Merge pull request 'v0.12.1 — Unit Swap wizard, editable timeline, roster/tz fixes' (#54) from dev into main

Reviewed-on: #54
docs+chore: v0.12.1 — Unit Swap wizard, editable timeline, roster/tz fixes

CHANGELOG entry for the five commits that landed after the v0.12.0 tag:
two features (Unit Swap wizard at /tools/unit-swap, editable deployment
timeline on /unit/{id}) and two correctness fixes (RosterUnit.deployed
now flips on swap/unassign/promote; deployment timeline now respects
user timezone for both display and edits).  No schema migrations.

README bumped to v0.12.1 with new bullets for the post-v0.12.0 features
and several already-shipped items that were missing from the list (SFM
Event DB Manager, Deployment-History calendar + Gantt tabs, reusable
location-map partial).  backend/main.py VERSION constant bumped too.

CHANGELOG.md

@@ -5,6 +5,45 @@ All notable changes to Terra-View will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.12.1] - 2026-05-20
+
+Field-operations polish — three small features and two correctness fixes that smooth out the deployment workflow added in v0.12.0.  The new Unit Swap wizard and editable deployment timeline are the operator-facing items; the swap/unassign/promote roster-flag fix closes a long-standing data-consistency hole.
+
+### Added — Unit Swap wizard (`/tools/unit-swap`)
+
+- **Mobile-first 4-step wizard** for the common field operation: pick project → pick location → choose incoming unit (with optional modem swap) → review + confirm.  Designed for tap-driven use on a phone in the field; works on desktop too.
+- **Benched-candidate awareness**: `GET /api/projects/.../available-units?include_benched=true` and `available-modems?include_benched=true` now return units/modems with `deployed=False` alongside the active fleet — exactly the inventory a tech pulls off the shelf.  Each row carries a `deployed` boolean for badge rendering.  Default (`include_benched=false`) is unchanged, so the existing location-detail swap modal isn't affected.
+- **`POST /locations/{loc}/swap` enhancements**:
+    - Flips the incoming unit (and modem) back to `deployed=True` if either was on the bench, keeping the legacy `RosterUnit.deployed` flag consistent with the active-assignment signal.
+    - Adds the symmetric half of the orphan-pairing fix: when a newly-paired modem still claims a different seismograph (whose `deployed_with_modem_id` was never cleared in a past swap), the stale back-reference is broken before re-pairing.
+- **`locations-with-assignments`** response now includes `modem.deployed`, so the wizard can badge the current modem in the location card, "Keep current modem" choice, picker rows, and review screen.
+- Tile on `/tools` for discovery; sidebar entry in the Tools nav cluster.
+
+### Added — Editable deployment timeline on `/unit/{id}`
+
+- **Per-row inline edit (pencil icon)** on each assignment in the unit's Deployment Timeline.  Opens a modal with `assigned_at`, `assigned_until` (with an "open-ended" checkbox that clears the end date), and notes.  Saves via the existing `PATCH /api/projects/{pid}/assignments/{aid}`; delete (for misclicks) via the existing `DELETE`.
+- **"+ Add deployment record" button** at the top of the timeline for backfilling historical windows — useful when orphan events sit outside any assignment.  Modal flow: project → location → assigned_at → assigned_until (optional open-ended) → notes.
+- **Closed-window assignments** now accepted by `POST /api/projects/.../locations/{loc}/assign`: the blanket "location already has an active assignment" check became overlap detection against same-location windows.  Closed historical assignments that don't overlap an existing one are accepted (the backfill case).
+- After any save/delete the timeline reloads and the SFM-events list re-fetches, so previously-orphaned events flip to "attributed" when their timestamp now falls inside an assignment window.
+
+### Fixed
+
+- **`RosterUnit.deployed` now flips correctly on swap / unassign / promote-pending** (`POST /locations/{loc}/swap`, `POST /assignments/{aid}/unassign`, `POST /deployments/pending/{id}/promote`).  The legacy `deployed` flag drives heartbeat polling and benched-vs-deployed roster filters; before this fix, those three workflows ended an assignment without flipping the flag, so the outgoing unit kept being polled and showed up as "deployed" forever.  All three now: close the previous active assignment, break the outgoing unit's modem pairing (both directions), and set `deployed = False` on the outgoing unit.  Unassign and swap also clear the modem's back-reference.  Promote-pending additionally handles the case where the target location already has an active assignment — previously this silently created two active assignments at the same location; now the old one is closed (`assigned_until = pending.capture_time`, `status = completed`), the old unit benched + unpaired, and an `assignment_swapped` `UnitHistory` row is written.
+- **Deployment timeline now respects user timezone for display *and* edits.**  Timestamps were stored correctly as UTC but rendered raw — a 1:30 PM EDT swap displayed as "5:30" because the frontend sliced the naive UTC ISO string straight to the screen.  Two-sided fix:
+    - **Display**: `services/deployment_timeline.py` converts every emitted timestamp (`starts_at`, `ends_at`, `event_overlay.peak_pvs_at`, `last_event`) through `utc_to_local()` using the user's configured timezone from `UserPreferences` before serializing.  Frontend slicing keeps working — it just slices a local-time string now.
+    - **Write**: `PATCH /api/projects/{pid}/assignments/{aid}` and `POST /locations/{loc}/assign` interpret a *naive* `assigned_at` / `assigned_until` ISO string as the user's local time and convert to UTC via `local_to_utc()`.  Explicit tz-aware strings (`...Z` or `...+00:00`) skip the conversion, so programmatic callers that already speak UTC keep working.
+
+### Migration Notes
+
+No schema changes.  Static code-only release — pull and restart:
+
+```bash
+cd /home/serversdown/terra-view
+docker compose build terra-view && docker compose up -d terra-view
+```
+
+---
+
 ## [0.12.0] - 2026-05-17
 
 Field-deployment workflow + fleet-wide deployment views + SFM event DB management.  The headline is the mobile capture flow: a field tech can now arrive on site, take one photo of the installed seismograph, and walk away — classification (which project, which location) happens later at a desk through the new pending-deployment hopper.  EXIF GPS is auto-extracted on capture, so the resulting `UnitAssignment` lands with coordinates without anyone typing them.

