_overlay_b64": "iVBOR..."}
+    """
+    from core.storage.s3 import upload_file
+    import tempfile
+
+    for name, b64_data in overlays.items():
+        key = _overlay_key(timeline_id, job_id, stage, seq, name)
+        raw = base64.b64decode(b64_data)
+
+        with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as tmp:
+            tmp.write(raw)
+            tmp_path = tmp.name
+
+        try:
+            upload_file(tmp_path, BUCKET, key)
+        finally:
+            os.unlink(tmp_path)
+
+    logger.info("Saved %d overlays for timeline %s job %s stage %s frame %d",
+                len(overlays), timeline_id, job_id, stage, seq)
+
+
+def load_overlays(
+    timeline_id: str,
+    job_id: str,
+    stage: str,
+    seq: int,
+) -> dict[str, str] | None:
+    """
+    Load debug overlay images from blob storage as base64 strings.
+
+    Returns {overlay_key: base64_png_string} or None if no overlays cached.
+    """
+    from core.storage.s3 import list_objects, download_to_temp
+
+    prefix = _overlay_prefix(timeline_id, job_id, stage)
+    seq_prefix = f"{seq}_"
+    objects = list_objects(BUCKET, prefix)
+
+    overlays = {}
+    for obj in objects:
+        filename = obj["key"].rsplit("/", 1)[-1]
+        if not filename.startswith(seq_prefix):
+            continue
+        name = filename[len(seq_prefix):].replace(".png", "")
+
+        tmp_path = download_to_temp(BUCKET, obj["key"])
+        try:
+            with open(tmp_path, "rb") as f:
+                overlays[name] = base64.b64encode(f.read()).decode()
+        finally:
+            os.unlink(tmp_path)
+
+    return overlays if overlays else None
+
+
+def list_overlay_frames(
+    timeline_id: str,
+    job_id: str,
+    stage: str,
+) -> list[int]:
+    """List frame sequences that have cached overlays."""
+    from core.storage.s3 import list_objects
+
+    prefix = _overlay_prefix(timeline_id, job_id, stage)
+    objects = list_objects(BUCKET, prefix)
+
+    seqs = set()
+    for obj in objects:
+        filename = obj["key"].rsplit("/", 1)[-1]
+        seq_str = filename.split("_")[0]
+        try:
+            seqs.add(int(seq_str))
+        except ValueError:
+            continue
+
+    return sorted(seqs)
+
+
 def clear_cache(timeline_id: str):
     """Delete the frame cache for a timeline."""
     from core.storage.s3 import delete_objects
diff --git a/core/detect/checkpoint/replay.py b/core/detect/checkpoint/replay.py
index 59fa962..0917303 100644
--- a/core/detect/checkpoint/replay.py
+++ b/core/detect/checkpoint/replay.py
@@ -1,32 +1,88 @@
 """
 Pipeline replay — re-run from any stage with different config.
 
-Loads a checkpoint, applies config overrides, builds a subgraph
-starting from the target stage, and invokes it.
+Loads stage outputs from DB, frames from timeline cache,
+reconstitutes state, and runs from a target stage onward.
+
+Creates a new Job (run_type=REPLAY) for each replay invocation.
 """
 
 from __future__ import annotations
 
 import logging
-
+import os
 import uuid
 
 from core.detect import emit
-# TODO: migrate to Timeline/Branch/Checkpoint model
-# These old functions no longer exist — replay needs rework
-def _not_migrated(*args, **kwargs):
-    raise NotImplementedError("Replay not yet migrated to Timeline/Branch/Checkpoint model")
-
-load_checkpoint = _not_migrated
-list_checkpoints = _not_migrated
-from core.detect.graph import NODES, build_graph
+from core.detect.graph import NODES, get_pipeline
+from core.detect.graph.runner import PipelineRunner
 
 logger = logging.getLogger(__name__)
 
 
+def _build_state_for_replay(
+    job_id: str,
+    up_to_stage: str,
+) -> dict:
+    """
+    Reconstitute pipeline state from a completed job's stage outputs,
+    up to (but not including) the target stage.
 
-# OverrideProfile removed — config overrides are now handled by dict merging
-# in _load_profile() (nodes.py) and replay_single_stage (below).
+    Loads frames from timeline cache + stage outputs from DB.
+    """
+    from .storage import load_stage_outputs_for_job, get_checkpoints_for_job
+    from .frames import load_cached_frames
+    from core.db.connection import get_session
+    from core.db.job import get_job
+
+    # Load the job to get timeline_id and profile
+    with get_session() as session:
+        job = get_job(session, uuid.UUID(job_id))
+    if not job:
+        raise ValueError(f"Job not found: {job_id}")
+
+    timeline_id = str(job.timeline_id) if job.timeline_id else ""
+    if not timeline_id:
+        raise ValueError(f"Job {job_id} has no timeline")
+
+    # Load frames from timeline cache
+    frames = load_cached_frames(timeline_id)
+    if not frames:
+        raise ValueError(f"No cached frames for timeline {timeline_id}. Run the pipeline first.")
+
+    # Load all stage outputs for this job
+    all_outputs = load_stage_outputs_for_job(job_id)
+
+    # Build state with envelope + frames
+    state = {
+        "job_id": job_id,
+        "timeline_id": timeline_id,
+        "video_path": job.video_path,
+        "profile_name": job.profile_name,
+        "source_asset_id": str(job.source_asset_id),
+        "frames": frames,
+        "config_overrides": {},
+    }
+
+    # Apply stage outputs in pipeline order, up to the target stage
+    target_idx = NODES.index(up_to_stage)
+    for stage_name in NODES[:target_idx]:
+        output = all_outputs.get(stage_name)
+        if output:
+            # Stage outputs contain serialized data — merge into state
+            # The stage registry's deserialize_fn can reconstitute if needed
+            for key, value in output.items():
+                state[key] = value
+
+    # Filtered frames: reconstruct from sequence list if present
+    filtered_seqs = state.get("filtered_frame_sequences")
+    if filtered_seqs:
+        seq_set = set(filtered_seqs)
+        state["filtered_frames"] = [f for f in frames if f.sequence in seq_set]
+    elif "filtered_frames" not in state:
+        state["filtered_frames"] = frames
+
+    return state
 
 
 def replay_from(
@@ -38,49 +94,60 @@ def replay_from(
     """
     Replay the pipeline from a specific stage.
 
-    Loads the checkpoint from the stage immediately before start_stage,
-    applies config overrides, and runs the subgraph from start_stage onward.
+    Loads state from the original job's stage outputs up to start_stage,
+    applies config overrides, and runs from start_stage onward.
 
+    Creates a new Job (run_type=REPLAY).
     Returns the final state dict.
     """
     if start_stage not in NODES:
         raise ValueError(f"Unknown stage: {start_stage!r}. Options: {NODES}")
 
     start_idx = NODES.index(start_stage)
-
-    # Load checkpoint from the stage before start_stage
     if start_idx == 0:
         raise ValueError("Cannot replay from the first stage — just run the full pipeline")
 
-    previous_stage = NODES[start_idx - 1]
+    logger.info("Replaying job %s from %s", job_id, start_stage)
 
-    available = list_checkpoints(job_id)
-    if previous_stage not in available:
-        raise ValueError(
-            f"No checkpoint for stage {previous_stage!r} (job {job_id}). "
-            f"Available: {available}"
-        )
-
-    logger.info("Replaying job %s from %s (loading checkpoint: %s)",
-                job_id, start_stage, previous_stage)
-
-    state = load_checkpoint(job_id, previous_stage)
+    state = _build_state_for_replay(job_id, start_stage)
 
     # Apply config overrides
     if config_overrides:
         state["config_overrides"] = config_overrides
 
+    # Create replay job
+    from core.db.connection import get_session
+    from core.db.job import create_job, get_job
+    with get_session() as session:
+        original = get_job(session, uuid.UUID(job_id))
+        replay_job = create_job(
+            session,
+            source_asset_id=original.source_asset_id,
+            video_path=original.video_path,
+            timeline_id=original.timeline_id,
+            profile_name=original.profile_name,
+            run_type="replay",
+            parent_id=original.id,
+            config_overrides=config_overrides,
+        )
+        replay_job_id = str(replay_job.id)
+
+    # Update state with new job ID
+    state["job_id"] = replay_job_id
+
     # Set run context for SSE events
-    run_id = str(uuid.uuid4())[:8]
     emit.set_run_context(
-        run_id=run_id,
+        run_id=replay_job_id,
         parent_job_id=job_id,
         run_type="replay",
     )
 