README.md

@@ -1,4 +1,4 @@
-# Terra-View v0.12.0
+# Terra-View v0.12.1
 Backend API and HTMX-powered web interface for managing a mixed fleet of seismographs and field modems. Track deployments, monitor health in real time, merge roster intent with incoming telemetry, and control your fleet through a unified database and dashboard.
 
 ## Features
@@ -9,15 +9,20 @@ Backend API and HTMX-powered web interface for managing a mixed fleet of seismog
   - **Touch Optimized**: 44x44px minimum touch targets, hamburger menu, bottom navigation bar
   - **Mobile Card View**: Compact unit cards with status dots, tap-to-navigate locations, and detail modals
   - **Background Sync**: Queue edits while offline and automatically sync when connection returns
+- **Field-Deployment Workflow**: One-photo mobile capture at `/deploy` → desk-side classification at `/tools/pending-deployments` → automatic UnitAssignment creation with EXIF GPS
+- **Unit Swap Wizard** (`/tools/unit-swap`): mobile-first 4-step flow for swapping a vibration unit (and optionally its modem) at a monitoring location.  Surfaces benched-fleet candidates as eligible incoming units; cleans up stale modem back-references on swap
+- **Editable Deployment Timeline** on every unit detail page: inline edit / delete each assignment, plus an "Add deployment record" button for backfilling historical windows.  Frees-up previously-orphaned events when their timestamp now falls inside an assignment
 - **Web Dashboard**: Modern, responsive UI with dark/light mode, live HTMX updates, and integrated fleet map
 - **Fleet Monitoring**: Track deployed, benched, retired, and ignored units in separate buckets with unknown-emitter triage
 - **Roster Management**: Full CRUD + CSV import/export, device-type aware metadata, and inline actions from the roster tables
 - **Settings & Safeguards**: `/settings` page exposes roster stats, exports, replace-all imports, and danger-zone reset tools
 - **Device & Modem Metadata**: Capture calibration windows, modem pairings, phone/IP details, and addresses per unit
 - **Status Management**: Automatically mark deployed units as OK, Pending (>12h), or Missing (>24h) based on recent telemetry
-- **Data Ingestion**: Accept reports from emitter scripts via REST API
+- **SFM Event DB Manager** (`/admin/events`): cross-unit event browser with bulk false-trigger flagging and admin-only hard-delete (cleans on-disk binaries + sidecars too) for purging bogus events from misbehaving units
+- **Deployment-History Calendar + Gantt** (`/tools/deployment-history`): fleet-wide 12-month calendar with side-panel day drill-down, plus "Gantt by Project" / "Gantt by Unit" tabs
 - **Photo Management**: Upload and view photos for each unit
-- **Interactive Maps**: Leaflet-based maps showing unit locations with tap-to-navigate for mobile
+- **Interactive Maps**: Leaflet-based maps showing unit locations with tap-to-navigate for mobile (reusable location-map partial across project overview + Vibration tab)
+- **Timezone-Aware Timeline**: deployment assignments display and edit in the user's configured local timezone; UTC stays canonical on disk
 - **SQLite Storage**: Lightweight, file-based database for easy deployment
 - **Database Management**: Comprehensive backup and restore system
   - **Manual Snapshots**: Create on-demand backups with descriptions

backend/main.py

@@ -30,7 +30,7 @@ Base.metadata.create_all(bind=engine)
 ENVIRONMENT = os.getenv("ENVIRONMENT", "production")
 
 # Initialize FastAPI app
-VERSION = "0.12.0"
+VERSION = "0.12.1"
 if ENVIRONMENT == "development":
     _build = os.getenv("BUILD_NUMBER", "0")
     if _build and _build != "0":
@@ -291,6 +291,14 @@ async def pending_deployments_page(request: Request):
     return templates.TemplateResponse("admin/pending_deployments.html", {"request": request})
 
 
+@app.get("/tools/unit-swap", response_class=HTMLResponse)
+async def unit_swap_page(request: Request):
+    """Mobile-first wizard for swapping a vibration unit (and optionally its
+    modem) at a monitoring location.  Pick project → location → incoming
+    unit → modem decision → confirm → optional photo of the new install."""
+    return templates.TemplateResponse("admin/unit_swap.html", {"request": request})
+
+
 @app.get("/modems", response_class=HTMLResponse)
 async def modems_page(request: Request):
     """Field modems management dashboard"""

backend/routers/pending_deployments.py

@@ -336,6 +336,36 @@ async def promote_pending(
         db.add(location)
         db.flush()
 
+    # If this location already has an active assignment, the /deploy
+    # capture means someone replaced that unit in the field — close the
+    # old assignment, break the outgoing unit's modem pairing, and bench
+    # it so the heartbeat / polling subsystem stops chasing it.
+    existing_active = db.query(UnitAssignment).filter(
+        UnitAssignment.location_id == location.id,
+        UnitAssignment.assigned_until == None,  # noqa: E711
+    ).first()
+    if existing_active and existing_active.unit_id != pd.unit_id:
+        existing_active.assigned_until = pd.captured_at
+        existing_active.status = "completed"
+        old_unit = db.query(RosterUnit).filter_by(id=existing_active.unit_id).first()
+        if old_unit:
+            if old_unit.deployed_with_modem_id:
+                old_modem = db.query(RosterUnit).filter_by(
+                    id=old_unit.deployed_with_modem_id, device_type="modem"
+                ).first()
+                if old_modem and old_modem.deployed_with_unit_id == old_unit.id:
+                    old_modem.deployed_with_unit_id = None
+                old_unit.deployed_with_modem_id = None
+            if old_unit.deployed:
+                old_unit.deployed = False
+        _record_history(
+            db, unit_id=existing_active.unit_id,
+            change_type="assignment_swapped",
+            old_value=location.name,
+            new_value=f"superseded by /deploy capture → {pd.unit_id}",
+            notes=notes,
+        )
+
     # Create the assignment.  assigned_at = pending capture time (so
     # events emitted after the install are correctly attributed back
     # to this location).
@@ -354,6 +384,12 @@ async def promote_pending(
     db.add(assignment)
     db.flush()
 
+    # Incoming unit is in the field again — flip it back to deployed
+    # if it was on the bench (mirrors the swap endpoint).
+    incoming_unit = db.query(RosterUnit).filter_by(id=pd.unit_id).first()
+    if incoming_unit and not incoming_unit.deployed:
+        incoming_unit.deployed = True
+
     # Promote the pending row.
     pd.status                   = "assigned"
     pd.promoted_at              = datetime.utcnow()

backend/routers/project_locations.py

@@ -10,6 +10,7 @@ from fastapi.responses import HTMLResponse, JSONResponse
 from sqlalchemy.orm import Session
 from sqlalchemy import and_, or_
 from datetime import datetime
+from zoneinfo import ZoneInfo
 from typing import Optional
 import uuid
 import json
@@ -34,7 +35,7 @@ from backend.models import (
     ScheduledAction,
 )
 from backend.templates_config import templates
-from backend.utils.timezone import local_to_utc
+from backend.utils.timezone import local_to_utc, utc_to_local  # noqa: F401
 
 router = APIRouter(prefix="/api/projects/{project_id}", tags=["project-locations"])
 
@@ -262,6 +263,84 @@ async def get_project_locations_json(
     ]
 
 
+@router.get("/locations-with-assignments")
+async def get_locations_with_assignments(
+    project_id: str,
+    db: Session = Depends(get_db),
+    location_type: Optional[str] = Query(None),
+):
+    """
+    Locations + their currently-active assignment + current unit + paired modem
+    in one call.  Used by the Unit Swap tool's location picker so a field tech
+    can see what's deployed where without N+1 round-trips.
+
+    Empty locations come back with assignment/unit/modem all null.
+    Removed locations are always excluded — you don't swap onto a dead slot.
+    """
+    project = db.query(Project).filter_by(id=project_id).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    query = db.query(MonitoringLocation).filter_by(project_id=project_id).filter(
+        MonitoringLocation.removed_at == None  # noqa: E711
+    )
+    if location_type:
+        query = query.filter_by(location_type=location_type)
+    locations = query.order_by(MonitoringLocation.sort_order, MonitoringLocation.name).all()
+
+    results = []
+    for loc in locations:
+        assignment = db.query(UnitAssignment).filter(
+            and_(
+                UnitAssignment.location_id == loc.id,
+                UnitAssignment.assigned_until == None,  # noqa: E711
+            )
+        ).first()
+
+        unit_payload = None
+        modem_payload = None
+        if assignment:
+            unit = db.query(RosterUnit).filter_by(id=assignment.unit_id).first()
+            if unit:
+                unit_payload = {
+                    "id":           unit.id,
+                    "device_type":  unit.device_type,
+                    "unit_type":    unit.unit_type,
+                    "slm_model":    unit.slm_model,
+                    "deployed_with_modem_id": unit.deployed_with_modem_id,
+                }
+                if unit.deployed_with_modem_id:
+                    modem = db.query(RosterUnit).filter_by(
+                        id=unit.deployed_with_modem_id, device_type="modem"
+                    ).first()
+                    if modem:
+                        modem_payload = {
+                            "id":             modem.id,
+                            "hardware_model": modem.hardware_model,
+                            "ip_address":     modem.ip_address,
+                            "phone_number":   modem.phone_number,
+                            "deployed":       bool(modem.deployed),
+                        }
+
+        results.append({
+            "id":            loc.id,
+            "name":          loc.name,
+            "location_type": loc.location_type,
+            "description":   loc.description,
+            "address":       loc.address,
+            "coordinates":   loc.coordinates,
+            "assignment": {
+                "id":          assignment.id,
+                "assigned_at": assignment.assigned_at.isoformat() if assignment.assigned_at else None,
+                "notes":       assignment.notes,
+            } if assignment else None,
+            "unit":  unit_payload,
+            "modem": modem_payload,
+        })
+
+    return results
+
+
 @router.post("/locations/create")
 async def create_location(
     project_id: str,
@@ -645,6 +724,19 @@ async def assign_unit_to_location(
 ):
     """
     Assign a unit to a monitoring location.
+
+    Accepts form fields:
+      - unit_id        — required
+      - assigned_at    — optional ISO datetime; defaults to now.  Set this
+                         when backfilling a historical deployment whose
+                         events landed in the orphan bucket.
+      - assigned_until — optional ISO datetime; absent = open-ended /
+                         active.
+      - notes          — optional free text
+
+    Refuses only when the *new window would overlap* an existing active
+    open-ended assignment at the same location.  Closed historical windows
+    that don't overlap are allowed (and required for orphan-event backfill).
     """
     location = db.query(MonitoringLocation).filter_by(
         id=location_id,
@@ -670,23 +762,50 @@ async def assign_unit_to_location(
             detail=f"Unit type '{unit.device_type}' does not match location type '{location.location_type}'",
         )
 