-    # Build subgraph starting from start_stage
-    graph = build_graph(checkpoint=checkpoint, start_from=start_stage)
-    pipeline = graph.compile()
+    # Run from start_stage onward
+    pipeline = get_pipeline(
+        checkpoint=checkpoint,
+        profile_name=state["profile_name"],
+        start_from=start_stage,
+    )
 
     try:
         result = pipeline.invoke(state)
@@ -102,12 +169,6 @@ def replay_single_stage(
 
     Fast path for interactive parameter tuning — runs only the target stage
     function, not the full pipeline tail. Returns the stage output directly.
-
-    When debug=True and stage is detect_edges, returns additional overlay
-    data (Canny edges, Hough lines) for visual feedback in the editor.
-
-    For detect_edges: returns {"edge_regions_by_frame": {seq: [box, ...]}}
-    With debug=True, also returns {"debug": {seq: {edge_overlay_b64, lines_overlay_b64, ...}}}
     """
     if stage not in NODES:
         raise ValueError(f"Unknown stage: {stage!r}. Options: {NODES}")
@@ -116,19 +177,9 @@ def replay_single_stage(
     if stage_idx == 0:
         raise ValueError("Cannot replay the first stage — just run the full pipeline")
 
-    previous_stage = NODES[stage_idx - 1]
+    logger.info("Single-stage replay: job %s, stage %s (debug=%s)", job_id, stage, debug)
 
-    available = list_checkpoints(job_id)
-    if previous_stage not in available:
-        raise ValueError(
-            f"No checkpoint for stage {previous_stage!r} (job {job_id}). "
-            f"Available: {available}"
-        )
-
-    logger.info("Single-stage replay: job %s, stage %s (loading checkpoint: %s, debug=%s)",
-                job_id, stage, previous_stage, debug)
-
-    state = load_checkpoint(job_id, previous_stage)
+    state = _build_state_for_replay(job_id, stage)
 
     # Build profile with overrides
     from core.detect.profile import get_profile, get_stage_config
@@ -142,9 +193,17 @@ def replay_single_stage(
                 merged_configs[sname] = soverrides
         profile = {**profile, "configs": merged_configs}
 
-    # Run the stage function directly (not through the graph)
+    # Subset frames if requested
+    frames = state.get("filtered_frames", state.get("frames", []))
+    if frame_refs:
+        ref_set = set(frame_refs)
+        frames = [f for f in frames if f.sequence in ref_set]
+
+    # Run the specific stage
     if stage == "detect_edges":
-        return _replay_detect_edges(state, profile, frame_refs, job_id, debug)
+        return _replay_detect_edges(state, profile, frames, job_id, debug)
+    elif stage == "field_segmentation":
+        return _replay_field_segmentation(state, profile, frames, job_id, debug)
     else:
         raise ValueError(
             f"Single-stage replay not yet implemented for {stage!r}. "
@@ -155,35 +214,28 @@ def replay_single_stage(
 def _replay_detect_edges(
     state: dict,
     profile,
-    frame_refs: list[int] | None,
+    frames: list,
     job_id: str,
     debug: bool,
 ) -> dict:
     """Run edge detection on checkpoint frames, optionally with debug overlays."""
-    import os
     from core.detect.stages.edge_detector import detect_edge_regions
-
     from core.detect.profile import get_stage_config
     from core.detect.stages.models import RegionAnalysisConfig
+
     config = RegionAnalysisConfig(**get_stage_config(profile, "detect_edges"))
-    frames = state.get("filtered_frames", [])
-
-    if frame_refs:
-        ref_set = set(frame_refs)
-        frames = [f for f in frames if f.sequence in ref_set]
-
     inference_url = os.environ.get("INFERENCE_URL")
+    field_masks = state.get("field_masks", {})
 
-    # Normal run — always needed for the boxes
     result = detect_edge_regions(
         frames=frames,
         config=config,
         inference_url=inference_url,
         job_id=job_id,
+        field_masks=field_masks,
     )
     output = {"edge_regions_by_frame": result}
 
-    # Debug overlays — call debug endpoint (remote) or local debug function
     if debug and frames:
         debug_data = {}
         if inference_url:
@@ -207,7 +259,6 @@ def _replay_detect_edges(
                     "pair_count": dr.pair_count,
                 }
         else:
-            # Local mode — import GPU module directly
             from core.detect.stages.edge_detector import _load_cv_edges
             edges_mod = _load_cv_edges()
             for frame in frames:
@@ -230,3 +281,27 @@ def _replay_detect_edges(
         output["debug"] = debug_data
 
     return output
+
+
+def _replay_field_segmentation(
+    state: dict,
+    profile,
+    frames: list,
+    job_id: str,
+    debug: bool,
+) -> dict:
+    """Run field segmentation on checkpoint frames."""
+    from core.detect.stages.field_segmentation import run_field_segmentation
+    from core.detect.profile import get_stage_config
+    from core.detect.stages.models import FieldSegmentationConfig
+
+    config = FieldSegmentationConfig(**get_stage_config(profile, "field_segmentation"))
+    inference_url = os.environ.get("INFERENCE_URL")
+
+    result = run_field_segmentation(
+        frames=frames,
+        config=config,
+        inference_url=inference_url,
+        job_id=job_id,
+    )
+    return result
diff --git a/core/detect/checkpoint/runner_bridge.py b/core/detect/checkpoint/runner_bridge.py
index fa69ff6..302097c 100644
--- a/core/detect/checkpoint/runner_bridge.py
+++ b/core/detect/checkpoint/runner_bridge.py
@@ -39,13 +39,21 @@ def checkpoint_after_stage(job_id: str, stage_name: str, state: dict, result: di
         return
 
     from .storage import save_checkpoint, save_stage_output
-    from core.detect.stages.base import _REGISTRY
+    from core.detect.stages.base import _REGISTRY, _LEGACY_REGISTRY
 
     merged = {**state, **result}
 
     # Serialize stage output using the stage's serialize_fn if available
+    # Check new-style registry first, then legacy (some stages are in both)
+    serialize_fn = None
     stage_cls = _REGISTRY.get(stage_name)
-    serialize_fn = getattr(getattr(stage_cls, "definition", None), "serialize_fn", None)
+    if stage_cls:
+        serialize_fn = getattr(getattr(stage_cls, "definition", None), "serialize_fn", None)
+    if not serialize_fn:
+        legacy = _LEGACY_REGISTRY.get(stage_name)
+        if legacy:
+            serialize_fn = legacy.serialize_fn
+
     if serialize_fn:
         output_json = serialize_fn(merged, job_id)
     else:
diff --git a/core/detect/graph/nodes.py b/core/detect/graph/nodes.py
index 25f906d..e70f928 100644
--- a/core/detect/graph/nodes.py
+++ b/core/detect/graph/nodes.py
@@ -146,6 +146,7 @@ def node_field_segmentation(state: DetectState) -> dict:
     _emit(state, "field_segmentation", "done")
     return {
         "field_masks": result["field_masks"],
+        "field_mask_overlays": result.get("field_mask_overlays", {}),
         "field_boundaries": result["field_boundaries"],
         "field_coverage": result["field_coverage"],
     }
diff --git a/core/detect/stages/edge_detector.py b/core/detect/stages/edge_detector.py
index 5755dac..dcc3bcf 100644
--- a/core/detect/stages/edge_detector.py
+++ b/core/detect/stages/edge_detector.py
@@ -24,7 +24,7 @@ from PIL import Image
 from core.detect import emit
 from core.detect.models import BoundingBox, Frame
 from core.detect.stages.base import Stage
-from core.detect.stages.models import StageDefinition, StageConfigField, StageIO
+from core.detect.stages.models import StageDefinition, StageConfigField, StageIO, StageOutputHint
 