-    # Check if location already has an active assignment (active = assigned_until IS NULL)
+    # Parse dates.  Naive datetimes from datetime-local inputs are
-    existing_assignment = db.query(UnitAssignment).filter(
+    # interpreted as user-local and converted to UTC for storage; explicit
-        and_(
+    # tz-aware ISO strings (Z / +00:00) skip the conversion.
-            UnitAssignment.location_id == location_id,
+    def _parse_user_dt(s: str | None, field: str):
-            UnitAssignment.assigned_until == None,
+        if not s:
-        )
+            return None
-    ).first()
+        try:
+            parsed = datetime.fromisoformat(s)
+        except (TypeError, ValueError):
+            raise HTTPException(status_code=400, detail=f"Invalid {field}: {s!r}")
+        if parsed.tzinfo is None:
+            return local_to_utc(parsed)
+        return parsed.astimezone(ZoneInfo("UTC")).replace(tzinfo=None)
 
-    if existing_assignment:
+    assigned_at    = _parse_user_dt(form_data.get("assigned_at"),    "assigned_at") or datetime.utcnow()
+    assigned_until = _parse_user_dt(form_data.get("assigned_until"), "assigned_until")
+    if assigned_until is not None and assigned_until <= assigned_at:
         raise HTTPException(
-            status_code=400,
+            status_code=400, detail="assigned_until must be after assigned_at.",
-            detail=f"Location already has an active unit assignment ({existing_assignment.unit_id}). Use swap to replace it.",
         )
 
-    # Create new assignment
+    # Reject only if the new window overlaps an existing assignment at the
-    assigned_until_str = form_data.get("assigned_until")
+    # SAME location.  Closed historical windows that sit before the current
-    assigned_until = datetime.fromisoformat(assigned_until_str) if assigned_until_str else None
+    # active assignment are fine — that's the backfill case.
+    new_end_for_overlap = assigned_until or datetime.utcnow()
+    existing = db.query(UnitAssignment).filter(
+        UnitAssignment.location_id == location_id
+    ).all()
+    for other in existing:
+        other_start = other.assigned_at
+        other_end   = other.assigned_until or datetime.utcnow()
+        if assigned_at < other_end and new_end_for_overlap > other_start:
+            other_window = (
+                f"{other.assigned_at:%Y-%m-%d}"
+                + (f" → {other.assigned_until:%Y-%m-%d}" if other.assigned_until else " → present")
+            )
+            raise HTTPException(
+                status_code=400,
+                detail=(
+                    f"New window overlaps an existing assignment at this "
+                    f"location ({other.unit_id} {other_window}). Use swap or "
+                    f"edit that record instead."
+                ),
+            )
 
     assignment = UnitAssignment(
         id=str(uuid.uuid4()),
@@ -694,8 +813,9 @@ async def assign_unit_to_location(
         location_id=location_id,
         project_id=project_id,
         device_type=unit.device_type,
+        assigned_at=assigned_at,
         assigned_until=assigned_until,
-        status="active",
+        status="active" if assigned_until is None else "completed",
         notes=form_data.get("notes"),
     )
 
@@ -752,6 +872,20 @@ async def unassign_unit(
     assignment.status = "completed"
     assignment.assigned_until = datetime.utcnow()
 
+    # Unit is leaving the field — bench it so the heartbeat / polling
+    # subsystem stops chasing it.  Also break the modem pairing both ways.
+    unit = db.query(RosterUnit).filter_by(id=assignment.unit_id).first()
+    if unit:
+        if unit.deployed_with_modem_id:
+            modem = db.query(RosterUnit).filter_by(
+                id=unit.deployed_with_modem_id, device_type="modem"
+            ).first()
+            if modem and modem.deployed_with_unit_id == unit.id:
+                modem.deployed_with_unit_id = None
+            unit.deployed_with_modem_id = None
+        if unit.deployed:
+            unit.deployed = False
+
     location = db.query(MonitoringLocation).filter_by(id=assignment.location_id).first()
     _record_assignment_history(
         db,
@@ -786,6 +920,11 @@ async def update_assignment(
       - assigned_until: ISO datetime, or null/"" to mark indefinite (active)
       - notes:          string
 
+    Naive datetimes (no tz suffix) are interpreted as the user's
+    configured timezone and converted to UTC for storage.  Send an
+    explicit "+00:00" / "Z" suffix to skip the conversion (programmatic
+    callers that already have UTC).
+
     Sets `status` to "active" when assigned_until is cleared, "completed"
     when it's set in the past.
     """
@@ -816,12 +955,14 @@ async def update_assignment(
             )
         try:
             # Accept "YYYY-MM-DDTHH:MM" from datetime-local inputs or full ISO.
-            new_assigned_at = datetime.fromisoformat(raw)
+            parsed = datetime.fromisoformat(raw)
         except (TypeError, ValueError):
             raise HTTPException(
                 status_code=400,
                 detail=f"Invalid assigned_at datetime: {raw!r}",
             )
+        # Naive (no tz) → treat as user's local time and store as UTC.
+        new_assigned_at = local_to_utc(parsed) if parsed.tzinfo is None else parsed.astimezone(ZoneInfo("UTC")).replace(tzinfo=None)
 
     if "assigned_until" in payload:
         raw = payload["assigned_until"]
@@ -829,12 +970,13 @@ async def update_assignment(
             new_assigned_until = None
         else:
             try:
-                new_assigned_until = datetime.fromisoformat(raw)
+                parsed = datetime.fromisoformat(raw)
             except (TypeError, ValueError):
                 raise HTTPException(
                     status_code=400,
                     detail=f"Invalid assigned_until datetime: {raw!r}",
                 )
+            new_assigned_until = local_to_utc(parsed) if parsed.tzinfo is None else parsed.astimezone(ZoneInfo("UTC")).replace(tzinfo=None)
 
     if "notes" in payload:
         raw = payload["notes"]
@@ -1192,6 +1334,22 @@ async def swap_unit_on_location(
                 new_value=f"swapped out → {unit_id}",
                 notes=notes,
             )
+            # Clear the outgoing unit's modem pairing so the bidirectional
+            # deployed_with_modem_id / deployed_with_unit_id back-reference
+            # doesn't orphan onto the unit that just left the field.
+            old_unit = db.query(RosterUnit).filter_by(id=current.unit_id).first()
+            if old_unit:
+                if old_unit.deployed_with_modem_id:
+                    old_modem = db.query(RosterUnit).filter_by(
+                        id=old_unit.deployed_with_modem_id, device_type="modem"
+                    ).first()
+                    if old_modem and old_modem.deployed_with_unit_id == current.unit_id:
+                        old_modem.deployed_with_unit_id = None
+                    old_unit.deployed_with_modem_id = None
+                # Bench the outgoing unit — it's no longer in the field, so
+                # the heartbeat / polling subsystem should stop chasing it.
+                if old_unit.deployed:
+                    old_unit.deployed = False
 
     # Create new assignment
     new_assignment = UnitAssignment(
@@ -1218,12 +1376,28 @@ async def swap_unit_on_location(
         modem = db.query(RosterUnit).filter_by(id=modem_id, device_type="modem").first()
         if not modem:
             raise HTTPException(status_code=404, detail=f"Modem '{modem_id}' not found")
+        # Symmetric cleanup: if this modem still claims a previous partner
+        # (a different seismograph whose deployed_with_modem_id never got
+        # cleared in a past swap), break that stale link before re-pairing.
+        if modem.deployed_with_unit_id and modem.deployed_with_unit_id != unit_id:
+            prev_partner = db.query(RosterUnit).filter_by(id=modem.deployed_with_unit_id).first()
+            if prev_partner and prev_partner.deployed_with_modem_id == modem_id:
+                prev_partner.deployed_with_modem_id = None
         unit.deployed_with_modem_id = modem_id
         modem.deployed_with_unit_id = unit_id
+        # If the modem was on the bench, swapping it into the field puts it
+        # back in rotation.
+        if not modem.deployed:
+            modem.deployed = True
     else:
         # Clear modem pairing if not provided
         unit.deployed_with_modem_id = None
 
+    # If the incoming unit was benched, putting it in the field flips it
+    # back to deployed (so polling / dashboards see it as in rotation).
+    if not unit.deployed:
+        unit.deployed = True
+
     db.commit()
 
     return JSONResponse({
@@ -1241,23 +1415,32 @@ async def swap_unit_on_location(
 async def get_available_modems(
     project_id: str,
     db: Session = Depends(get_db),
+    include_benched: bool = Query(False),
 ):
     """
-    Get all deployed, non-retired modems for the modem assignment dropdown.
+    Get all non-retired modems for the modem assignment dropdown.
+
+    By default only deployed (in-rotation) modems are returned, preserving
+    the existing behavior for callers like the location-detail swap modal.
+    Pass ``include_benched=true`` to also include benched modems
+    (``RosterUnit.deployed == False``) — useful when picking a modem to
+    pull off the bench for a field swap.  Each row's ``deployed`` flag is
+    returned so the UI can badge benched candidates.
     """
-    modems = db.query(RosterUnit).filter(
+    filters = [
-        and_(
+        RosterUnit.device_type == "modem",
-            RosterUnit.device_type == "modem",
+        RosterUnit.retired == False,
-            RosterUnit.deployed == True,
+    ]
-            RosterUnit.retired == False,
+    if not include_benched:
-        )
+        filters.append(RosterUnit.deployed == True)
-    ).order_by(RosterUnit.id).all()
+    modems = db.query(RosterUnit).filter(and_(*filters)).order_by(RosterUnit.id).all()
 
     return [
         {
             "id": m.id,
             "hardware_model": m.hardware_model,
             "ip_address": m.ip_address,
+            "deployed": bool(m.deployed),
         }
         for m in modems
     ]
@@ -1268,22 +1451,31 @@ async def get_available_units(
     project_id: str,
     location_type: str = Query(...),
     db: Session = Depends(get_db),
+    include_benched: bool = Query(False),
 ):
     """
     Get list of available units for assignment to a location.
     Filters by device type matching the location type.
+
+    By default only deployed (in-rotation) units are returned, preserving
+    the existing location-detail swap-modal behavior.  Pass
+    ``include_benched=true`` to also include benched units
+    (``RosterUnit.deployed == False``) — exactly the candidates you'd
+    pull off the bench for a field swap.  Each row carries a ``deployed``
+    flag so the UI can badge benched picks.
     """
     # Determine required device type
     required_device_type = "slm" if location_type == "sound" else "seismograph"
 
-    # Get all units of the required type that are deployed and not retired
+    # Get all units of the required type that aren't retired (and optionally
-    all_units = db.query(RosterUnit).filter(
+    # exclude benched units).
-        and_(
+    filters = [
-            RosterUnit.device_type == required_device_type,
+        RosterUnit.device_type == required_device_type,
-            RosterUnit.deployed == True,
+        RosterUnit.retired == False,
-            RosterUnit.retired == False,
+    ]
-        )
+    if not include_benched:
-    ).all()
+        filters.append(RosterUnit.deployed == True)
+    all_units = db.query(RosterUnit).filter(and_(*filters)).all()
 