 
 logger = logging.getLogger(__name__)
@@ -42,7 +42,6 @@ class EdgeDetectionStage(Stage):
             writes=["edge_regions_by_frame"],
         ),
         config_fields=[
-            StageConfigField(name="enabled", type="bool", default=True, description="Enable edge detection"),
             StageConfigField(name="edge_canny_low", type="int", default=50, description="Canny low threshold", min=0, max=255),
             StageConfigField(name="edge_canny_high", type="int", default=150, description="Canny high threshold", min=0, max=255),
             StageConfigField(name="edge_hough_threshold", type="int", default=80, description="Hough accumulator threshold", min=1, max=500),
@@ -51,6 +50,11 @@ class EdgeDetectionStage(Stage):
             StageConfigField(name="edge_pair_max_distance", type="int", default=200, description="Max distance between line pair (px)", min=10, max=500),
             StageConfigField(name="edge_pair_min_distance", type="int", default=15, description="Min distance between line pair (px)", min=5, max=200),
         ],
+        output_hints=[
+            StageOutputHint(key="edge_regions_by_frame", type="boxes_by_frame", label="Edge regions"),
+            StageOutputHint(key="edge_overlay_b64", type="overlay", label="Canny edges", default_opacity=0.25),
+            StageOutputHint(key="lines_overlay_b64", type="overlay", label="Hough lines", default_opacity=0.25),
+        ],
         tracks_element="edge_region",
     )
 
diff --git a/core/detect/stages/field_segmentation.py b/core/detect/stages/field_segmentation.py
index 953d9d7..cf72b58 100644
--- a/core/detect/stages/field_segmentation.py
+++ b/core/detect/stages/field_segmentation.py
@@ -24,6 +24,7 @@ from core.detect.stages.models import (
     StageConfigField,
     StageDefinition,
     StageIO,
+    StageOutputHint,
 )
 
 logger = logging.getLogger(__name__)
@@ -41,7 +42,6 @@ class FieldSegmentationStage(Stage):
             writes=["field_mask"],
         ),
         config_fields=[
-            StageConfigField(name="enabled", type="bool", default=True, description="Enable field segmentation"),
             StageConfigField(name="hue_low", type="int", default=30, description="HSV hue lower bound", min=0, max=180),
             StageConfigField(name="hue_high", type="int", default=85, description="HSV hue upper bound", min=0, max=180),
             StageConfigField(name="sat_low", type="int", default=30, description="HSV saturation lower bound", min=0, max=255),
@@ -51,6 +51,9 @@ class FieldSegmentationStage(Stage):
             StageConfigField(name="morph_kernel", type="int", default=15, description="Morphology kernel size", min=3, max=51),
             StageConfigField(name="min_area_ratio", type="float", default=0.05, description="Min contour area as fraction of frame", min=0.01, max=0.5),
         ],
+        output_hints=[
+            StageOutputHint(key="mask_overlay_b64", type="overlay", label="Field mask", default_opacity=0.5, src_format="png"),
+        ],
     )
 
 
@@ -102,6 +105,7 @@ def run_field_segmentation(
     client = InferenceClient(base_url=url, job_id=job_id or "", log_level=_run_log_level)
 
     field_masks = {}
+    field_mask_overlays = {}
     field_boundaries = {}
     field_coverage = {}
 
@@ -126,6 +130,7 @@ def run_field_segmentation(
         mask_b64 = resp.get("mask_b64", "")
         if mask_b64:
             field_masks[frame.sequence] = _decode_mask_b64(mask_b64)
+            field_mask_overlays[frame.sequence] = mask_b64
 
         field_boundaries[frame.sequence] = resp.get("boundary", [])
         field_coverage[frame.sequence] = resp.get("coverage", 0.0)
@@ -136,6 +141,7 @@ def run_field_segmentation(
 
     return {
         "field_masks": field_masks,
+        "field_mask_overlays": field_mask_overlays,
         "field_boundaries": field_boundaries,
         "field_coverage": field_coverage,
     }
diff --git a/core/detect/stages/models.py b/core/detect/stages/models.py
index 985b8ce..6225fd9 100644
--- a/core/detect/stages/models.py
+++ b/core/detect/stages/models.py
@@ -27,6 +27,14 @@ class StageIO(BaseModel):
     writes: List[str] = Field(default_factory=list)
     optional_reads: List[str] = Field(default_factory=list)
 
+class StageOutputHint(BaseModel):
+    """How to render a stage output in the compare/editor views."""
+    key: str
+    type: str
+    label: str = ""
+    default_opacity: float = 0.5
+    src_format: str = "png"
+
 class StageDefinition(BaseModel):
     """Complete metadata for a pipeline stage."""
     name: str
@@ -35,6 +43,7 @@ class StageDefinition(BaseModel):
     category: str = "detection"
     io: StageIO
     config_fields: List[StageConfigField] = Field(default_factory=list)
+    output_hints: List[StageOutputHint] = Field(default_factory=list)
     tracks_element: Optional[str] = None
 
 class FrameExtractionConfig(BaseModel):
diff --git a/core/detect/stages/registry/cv_analysis.py b/core/detect/stages/registry/cv_analysis.py
index 10f4645..2cae3d8 100644
--- a/core/detect/stages/registry/cv_analysis.py
+++ b/core/detect/stages/registry/cv_analysis.py
@@ -1,4 +1,4 @@
-"""Registration for CV analysis stages: edge detection."""
+"""Registration for CV analysis stages: edge detection, field segmentation."""
 
 from core.detect.stages.models import StageDefinition, StageIO, StageConfigField
 from core.detect.stages.base import register_stage
@@ -20,6 +20,24 @@ def _deser_regions(data: dict, job_id: str) -> dict:
     return {"edge_regions_by_frame": regions}
 
 
+def _ser_field_seg(state: dict, job_id: str) -> dict:
+    """Serialize field segmentation — boundaries + coverage + mask overlays."""
+    boundaries = state.get("field_boundaries", {})
+    coverage = state.get("field_coverage", {})
+    mask_overlays = state.get("field_mask_overlays", {})
+    return {
+        "field_boundaries": {str(k): v for k, v in boundaries.items()},
+        "field_coverage": {str(k): v for k, v in coverage.items()},
+        "mask_overlays_by_frame": {str(k): v for k, v in mask_overlays.items()},
+    }
+
+
+def _deser_field_seg(data: dict, job_id: str) -> dict:
+    boundaries = {int(k): v for k, v in data.get("field_boundaries", {}).items()}
+    coverage = {int(k): v for k, v in data.get("field_coverage", {}).items()}
+    return {"field_boundaries": boundaries, "field_coverage": coverage}
+
+
 def register():
     edge_detection = StageDefinition(
         name="detect_edges",
@@ -31,7 +49,6 @@ def register():
             writes=["edge_regions_by_frame"],
         ),
         config_fields=[
-            StageConfigField(name="enabled", type="bool", default=True, description="Enable region analysis"),
             StageConfigField(name="edge_canny_low", type="int", default=50, description="Canny low threshold", min=0, max=255),
             StageConfigField(name="edge_canny_high", type="int", default=150, description="Canny high threshold", min=0, max=255),
             StageConfigField(name="edge_hough_threshold", type="int", default=80, description="Hough accumulator threshold", min=1, max=500),
@@ -42,3 +59,25 @@ def register():
         ],
     )
     register_stage(edge_detection, serialize_fn=_ser_regions, deserialize_fn=_deser_regions)
+
+    field_seg = StageDefinition(
+        name="field_segmentation",
+        label="Field Segmentation",
+        description="HSV green mask — detect pitch boundaries",
+        category="cv_analysis",
+        io=StageIO(
+            reads=["filtered_frames"],
+            writes=["field_mask"],
+        ),
+        config_fields=[
+            StageConfigField(name="hue_low", type="int", default=30, description="HSV hue lower bound", min=0, max=180),
+            StageConfigField(name="hue_high", type="int", default=85, description="HSV hue upper bound", min=0, max=180),
+            StageConfigField(name="sat_low", type="int", default=30, description="HSV saturation lower bound", min=0, max=255),
+            StageConfigField(name="sat_high", type="int", default=255, description="HSV saturation upper bound", min=0, max=255),
+            StageConfigField(name="val_low", type="int", default=30, description="HSV value lower bound", min=0, max=255),
+            StageConfigField(name="val_high", type="int", default=255, description="HSV value upper bound", min=0, max=255),
+            StageConfigField(name="morph_kernel", type="int", default=15, description="Morphology kernel size", min=3, max=51),
+            StageConfigField(name="min_area_ratio", type="float", default=0.05, description="Min contour area", min=0.01, max=0.5),
+        ],
+    )
+    register_stage(field_seg, serialize_fn=_ser_field_seg, deserialize_fn=_deser_field_seg)
diff --git a/core/detect/stages/registry/preprocessing.py b/core/detect/stages/registry/preprocessing.py
index 9cd9be0..d69a829 100644
--- a/core/detect/stages/registry/preprocessing.py
+++ b/core/detect/stages/registry/preprocessing.py
@@ -60,7 +60,6 @@ def register():
         io=StageIO(reads=["frames"], writes=["filtered_frames"]),
         config_fields=[
             StageConfigField(name="hamming_threshold", type="int", default=8, description="Hamming distance threshold", min=0, max=64),
-            StageConfigField(name="enabled", type="bool", default=True, description="Enable scene filtering"),
         ],
     )
     register_stage(scene_filter, serialize_fn=_ser_filter, deserialize_fn=_deser_filter)
diff --git a/core/schema/models/stage.py b/core/schema/models/stage.py
index 46f8477..aa99d59 100644
--- a/core/schema/models/stage.py
+++ b/core/schema/models/stage.py
@@ -35,6 +35,16 @@ class StageIO:
     optional_reads: List[str] = field(default_factory=list)
 