     # Filter out units that already have active assignments (active = assigned_until IS NULL)
     assigned_unit_ids = db.query(UnitAssignment.unit_id).filter(
@@ -1297,6 +1489,7 @@ async def get_available_units(
             "device_type": unit.device_type,
             "location": unit.address or unit.location,
             "model": unit.slm_model if unit.device_type == "slm" else unit.unit_type,
+            "deployed": bool(unit.deployed),
         }
         for unit in all_units
         if unit.id not in assigned_unit_ids

backend/services/deployment_timeline.py

@@ -39,9 +39,35 @@ from backend.services.sfm_events import (
     _fetch_events_for_serial,
     _iso_utc,
 )
+from backend.utils.timezone import utc_to_local
 
 log = logging.getLogger("backend.services.deployment_timeline")
 
+
+def _iso_local(dt) -> Optional[str]:
+    """Serialize a datetime / ISO-string in the user's configured timezone.
+
+    The timeline frontend slices these strings to character 19 to produce
+    "YYYY-MM-DD HH:MM:SS" — no JS-side timezone conversion happens.  We
+    therefore emit *already-local* timestamps here so the displayed time
+    matches what the operator actually saw on the wall clock.
+
+    Accepts either a ``datetime`` (DB column) or an ISO ``str`` (SFM
+    response).  Returns ``None`` for ``None`` input.  Naive ISO strings
+    from SFM are interpreted as UTC.
+    """
+    if dt is None:
+        return None
+    if isinstance(dt, str):
+        try:
+            dt = datetime.fromisoformat(dt.replace("Z", "").replace(" ", "T"))
+        except ValueError:
+            return dt   # give up gracefully — emit whatever SFM sent
+    local = utc_to_local(dt)
+    if local is None:
+        return None
+    return local.replace(tzinfo=None).isoformat()
+
 # Don't emit synthetic gap entries shorter than this (seconds).  Avoids visual
 # clutter from a sub-second handoff during a swap workflow.
 _MIN_GAP_SECONDS = 24 * 3600  # 1 day
@@ -185,8 +211,8 @@ async def deployment_timeline_for_unit(
             overlays[a.id] = {
                 "event_count": len(events),
                 "peak_pvs":    peak,
-                "peak_pvs_at": peak_at,
+                "peak_pvs_at": _iso_local(peak_at),
-                "last_event":  last_ev,
+                "last_event":  _iso_local(last_ev),
             }
 
     # 4. Build entries.  Start by emitting assignment rows + gap rows between
@@ -202,8 +228,8 @@ async def deployment_timeline_for_unit(
 
         entry = {
             "kind":          "assignment",
-            "starts_at":     _iso_utc(a.assigned_at),
+            "starts_at":     _iso_local(a.assigned_at),
-            "ends_at":       _iso_utc(a.assigned_until),
+            "ends_at":       _iso_local(a.assigned_until),
             "duration_days": round(duration_days, 1) if duration_days is not None else None,
             "assignment_id": a.id,
             "location_id":   a.location_id,
@@ -227,8 +253,8 @@ async def deployment_timeline_for_unit(
             if gap_seconds >= _MIN_GAP_SECONDS:
                 entries.append({
                     "kind":          "gap",
-                    "starts_at":     _iso_utc(gap_start),
+                    "starts_at":     _iso_local(gap_start),
-                    "ends_at":       _iso_utc(gap_end),
+                    "ends_at":       _iso_local(gap_end),
                     "duration_days": round(gap_seconds / 86400, 1),
                     "context":       "between assignments",
                 })
@@ -241,7 +267,7 @@ async def deployment_timeline_for_unit(
             continue
         entries.append({
             "kind":          "state_change",
-            "starts_at":     _iso_utc(h.changed_at),
+            "starts_at":     _iso_local(h.changed_at),
             "ends_at":       None,
             "duration_days": None,
             "change_type":   h.change_type,