 
+@dataclass
+class StageOutputHint:
+    """How to render a stage output in the compare/editor views."""
+    key: str          # key in the stage output JSON, e.g. "edge_regions_by_frame"
+    type: str         # "boxes_by_frame" | "overlay"
+    label: str = ""
+    default_opacity: float = 0.5
+    src_format: str = "png"  # for overlays
+
+
 @dataclass
 class StageDefinition:
     """Complete metadata for a pipeline stage."""
@@ -44,6 +54,7 @@ class StageDefinition:
     category: str = "detection"
     io: StageIO = field(default_factory=StageIO)
     config_fields: List[StageConfigField] = field(default_factory=list)
+    output_hints: List[StageOutputHint] = field(default_factory=list)
     tracks_element: Optional[str] = None
 
 
@@ -139,6 +150,7 @@ class PipelineConfig:
 STAGE_VIEWS = [
     StageConfigField,
     StageIO,
+    StageOutputHint,
     StageDefinition,
     FrameExtractionConfig,
     SceneFilterConfig,
diff --git a/tests/detect/manual/seed_scenario.py b/tests/detect/manual/seed_scenario.py
index d97dbfe..759774a 100644
--- a/tests/detect/manual/seed_scenario.py
+++ b/tests/detect/manual/seed_scenario.py
@@ -2,8 +2,8 @@
 """
 Seed a scenario from a video chunk.
 
-Creates a Timeline (frames in MinIO) + Branch + Checkpoint marked
-as a scenario. No pipeline, no Redis, no SSE.
+Creates a Timeline + caches frames + Checkpoint marked as scenario.
+No pipeline, no Redis, no SSE.
 
 Prerequisites:
   - Postgres reachable (Kind NodePort or local)
@@ -14,7 +14,7 @@ Usage:
     python tests/detect/manual/seed_scenario.py --video media/mpr/out/chunks/.../chunk_0001.mp4
 
 Then open:
-    http://mpr.local.ar/detection/?job=<TIMELINE_ID>#/editor/detect_edges
+    http://mpr.local.ar/detection/?job=<JOB_ID>#/editor/detect_edges
 """
 
 from __future__ import annotations
@@ -110,36 +110,41 @@ def main():
     frames = extract_frames_ffmpeg(video_path, args.fps, args.max_frames)
     logger.info("Extracted %d frames", len(frames))
 
-    # Create timeline + branch + checkpoint
-    from core.detect.checkpoint.storage import create_timeline, save_stage_output
+    # Create timeline
+    from core.detect.checkpoint.storage import (
+        create_timeline, save_checkpoint, update_timeline_status,
+    )
+    from core.detect.checkpoint.frames import cache_frames
 
-    timeline_id, branch_id = create_timeline(
-        source_video=video_path,
+    timeline_id = create_timeline(
+        chunk_paths=[video_path],
         profile_name="soccer_broadcast",
-        frames=frames,
+        name=args.label,
         fps=args.fps,
     )
 
-    # Mark as scenario
-    from core.db import get_latest_checkpoint
-    from core.db.connection import get_session
+    # Cache frames on the timeline
+    cache_frames(timeline_id, frames)
+    update_timeline_status(timeline_id, "cached", frame_count=len(frames))
 
-    with get_session() as session:
-        checkpoint = get_latest_checkpoint(session, branch_id)
-        if checkpoint:
-            checkpoint.is_scenario = True
-            checkpoint.scenario_label = args.label
-            session.commit()
+    # Create scenario checkpoint
+    checkpoint_id = save_checkpoint(
+        timeline_id=timeline_id,
+        stage_name="extract_frames",
+        is_scenario=True,
+        scenario_label=args.label,
+        stats={"frames_extracted": len(frames)},
+    )
 
     logger.info("")
     logger.info("Scenario created:")
     logger.info("  Timeline: %s", timeline_id)
-    logger.info("  Branch: %s", branch_id)
+    logger.info("  Checkpoint: %s", checkpoint_id)
     logger.info("  Label: %s", args.label)
     logger.info("  Frames: %d", len(frames))
     logger.info("")
-    logger.info("Open in editor:")
-    logger.info("  http://mpr.local.ar/detection/?job=%s#/editor/detect_edges", timeline_id)
+    logger.info("Open in source selector to see the timeline:")
+    logger.info("  http://mpr.local.ar/detection/")
 
 
 if __name__ == "__main__":
diff --git a/ui/detection-app/src/App.vue b/ui/detection-app/src/App.vue
index 31ada30..6dc6eb5 100644
--- a/ui/detection-app/src/App.vue
+++ b/ui/detection-app/src/App.vue
@@ -10,7 +10,9 @@ import BrandTablePanel from './panels/BrandTablePanel.vue'
 import TimelinePanel from './panels/TimelinePanel.vue'
 import CostStatsPanel from './panels/CostStatsPanel.vue'
 import SourceSelector from './panels/SourceSelector.vue'
+import CompareView from './panels/CompareView.vue'
 import StageConfig from './components/StageConfig.vue'
+import OverlayControls from './components/OverlayControls.vue'
 import FrameStrip from './components/FrameStrip.vue'
 import { usePipelineStore } from './stores/pipeline'
 import { useSSEConnection } from './composables/useSSEConnection'
@@ -41,9 +43,14 @@ const {
 // Editor overlays + CV result accumulation
 const {
   editorOverlays, editorBoxes,
-  updateDisplayForFrame, onReplayResult, setActiveStage,
+  updateDisplayForFrame, onReplayResult: _onReplayResult, setActiveStage,
+  saveOverlaysToCache,
 } = useEditorState(currentFrameRef)
 
+function onReplayResult(result: any) {
+  _onReplayResult(result)
+}
+
 // Set active stage when editor opens
 watch(() => pipeline.editorStage, (stage) => {
   if (stage) setActiveStage(stage)
@@ -56,6 +63,13 @@ function setCheckpointFrame(index: number) {
   if (frame) updateDisplayForFrame(frame.seq)
 }
 
+// Save overlays to S3 cache then close editor
+function closeEditorWithSave() {
+  saveOverlaysToCache(pipeline.timelineId, pipeline.jobId)
+  // Small delay to let the save requests fire before navigation
+  setTimeout(() => pipeline.closeEditor(), 100)
+}
+
 // Wire job start to clear log panel
 function onJobStarted(newJobId: string, opts?: { pauseAfterStage?: boolean }) {
   logPanel.value?.clear()
@@ -74,6 +88,11 @@ function onJobStarted(newJobId: string, opts?: { pauseAfterStage?: boolean }) {
           <path d="M2 4h4l2 2h6v8H2V4z"/><path d="M2 4V2h12v2"/>
         </svg>
       </button>
+      <button class="header-btn" title="Compare jobs" @click="pipeline.openCompare()">
+        <svg width="14" height="14" viewBox="0 0 16 16" fill="none" stroke="currentColor" stroke-width="1.5">
+          <rect x="1" y="3" width="6" height="10" rx="1"/><rect x="9" y="3" width="6" height="10" rx="1"/><path d="M8 5v6"/>
+        </svg>
+      </button>
 
       <!-- Transport controls — visible when a pipeline is running -->
       <div v-if="sseConnected && (status === 'live' || status === 'processing' || paused)" class="transport">
@@ -210,21 +229,8 @@ function onJobStarted(newJobId: string, opts?: { pauseAfterStage?: boolean }) {
           />
 
           <div class="editor-bottom">
-            <div class="overlay-controls">
-              <label v-for="(overlay, idx) in editorOverlays" :key="idx" class="overlay-toggle">
-                <input type="checkbox" v-model="overlay.visible" />
-                <span class="overlay-label">{{ overlay.label }}</span>
-                <input
-                  type="range"
-                  min="0" max="1" step="0.05"
-                  :value="overlay.opacity ?? 0.5"
-                  @input="(e: Event) => overlay.opacity = Number((e.target as HTMLInputElement).value)"
-                  class="opacity-slider"
-                />
-                <span class="opacity-value">{{ Math.round((overlay.opacity ?? 0.5) * 100) }}%</span>
-              </label>
-            </div>
-            <button class="editor-close" @click="pipeline.closeEditor()">✕ Close</button>
+            <OverlayControls :overlays="editorOverlays" />
+            <button class="editor-close" @click="closeEditorWithSave()">✕ Close</button>
           </div>
         </div>
 
@@ -242,6 +248,9 @@ function onJobStarted(newJobId: string, opts?: { pauseAfterStage?: boolean }) {
         <!-- === SOURCE SELECTOR MODE === -->
         <SourceSelector v-else-if="pipeline.layoutMode === 'source_selector'" @job-started="(id: string, opts: any) => onJobStarted(id, opts)" />
 
+        <!-- === COMPARE MODE === -->
+        <CompareView v-else-if="pipeline.layoutMode === 'compare'" />
+
       </template>
     </SplitPane>
 
@@ -457,41 +466,6 @@ header h1 { font-size: var(--font-size-lg); font-weight: 600; }
   font-size: var(--font-size-sm);
 }
 
-.overlay-controls {
-  display: flex;
-  gap: var(--space-4);
-  padding: var(--space-2) var(--space-3);
-  align-items: center;
-  height: 100%;
-}
-
-.overlay-toggle {
-  display: flex;
-  align-items: center;
-  gap: var(--space-2);
-  font-size: var(--font-size-sm);
-  color: var(--text-secondary);
-  cursor: pointer;
-}
-
-.overlay-toggle input[type="checkbox"] {
-  accent-color: #00bcd4;
-}
-
-.overlay-label {
-  min-width: 80px;
-}
-
-.opacity-slider {
-  width: 80px;
-  height: 3px;
-}
-
-.opacity-value {
-  font-size: 10px;
-  color: var(--text-dim);
-  min-width: 30px;
-}
 
 /* Source selector */
 .source-selector {
diff --git a/ui/detection-app/src/components/OverlayControls.vue b/ui/detection-app/src/components/OverlayControls.vue
new file mode 100644
index 0000000..1a7ece5
--- /dev/null
+++ b/ui/detection-app/src/components/OverlayControls.vue
@@ -0,0 +1,62 @@
+<script setup lang="ts">
+import type { FrameOverlay } from 'mpr-ui-framework'
+
+defineProps<{
+  overlays: FrameOverlay[]
+}>()
+</script>
+
+<template>
+  <div class="overlay-controls">
+    <label v-for="(overlay, idx) in overlays" :key="idx" class="overlay-toggle">
+      <input type="checkbox" v-model="overlay.visible" />
+      <span class="overlay-label">{{ overlay.label }}</span>
+      <input
+        type="range"
+        min="0" max="1" step="0.05"
+        :value="overlay.opacity ?? 0.5"
+        @input="(e: Event) => overlay.opacity = Number((e.target as HTMLInputElement).value)"
+        class="opacity-slider"
+      />
+      <span class="opacity-value">{{ Math.round((overlay.opacity ?? 0.5) * 100) }}%</span>
+    </label>
+  </div>
+</template>
+
+<style scoped>
+.overlay-controls {
+  display: flex;
+  gap: var(--space-4);
+  padding: var(--space-2) var(--space-3);
+  align-items: center;
+  height: 100%;
+}
+
+.overlay-toggle {
+  display: flex;
+  align-items: center;
+  gap: var(--space-2);
+  font-size: var(--font-size-sm);
+  color: var(--text-secondary);
+  cursor: pointer;
+}
+
+.overlay-toggle input[type="checkbox"] {
+  accent-color: #00bcd4;
+}
+
+.overlay-label {
+  min-width: 50px;
+}
+
+.opacity-slider {
+  width: 80px;
+  height: 3px;
+}
+
+.opacity-value {
+  font-size: 10px;
+  color: var(--text-dim);
+  min-width: 30px;
+}
+</style>
diff --git a/ui/detection-app/src/composables/useCheckpointLoader.ts b/ui/detection-app/src/composables/useCheckpointLoader.ts
index aad131d..e967360 100644
--- a/ui/detection-app/src/composables/useCheckpointLoader.ts
+++ b/ui/detection-app/src/composables/useCheckpointLoader.ts
@@ -71,10 +71,11 @@ export function useCheckpointLoader(
   const { stages, checkpointStageFor } = useStageRegistry()
 
   // Auto-load checkpoint when entering editor mode.
+  // Also watches timelineId — it resolves async on page load.
   watch(
-    () => [pipeline.layoutMode, pipeline.editorStage, jobId.value, stages.value.length] as const,
+    () => [pipeline.layoutMode, pipeline.editorStage, jobId.value, stages.value.length, pipeline.timelineId] as const,
     ([mode, stage, job]) => {
-      if (mode === 'bbox_editor' && stage && job) {
+      if (mode === 'bbox_editor' && stage && job && pipeline.timelineId) {
         const cpStage = checkpointStageFor(stage)
         if (cpStage) {
           loadCheckpoint(job, cpStage)
diff --git a/ui/detection-app/src/composables/useEditorState.ts b/ui/detection-app/src/composables/useEditorState.ts
index 125d3c6..5b4c0b8 100644
--- a/ui/detection-app/src/composables/useEditorState.ts
+++ b/ui/detection-app/src/composables/useEditorState.ts
@@ -69,7 +69,7 @@ export function useEditorState(currentFrameRef: Ref<number | null>) {
     }
   }
 
-  function onReplayResult(result: StageResult) {
+  function onReplayResult(result: StageResult, jobId?: string) {
     if (result.frameWidth && result.frameHeight) {
       frameDimensions.value = { w: result.frameWidth, h: result.frameHeight }
     }
@@ -115,6 +115,28 @@ export function useEditorState(currentFrameRef: Ref<number | null>) {
     }))
   }
 
+  async function saveOverlaysToCache(timelineId: string, jobId: string) {
+    const stage = activeStage.value
+    if (!stage) return
+
+    const entries = Object.entries(allFrameOverlays.value)
+    if (entries.length === 0) return
+
+    for (const [seqStr, overlayMap] of entries) {
+      fetch('/api/detect/overlays', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          timeline_id: timelineId,
+          job_id: jobId,
+          stage,
+          seq: Number(seqStr),
+          overlays: overlayMap,
+        }),
+      }).catch(() => {})
+    }
+  }
+
   function resetEditorState() {
     activeStage.value = null
     allFrameRegions.value = {}
@@ -136,6 +158,7 @@ export function useEditorState(currentFrameRef: Ref<number | null>) {
     updateDisplayForFrame,
     onReplayResult,
     setActiveStage,
+    saveOverlaysToCache,
     resetEditorState,
   }
 }
diff --git a/ui/detection-app/src/composables/useHashRouter.ts b/ui/detection-app/src/composables/useHashRouter.ts
index 12b64e4..d87dfc8 100644
--- a/ui/detection-app/src/composables/useHashRouter.ts
+++ b/ui/detection-app/src/composables/useHashRouter.ts
@@ -32,6 +32,9 @@ export function useHashRouter() {
     if (configMatch) {
       return { mode: 'stage_editor', stage: configMatch[1] }
     }
+    if (path === 'compare') {
+      return { mode: 'compare', stage: null as string | null }
+    }
     return { mode: 'normal', stage: null as string | null }
   }
 
@@ -49,6 +52,8 @@ export function useHashRouter() {
       hash = `#/config/${pipeline.editorStage}`
     } else if (pipeline.layoutMode === 'source_selector') {
       hash = '#/source'
+    } else if (pipeline.layoutMode === 'compare') {
+      hash = '#/compare'
     }
     if (window.location.hash !== hash) {
       window.history.pushState(null, '', hash)
diff --git a/ui/detection-app/src/composables/useSSEConnection.ts b/ui/detection-app/src/composables/useSSEConnection.ts
index b845a15..cf1e776 100644
--- a/ui/detection-app/src/composables/useSSEConnection.ts
+++ b/ui/detection-app/src/composables/useSSEConnection.ts
@@ -28,6 +28,19 @@ export function useSSEConnection() {
     pipeline.openSourceSelector()
   }
 