templates/admin/unit_swap.html

@@ -0,0 +1,728 @@
+{% extends "base.html" %}
+
+{% block title %}Unit Swap - Seismo Fleet Manager{% endblock %}
+
+{% block content %}
+<div class="max-w-md mx-auto">
+    <div class="mb-4 flex items-center justify-between">
+        <div>
+            <h1 class="text-2xl font-bold text-gray-900 dark:text-white">Unit Swap</h1>
+            <p class="text-sm text-gray-500 dark:text-gray-400 mt-1">
+                Swap a vibration unit (and modem) at a monitoring location.
+            </p>
+        </div>
+        <a href="/tools" class="text-xs text-seismo-orange hover:text-seismo-burgundy whitespace-nowrap">← Tools</a>
+    </div>
+
+    <!-- Stepper -->
+    <div class="flex items-center justify-between mb-4 text-[11px] text-gray-500 dark:text-gray-400">
+        <div id="swap-pill-1" class="flex items-center gap-1 text-seismo-orange font-medium">
+            <span class="w-5 h-5 rounded-full bg-seismo-orange text-white inline-flex items-center justify-center text-[10px]">1</span>
+            Project
+        </div>
+        <div class="flex-1 h-px bg-gray-200 dark:bg-gray-700 mx-1"></div>
+        <div id="swap-pill-2" class="flex items-center gap-1">
+            <span class="w-5 h-5 rounded-full bg-gray-200 dark:bg-gray-700 inline-flex items-center justify-center text-[10px]">2</span>
+            Location
+        </div>
+        <div class="flex-1 h-px bg-gray-200 dark:bg-gray-700 mx-1"></div>
+        <div id="swap-pill-3" class="flex items-center gap-1">
+            <span class="w-5 h-5 rounded-full bg-gray-200 dark:bg-gray-700 inline-flex items-center justify-center text-[10px]">3</span>
+            Unit
+        </div>
+        <div class="flex-1 h-px bg-gray-200 dark:bg-gray-700 mx-1"></div>
+        <div id="swap-pill-4" class="flex items-center gap-1">
+            <span class="w-5 h-5 rounded-full bg-gray-200 dark:bg-gray-700 inline-flex items-center justify-center text-[10px]">4</span>
+            Modem
+        </div>
+        <div class="flex-1 h-px bg-gray-200 dark:bg-gray-700 mx-1"></div>
+        <div id="swap-pill-5" class="flex items-center gap-1">
+            <span class="w-5 h-5 rounded-full bg-gray-200 dark:bg-gray-700 inline-flex items-center justify-center text-[10px]">5</span>
+            Confirm
+        </div>
+    </div>
+
+    <!-- Step 1: Project picker -->
+    <div id="swap-step-1" class="bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 space-y-3">
+        <label class="block">
+            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Which project?</span>
+            <input id="swap-project-search" type="search" autocomplete="off"
+                   placeholder="Filter by number, client, or name…"
+                   class="mt-2 w-full px-3 py-3 text-base border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+        </label>
+        <div id="swap-project-list" class="max-h-96 overflow-y-auto space-y-1.5"></div>
+    </div>
+
+    <!-- Step 2: Location picker -->
+    <div id="swap-step-2" class="hidden bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 space-y-3">
+        <div class="flex items-center justify-between">
+            <div class="min-w-0">
+                <p class="text-xs text-gray-500 dark:text-gray-400">Project</p>
+                <p class="font-semibold text-seismo-orange truncate" id="swap-project-label">—</p>
+            </div>
+            <button onclick="swapGoToStep(1)" class="text-xs text-gray-500 hover:text-seismo-orange whitespace-nowrap">Change</button>
+        </div>
+        <div>
+            <p class="text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">Which location?</p>
+            <div id="swap-location-list" class="max-h-96 overflow-y-auto space-y-1.5"></div>
+        </div>
+    </div>
+
+    <!-- Step 3: New unit picker -->
+    <div id="swap-step-3" class="hidden bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 space-y-3">
+        <div class="flex items-center justify-between">
+            <div class="min-w-0 flex-1">
+                <p class="text-xs text-gray-500 dark:text-gray-400">Swapping at</p>
+                <p class="font-semibold text-seismo-orange truncate" id="swap-location-label">—</p>
+                <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">
+                    Out: <span id="swap-old-unit-label" class="font-mono">—</span>
+                </p>
+            </div>
+            <button onclick="swapGoToStep(2)" class="text-xs text-gray-500 hover:text-seismo-orange whitespace-nowrap">Change</button>
+        </div>
+        <label class="block">
+            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Incoming unit</span>
+            <input id="swap-unit-search" type="search" autocomplete="off"
+                   placeholder="Filter by serial…"
+                   class="mt-2 w-full px-3 py-3 text-base border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+            <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Only seismographs without an active assignment.</p>
+        </label>
+        <div id="swap-unit-list" class="max-h-72 overflow-y-auto space-y-1.5"></div>
+    </div>
+
+    <!-- Step 4: Modem decision -->
+    <div id="swap-step-4" class="hidden bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 space-y-4">
+        <div class="flex items-center justify-between">
+            <div class="min-w-0 flex-1">
+                <p class="text-xs text-gray-500 dark:text-gray-400">Incoming</p>
+                <p class="font-mono font-semibold text-seismo-orange" id="swap-new-unit-label">—</p>
+            </div>
+            <button onclick="swapGoToStep(3)" class="text-xs text-gray-500 hover:text-seismo-orange whitespace-nowrap">Change</button>
+        </div>
+
+        <div>
+            <p class="text-sm font-medium text-gray-700 dark:text-gray-300 mb-2" id="swap-modem-question">Modem?</p>
+            <div id="swap-modem-choice-list" class="space-y-2"></div>
+        </div>
+
+        <div id="swap-modem-picker-wrap" class="hidden">
+            <label class="block">
+                <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Pick a modem</span>
+                <input id="swap-modem-search" type="search" autocomplete="off"
+                       placeholder="Filter modems…"
+                       class="mt-2 w-full px-3 py-3 text-base border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+            </label>
+            <div id="swap-modem-list" class="max-h-60 overflow-y-auto space-y-1.5 mt-2"></div>
+        </div>
+
+        <button id="swap-modem-next"
+                onclick="swapAfterModem()"