+  // Resolve timeline_id from job on init
+  if (jobParam) {
+    pipeline.setJob(jobParam)
+    fetch(`/api/detect/jobs/${jobParam}`)
+      .then(r => r.ok ? r.json() : null)
+      .then(data => {
+        if (data?.timeline_id) {
+          pipeline.setTimelineId(data.timeline_id)
+        }
+      })
+      .catch(() => {})
+  }
+
   const source = new SSEDataSource({
     id: 'detect-stream',
     url: jobId.value ? `/api/detect/stream/${jobId.value}` : '',
diff --git a/ui/detection-app/src/composables/useStageRegistry.ts b/ui/detection-app/src/composables/useStageRegistry.ts
index 0e5f53a..8ffe353 100644
--- a/ui/detection-app/src/composables/useStageRegistry.ts
+++ b/ui/detection-app/src/composables/useStageRegistry.ts
@@ -11,12 +11,21 @@ export interface StageConfigField {
   options: string[] | null
 }
 
+export interface StageOutputHint {
+  key: string
+  type: string  // "boxes_by_frame" | "overlay"
+  label: string
+  default_opacity: number
+  src_format: string
+}
+
 export interface StageInfo {
   name: string
   label: string
   description: string
   category: string
   config_fields: StageConfigField[]
+  output_hints: StageOutputHint[]
   reads: string[]
   writes: string[]
 }
diff --git a/ui/detection-app/src/panels/CompareView.vue b/ui/detection-app/src/panels/CompareView.vue
new file mode 100644
index 0000000..244c0fd
--- /dev/null
+++ b/ui/detection-app/src/panels/CompareView.vue
@@ -0,0 +1,573 @@
+<script setup lang="ts">
+import { ref, computed, watch, onMounted } from 'vue'
+import { Panel, SplitPane, FrameRenderer } from 'mpr-ui-framework'
+import type { FrameBBox, FrameOverlay } from 'mpr-ui-framework'
+import type { Job, Checkpoint } from '@common/types/generated'
+import { usePipelineStore } from '../stores/pipeline'
+import { useStageRegistry } from '../composables/useStageRegistry'
+import type { StageOutputHint } from '../composables/useStageRegistry'
+import FrameStrip from '../components/FrameStrip.vue'
+import OverlayControls from '../components/OverlayControls.vue'
+import { getOverlays } from '../composables/useOverlayCache'
+
+const pipeline = usePipelineStore()
+const { editableStages, getStage } = useStageRegistry()
+
+function isEditable(stage: string): boolean {
+  return editableStages.value.includes(stage)
+}
+
+function openEditor(jobId: string, stage: string) {
+  // Navigate to editor for this job + stage
+  const url = new URL(window.location.href)
+  url.searchParams.set('job', jobId)
+  url.hash = `#/editor/${stage}`
+  window.location.href = url.toString()
+}
+
+interface JobDetail {
+  id: string
+  timeline_id: string | null
+  profile_name: string
+  status: string
+  config_overrides: Record<string, unknown>
+  checkpoints: { stage_name: string; stats: Record<string, unknown> }[]
+  stage_outputs: Record<string, Record<string, unknown>>
+}
+
+interface CheckpointFrame {
+  seq: number
+  timestamp: number
+  jpeg_b64: string
+}
+
+// Two sides
+const jobA = ref<JobDetail | null>(null)
+const jobB = ref<JobDetail | null>(null)
+
+// Available jobs for this timeline
+const jobs = ref<Job[]>([])
+
+// Shared frames from timeline cache
+const frames = ref<CheckpointFrame[]>([])
+const frameIndex = ref(0)
+
+// Only show stages that have visual editors
+const stages = computed(() => {
+  if (!jobA.value) return []
+  const editable = new Set(editableStages.value)
+  return jobA.value.checkpoints
+    .filter(c => c.stage_name && editable.has(c.stage_name))
+    .map(c => c.stage_name)
+})
+
+// Persist selections in localStorage
+const STORAGE_KEY = 'mpr:compare'
+
+function loadSaved(): { jobA?: string; jobB?: string; stage?: string } {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY)
+    return raw ? JSON.parse(raw) : {}
+  } catch { return {} }
+}
+
+function saveSelection() {
+  const data = {
+    jobA: jobA.value?.id ?? '',
+    jobB: jobB.value?.id ?? '',
+    stage: selectedStage.value,
+  }
+  localStorage.setItem(STORAGE_KEY, JSON.stringify(data))
+}
+
+const saved = loadSaved()
+const selectedStage = ref(saved.stage ?? '')
+
+// Current frame image
+const currentFrame = computed(() => frames.value[frameIndex.value] ?? null)
+const currentImage = computed(() => currentFrame.value?.jpeg_b64 ?? '')
+const currentSeq = computed(() => currentFrame.value?.seq ?? 0)
+
+// Generic box extraction from stage outputs using output_hints
+function boxesForJob(job: JobDetail | null): FrameBBox[] {
+  if (!job || !selectedStage.value) return []
+  const output = job.stage_outputs[selectedStage.value]
+  if (!output) return []
+
+  const stage = getStage(selectedStage.value)
+  if (!stage) return []
+
+  const boxHints = stage.output_hints.filter(h => h.type === 'boxes_by_frame')
+  const allBoxes: FrameBBox[] = []
+
+  for (const hint of boxHints) {
+    const regions = output[hint.key] as Record<string, unknown[]> | undefined
+    if (!regions) continue
+
+    const seq = String(currentSeq.value)
+    const boxes = regions[seq] as { x: number; y: number; w: number; h: number; confidence: number; label: string }[] | undefined
+    if (boxes) {
+      for (const b of boxes) {
+        allBoxes.push({
+          x: b.x, y: b.y, w: b.w, h: b.h,
+          confidence: b.confidence,
+          label: b.label || '',
+        })
+      }
+    }
+  }
+
+  return allBoxes
+}
+
+const boxesA = computed(() => boxesForJob(jobA.value))
+const boxesB = computed(() => boxesForJob(jobB.value))
+
+
+// Debug overlays from S3 cache — driven by stage registry output_hints
+const overlaysA = ref<FrameOverlay[]>([])
+const overlaysB = ref<FrameOverlay[]>([])
+
+function overlayHintsForStage(): StageOutputHint[] {
+  const stage = getStage(selectedStage.value)
+  if (!stage) return []
+  return stage.output_hints.filter(h => h.type === 'overlay')
+}
+
+async function loadOverlaysForFrame(
+  job: JobDetail | null,
+  seq: number,
+  target: typeof overlaysA,
+) {
+  if (!job || !selectedStage.value || !pipeline.timelineId) {
+    target.value = []
+    return
+  }
+
+  const hints = overlayHintsForStage()
+  if (hints.length === 0) {
+    target.value = []
+    return
+  }
+
+  // First check stage outputs for inline overlay data (e.g. mask_overlays_by_frame)
+  const stageOutput = job.stage_outputs[selectedStage.value] ?? {}
+  const prev = new Map(target.value.map(o => [o.label, o]))
+
+  // Try inline overlays from stage output (keyed by frame seq)
+  let foundInline = false
+  const result: FrameOverlay[] = []
+  for (const h of hints) {
+    const existing = prev.get(h.label)
+    // Convention: overlay data in stage output uses key with _by_frame suffix
+    const byFrameKey = h.key.replace('_b64', 's_by_frame').replace('overlay', 'overlay')
+    // Try common patterns: mask_overlays_by_frame, etc.
+    const possibleKeys = [
+      `${h.key.replace('_b64', '')}_by_frame`,
+      `${h.key.replace('_b64', 's')}_by_frame`,
+      `mask_overlays_by_frame`,
+    ]
+    let src = ''
+    for (const k of possibleKeys) {
+      const byFrame = stageOutput[k] as Record<string, string> | undefined
+      if (byFrame && byFrame[String(seq)]) {
+        src = byFrame[String(seq)]
+        foundInline = true
+        break
+      }
+    }
+    result.push({
+      src,
+      label: h.label,
+      visible: existing?.visible ?? true,
+      opacity: existing?.opacity ?? h.default_opacity,
+      srcFormat: h.src_format as 'jpeg' | 'png',
+    })
+  }
+
+  if (foundInline) {
+    target.value = result
+    return
+  }
+
+  // Fall back to S3 overlay cache
+  try {
+    const resp = await fetch(
+      `/api/detect/overlays/${pipeline.timelineId}/${job.id}/${selectedStage.value}/${seq}`
+    )
+    const data = resp.ok ? await resp.json() : {}
+    const cached = data.overlays ?? {}
+
+    target.value = hints.map(h => {
+      const existing = prev.get(h.label)
+      return {
+        src: cached[h.key] ?? '',
+        label: h.label,
+        visible: existing?.visible ?? true,
+        opacity: existing?.opacity ?? h.default_opacity,
+        srcFormat: h.src_format as 'jpeg' | 'png',
+      }
+    })
+  } catch {
+    target.value = result  // use whatever we have (possibly empty)
+  }
+}
+
+// Reload overlays when frame or stage changes
+function refreshOverlays() {
+  loadOverlaysForFrame(jobA.value, currentSeq.value, overlaysA)
+  loadOverlaysForFrame(jobB.value, currentSeq.value, overlaysB)
+}
+
+watch([currentSeq, selectedStage], refreshOverlays)
+
+// Sync overlay visibility/opacity from A controls → B overlays
+watch(overlaysA, (aList) => {
+  for (const a of aList) {
+    const b = overlaysB.value.find(o => o.label === a.label)
+    if (b) {
+      b.visible = a.visible
+      b.opacity = a.opacity
+    }
+  }
+}, { deep: true })
+
+// Resolve timeline from a saved job if store doesn't have it
+async function ensureTimelineId(): Promise<string> {
+  if (pipeline.timelineId) return pipeline.timelineId
+
+  // Try to resolve from saved job selection
+  const savedJobId = saved.jobA || saved.jobB
+  if (savedJobId) {
+    try {
+      const resp = await fetch(`/api/detect/jobs/${savedJobId}`)
+      if (resp.ok) {
+        const data = await resp.json()
+        if (data.timeline_id) {
+          pipeline.setTimelineId(data.timeline_id)
+          return data.timeline_id
+        }
+      }
+    } catch { /* ignore */ }
+  }
+  return ''
+}
+
+// Load jobs — prefer current timeline, fall back to all jobs
+async function loadJobs() {
+  const tid = await ensureTimelineId()
+  const url = tid
+    ? `/api/detect/jobs?timeline_id=${tid}`
+    : '/api/detect/jobs'
+  try {
+    const resp = await fetch(url)
+    if (!resp.ok) return
+    const result = await resp.json()
+    // If only one job on this timeline, show all jobs for comparison
+    if (tid && result.length < 2) {
+      const allResp = await fetch('/api/detect/jobs')
+      if (allResp.ok) {
+        jobs.value = await allResp.json()
+        return
+      }
+    }
+    jobs.value = result
+  } catch { /* ignore */ }
+}
+
+// Load a job's detail
+async function loadJobDetail(jobId: string): Promise<JobDetail | null> {
+  try {
+    const resp = await fetch(`/api/detect/jobs/${jobId}`)
+    if (!resp.ok) return null
+    return await resp.json()
+  } catch {
+    return null
+  }
+}
+
+// Load frames from timeline cache via checkpoint endpoint
+async function loadFrames(stage: string) {
+  const tid = pipeline.timelineId
+  if (!tid) return
+  try {
+    const resp = await fetch(`/api/detect/checkpoints/${tid}/${stage}`)
+    if (!resp.ok) return
+    const data = await resp.json()
+    frames.value = data.frames ?? []
+    frameIndex.value = 0
+  } catch { /* ignore */ }
+}
+
+async function selectJobA(job: Job) {
+  jobA.value = await loadJobDetail(job.id)
+  if (jobA.value && stages.value.length > 0 && !selectedStage.value) {
+    selectedStage.value = stages.value[0]
+  }
+  // Load frames if stage is already selected (e.g. restored from localStorage)
+  if (selectedStage.value && frames.value.length === 0) {
+    await loadFrames(selectedStage.value)
+  }
+  refreshOverlays()
+  saveSelection()
+}
+
+async function selectJobB(job: Job) {
+  jobB.value = await loadJobDetail(job.id)
+  refreshOverlays()
+  saveSelection()
+}
+
+function jobLabel(j: Job): string {
+  const id = j.id.slice(0, 8)
+  const date = j.created_at ? new Date(j.created_at).toLocaleTimeString(undefined, { hour: '2-digit', minute: '2-digit' }) : ''
+  const overrides = Object.keys(j.config_overrides || {}).length
+  const extra = overrides ? ` +${overrides} overrides` : ''
+  return `${id} ${j.run_type} ${j.status} ${date}${extra}`
+}
+
+function setFrame(index: number) {
+  if (index >= 0 && index < frames.value.length) {
+    frameIndex.value = index
+  }
+}
+
+// Load frames when stage selection changes
+watch(selectedStage, (stage) => {
+  if (stage) {
+    loadFrames(stage)
+    saveSelection()
+  }
+})
+
+// Auto-select last two jobs (most recent first in the list)
+watch(jobs, (list) => {
+  if (list.length === 0) return
+
+  if (list.length >= 2 && !jobA.value) selectJobA(list[0])
+  if (list.length >= 2 && !jobB.value) selectJobB(list[1])
+  else if (list.length === 1 && !jobA.value) selectJobA(list[0])
+}, { immediate: true })
+
+// Load on mount, and also when timelineId becomes available (async from SSE init)
+onMounted(loadJobs)
+watch(() => pipeline.timelineId, (tid) => {
+  if (tid && jobs.value.length === 0) loadJobs()
+})
+</script>
+
+<template>
+  <div class="compare-view">
+    <!-- Header: job selectors + stage selector -->
+    <div class="compare-header">
+      <div class="job-selector">
+        <label>A</label>
+        <select @change="(e: Event) => { const id = (e.target as HTMLSelectElement).value; const j = jobs.find(j => j.id === id); if (j) selectJobA(j) }">
+          <option value="">select job...</option>
+          <option v-for="j in jobs" :key="j.id" :value="j.id" :selected="jobA?.id === j.id">
+            {{ jobLabel(j) }}
+          </option>
+        </select>
+      </div>
+
+      <div class="stage-selector">
+        <select v-model="selectedStage">
+          <option v-for="s in stages" :key="s" :value="s">{{ s.replace(/_/g, ' ') }}</option>
+        </select>
+      </div>
+
+      <div class="job-selector">
+        <label>B</label>
+        <select @change="(e: Event) => { const id = (e.target as HTMLSelectElement).value; const j = jobs.find(j => j.id === id); if (j) selectJobB(j) }">
+          <option value="">select job...</option>
+          <option v-for="j in jobs" :key="j.id" :value="j.id" :selected="jobB?.id === j.id">
+            {{ jobLabel(j) }}
+          </option>
+        </select>
+      </div>
+
+      <button class="close-btn" @click="pipeline.closeEditor()">Close</button>
+    </div>
+
+    <!-- Two frame panels side by side -->
+    <div class="compare-frames">
+      <SplitPane direction="horizontal" :initial-size="1" size-mode="ratio" :min="0.3" :max="3">
+        <template #first>
+          <Panel :title="jobA ? `A: ${jobA.id.slice(0, 8)}` : 'A'" status="idle">
+            <div class="compare-frame-content">
+              <FrameRenderer :image-src="currentImage" :boxes="boxesA" :overlays="overlaysA" />
+              <button
+                v-if="jobA && selectedStage && isEditable(selectedStage)"
+                class="edit-btn"
+                title="Edit this stage"
+                @click="openEditor(jobA.id, selectedStage)"
+              >
+                <svg width="14" height="14" viewBox="0 0 12 12" fill="none" stroke="currentColor" stroke-width="1.5">
+                  <circle cx="5" cy="5" r="3.5"/><line x1="7.5" y1="7.5" x2="11" y2="11"/>
+                </svg>
+              </button>
+            </div>
+          </Panel>
+        </template>
+        <template #second>
+          <Panel :title="jobB ? `B: ${jobB.id.slice(0, 8)}` : 'B'" status="idle">
+            <div class="compare-frame-content">
+              <FrameRenderer :image-src="currentImage" :boxes="boxesB" :overlays="overlaysB" />
+              <button
+                v-if="jobB && selectedStage && isEditable(selectedStage)"
+                class="edit-btn"
+                title="Edit this stage"
+                @click="openEditor(jobB.id, selectedStage)"
+              >
+                <svg width="14" height="14" viewBox="0 0 12 12" fill="none" stroke="currentColor" stroke-width="1.5">
+                  <circle cx="5" cy="5" r="3.5"/><line x1="7.5" y1="7.5" x2="11" y2="11"/>
+                </svg>
+              </button>
+            </div>
+          </Panel>
+        </template>
+      </SplitPane>
+    </div>
+
+    <!-- Shared frame strip -->
+    <FrameStrip
+      v-if="frames.length > 0"
+      :frames="frames"
+      :current-index="frameIndex"
+      :selection-start="0"
+      :selection-end="frames.length - 1"
+      @frame-click="setFrame"
+    />
+
+    <!-- Overlay controls + stats -->
+    <div class="compare-bottom">
+      <OverlayControls :overlays="overlaysA" />
+      <div class="compare-stats" v-if="selectedStage">
+        <span class="stat-side">A: <strong>{{ boxesA.length }}</strong></span>
+        <span class="stat-side">B: <strong>{{ boxesB.length }}</strong></span>
+      </div>
+    </div>
+  </div>
+</template>
+
+<style scoped>
+.compare-view {
+  display: flex;
+  flex-direction: column;
+  height: 100%;
+  min-height: 0;
+  overflow: hidden;
+}
+
+.compare-header {
+  display: flex;
+  align-items: center;
+  gap: var(--space-3);
+  padding: var(--space-2) var(--space-3);
+  background: var(--surface-2);
+  border-bottom: var(--panel-border);
+  flex-shrink: 0;
+}
+
+.job-selector {
+  display: flex;
+  align-items: center;
+  gap: var(--space-2);
+}
+
+.job-selector label {
+  font-weight: 700;
+  font-size: var(--font-size-sm);
+  color: var(--text-secondary);
+  min-width: 14px;
+}
+
+.job-selector select,
+.stage-selector select {
+  background: var(--surface-1);
+  border: 1px solid var(--surface-3);
+  border-radius: 3px;
+  color: var(--text-secondary);
+  font-family: var(--font-mono);
+  font-size: var(--font-size-sm);
+  padding: 3px 6px;
+}
+
+.stage-selector {
+  margin: 0 auto;
+}
+
+.close-btn {
+  background: var(--surface-3);
+  border: 1px solid var(--surface-3);
+  border-radius: 4px;
+  padding: 3px 10px;
+  color: var(--text-secondary);
+  font-family: var(--font-mono);
+  font-size: var(--font-size-sm);
+  cursor: pointer;
+  margin-left: auto;
+}
+
+.close-btn:hover {
+  background: var(--status-error);
+  color: #000;
+}
+
+.compare-frames {
+  flex: 1;
+  min-height: 0;
+  overflow: hidden;
+}
+
+.compare-frame-content {
+  height: 100%;
+  min-height: 0;
+}
+
+.compare-bottom {
+  display: flex;
+  align-items: center;
+  gap: var(--space-4);
+  padding: var(--space-2) var(--space-3);
+  background: var(--surface-2);
+  border-top: var(--panel-border);
+  flex-shrink: 0;
+  height: 36px;
+}
+
+.compare-stats {
+  display: flex;
+  gap: var(--space-4);
+  font-size: var(--font-size-sm);
+  color: var(--text-dim);
+  margin-left: auto;
+}
+
+.compare-frame-content {
+  position: relative;
+}
+
+.edit-btn {
+  position: absolute;
+  top: 8px;
+  right: 8px;
+  background: rgba(0, 0, 0, 0.5);
+  border: 1px solid var(--surface-3);
+  border-radius: 4px;
+  width: 28px;
+  height: 28px;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: var(--text-secondary);
+  transition: all 0.15s;
+  z-index: 1;
+}
+
+.edit-btn:hover {
+  background: rgba(0, 0, 0, 0.7);
+  color: var(--text-primary);
+}
+</style>
diff --git a/ui/detection-app/src/panels/SourceSelector.vue b/ui/detection-app/src/panels/SourceSelector.vue
index d4e0971..a0508e6 100644
--- a/ui/detection-app/src/panels/SourceSelector.vue
+++ b/ui/detection-app/src/panels/SourceSelector.vue
@@ -210,6 +210,36 @@ async function runPipeline() {
   }
 }
 
+async function runOnTimeline(timelineId: string) {
+  running.value = true
+  error.value = null
+  try {
+    const resp = await fetch('/api/detect/run', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        timeline_id: timelineId,
+        profile_name: selectedProfile.value,
+        checkpoint: checkpoint.value,
+        skip_vlm: skipVlm.value,
+        skip_cloud: skipCloud.value,
+        log_level: logLevel.value,
+        pause_after_stage: pauseAfterStage.value,
+      }),
+    })
+    if (!resp.ok) {
+      const detail = await resp.text()
+      throw new Error(`${resp.status}: ${detail}`)
+    }
+    const data = await resp.json()
+    pipeline.setTimelineId(timelineId)
+    emit('job-started', data.job_id, { pauseAfterStage: pauseAfterStage.value })
+  } catch (e: any) {
+    error.value = `Failed to start pipeline: ${e.message}`
+    running.value = false
+  }
+}
+
 function formatSize(bytes: number): string {
   if (bytes < 1024) return `${bytes}B`
   if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(0)}KB`
@@ -320,7 +350,8 @@ onMounted(loadSources)
             :class="['source-item', { selected: selectedTimeline === tl.id }]"
             @click="selectTimeline(tl)"
           >
-            <span class="source-id">{{ tl.name || tl.id.slice(0, 12) }}</span>
+            <span class="source-id">{{ tl.id.slice(0, 8) }}</span>
+            <span class="timeline-name" v-if="tl.name">{{ tl.name }}</span>
             <span class="source-meta">
               <span class="source-type-badge">{{ tl.status.toUpperCase() }}</span>
               <span v-if="tl.frame_count" class="source-count">{{ tl.frame_count }} frames</span>
@@ -344,6 +375,14 @@ onMounted(loadSources)
           </div>
         </div>
         <div v-else-if="selectedTimeline" class="source-empty">No jobs yet</div>
+        <button
+          v-if="selectedTimeline"
+          class="run-again-btn"
+          @click="runOnTimeline(selectedTimeline)"
+          :disabled="running"
+        >
+          {{ running ? 'Starting...' : 'Run again on this timeline' }}
+        </button>
       </div>
 
       <div class="source-actions">
@@ -441,7 +480,8 @@ onMounted(loadSources)
   font-weight: 600;
 }
 
-.source-id { font-family: var(--font-mono); }
+.source-id { font-family: var(--font-mono); color: var(--text-dim); font-size: 10px; }
+.timeline-name { font-size: var(--font-size-sm); }
 
 .source-meta {
   display: flex;
@@ -535,6 +575,20 @@ onMounted(loadSources)
 .run-btn:hover { opacity: 0.9; }
 .run-btn:disabled { opacity: 0.5; cursor: not-allowed; }
 
+.run-again-btn {
+  background: var(--surface-3);
+  color: var(--text-secondary);
+  border: 1px solid var(--surface-3);
+  border-radius: 4px;
+  padding: var(--space-1) var(--space-3);
+  font-family: var(--font-mono);
+  font-size: var(--font-size-sm);
+  cursor: pointer;
+  margin-top: var(--space-1);
+}
+.run-again-btn:hover { background: var(--status-live); color: #000; }
+.run-again-btn:disabled { opacity: 0.5; cursor: not-allowed; }
+
 .source-actions {
   flex-shrink: 0;
   display: flex;
diff --git a/ui/detection-app/src/stores/pipeline.ts b/ui/detection-app/src/stores/pipeline.ts
index 87d0b0b..59f9627 100644
--- a/ui/detection-app/src/stores/pipeline.ts
+++ b/ui/detection-app/src/stores/pipeline.ts
@@ -80,10 +80,19 @@ export const usePipelineStore = defineStore('pipeline', () => {
     editorStage.value = stage
   }
 
-  function closeEditor() {
-    layoutMode.value = 'normal'
+  function openCompare() {
+    layoutMode.value = 'compare'
     editorStage.value = null
-    sourceHasSelection.value = false
+  }
+
+  function closeEditor() {
+    // Reload to reinitialize panels with current job context
+    const url = new URL(window.location.href)
+    url.hash = ''
+    if (jobId.value) {
+      url.searchParams.set('job', jobId.value)
+    }
+    window.location.href = url.toString()
   }
 
   function reset() {
@@ -105,6 +114,6 @@ export const usePipelineStore = defineStore('pipeline', () => {
     checkpoints, error, layoutMode, editorStage, sourceHasSelection,
     isRunning, isPaused, canReplay, isEditing,
     setJob, setTimelineId, setStatus, updateNodes, setRunContext, setCheckpoints, setError,
-    openSourceSelector, openBBoxEditor, openStageEditor, closeEditor, reset,
+    openSourceSelector, openBBoxEditor, openStageEditor, openCompare, closeEditor, reset,
   }
 })