+                class="w-full px-4 py-3 bg-seismo-orange hover:bg-orange-600 text-white rounded-lg font-medium text-base disabled:opacity-50 disabled:cursor-not-allowed"
+                disabled>
+            Continue
+        </button>
+    </div>
+
+    <!-- Step 5: Review + confirm -->
+    <div id="swap-step-5" class="hidden bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 space-y-4">
+        <h3 class="text-lg font-semibold text-gray-900 dark:text-white">Review the swap</h3>
+
+        <dl class="text-sm space-y-2">
+            <div class="flex justify-between gap-2">
+                <dt class="text-gray-500 dark:text-gray-400">Project</dt>
+                <dd class="text-right text-gray-900 dark:text-white font-medium truncate" id="swap-review-project">—</dd>
+            </div>
+            <div class="flex justify-between gap-2">
+                <dt class="text-gray-500 dark:text-gray-400">Location</dt>
+                <dd class="text-right text-gray-900 dark:text-white font-medium truncate" id="swap-review-location">—</dd>
+            </div>
+            <div class="border-t border-gray-200 dark:border-gray-700 pt-2 flex justify-between gap-2">
+                <dt class="text-gray-500 dark:text-gray-400">Unit out</dt>
+                <dd class="text-right font-mono text-gray-900 dark:text-white" id="swap-review-old-unit">—</dd>
+            </div>
+            <div class="flex justify-between gap-2">
+                <dt class="text-gray-500 dark:text-gray-400">Unit in</dt>
+                <dd class="text-right font-mono text-seismo-orange font-semibold" id="swap-review-new-unit">—</dd>
+            </div>
+            <div class="border-t border-gray-200 dark:border-gray-700 pt-2 flex justify-between gap-2">
+                <dt class="text-gray-500 dark:text-gray-400">Modem out</dt>
+                <dd class="text-right font-mono text-gray-900 dark:text-white" id="swap-review-old-modem">—</dd>
+            </div>
+            <div class="flex justify-between gap-2">
+                <dt class="text-gray-500 dark:text-gray-400">Modem in</dt>
+                <dd class="text-right font-mono text-seismo-orange font-semibold" id="swap-review-new-modem">—</dd>
+            </div>
+        </dl>
+
+        <label class="block">
+            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Notes (optional)</span>
+            <textarea id="swap-notes" rows="2"
+                      placeholder="Reason for swap, anything to remember…"
+                      class="mt-2 w-full px-3 py-2 text-base border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white"></textarea>
+        </label>
+
+        <div id="swap-error" class="hidden text-sm text-red-600"></div>
+
+        <button id="swap-confirm-btn"
+                onclick="swapConfirm()"
+                class="w-full px-4 py-3 bg-seismo-orange hover:bg-orange-600 text-white rounded-lg font-medium text-base">
+            Confirm swap
+        </button>
+        <button onclick="swapGoToStep(4)" class="w-full text-sm text-gray-500 hover:text-seismo-orange">← Back</button>
+    </div>
+
+    <!-- Step 6: Success + optional photo -->
+    <div id="swap-step-done" class="hidden bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 space-y-4">
+        <div class="text-center">
+            <div class="w-14 h-14 mx-auto rounded-full bg-green-100 dark:bg-green-900/30 flex items-center justify-center">
+                <svg class="w-8 h-8 text-green-600 dark:text-green-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 13l4 4L19 7"/>
+                </svg>
+            </div>
+            <h3 class="text-lg font-semibold text-gray-900 dark:text-white mt-3">Swap complete</h3>
+            <p class="text-sm text-gray-500 dark:text-gray-400 mt-1" id="swap-done-summary">—</p>
+        </div>
+
+        <div class="border-t border-gray-200 dark:border-gray-700 pt-4">
+            <p class="text-sm font-medium text-gray-700 dark:text-gray-300">Add a photo of the new install?</p>
+            <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Optional. EXIF GPS will populate the unit's coordinates.</p>
+            <input id="swap-photo-input" type="file" accept="image/*" capture="environment"
+                   onchange="swapOnPhotoPicked(event)"
+                   class="mt-2 w-full text-sm text-gray-500 file:mr-4 file:py-3 file:px-4 file:rounded-lg file:border-0 file:text-sm file:font-semibold file:bg-seismo-orange file:text-white hover:file:bg-orange-600">
+            <div id="swap-photo-preview-wrap" class="hidden mt-3">
+                <img id="swap-photo-preview" class="w-full rounded-lg border border-gray-200 dark:border-gray-700" alt="">
+            </div>
+            <div id="swap-photo-error" class="hidden text-sm text-red-600 mt-2"></div>
+            <div id="swap-photo-status" class="hidden text-sm text-green-600 mt-2"></div>
+        </div>
+
+        <div class="grid grid-cols-2 gap-2">
+            <button id="swap-photo-upload-btn"
+                    onclick="swapUploadPhoto()"
+                    class="px-4 py-3 bg-seismo-orange hover:bg-orange-600 text-white rounded-lg font-medium disabled:opacity-50 disabled:cursor-not-allowed"
+                    disabled>
+                Upload photo
+            </button>
+            <button onclick="swapReset()"
+                    class="px-4 py-3 border border-gray-300 dark:border-gray-600 hover:bg-gray-50 dark:hover:bg-gray-700 text-gray-700 dark:text-gray-300 rounded-lg font-medium">
+                Done — another swap
+            </button>
+        </div>
+    </div>
+</div>
+
+<script>
+const _swap = {
+    step: 1,
+    project: null,        // { id, display, ... }
+    location: null,       // { id, name, unit, modem }
+    new_unit: null,       // { id, ... }
+    modem_action: null,   // 'keep' | 'swap' | 'remove' | 'add' | 'none'
+    new_modem: null,      // { id, ... }
+    all_projects: [],
+    all_units: [],
+    all_modems: [],
+    swap_result: null,
+    photo_file: null,
+    photo_preview_url: null,
+};
+
+function _esc(s) {
+    if (s == null) return '';
+    return String(s).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;');
+}
+
+function _badge(deployed) {
+    return deployed
+        ? '<span class="text-[10px] uppercase tracking-wider px-1.5 py-0.5 rounded bg-green-100 text-green-800 dark:bg-green-900/30 dark:text-green-300">deployed</span>'
+        : '<span class="text-[10px] uppercase tracking-wider px-1.5 py-0.5 rounded bg-amber-100 text-amber-800 dark:bg-amber-900/30 dark:text-amber-300">benched</span>';
+}
+
+function swapGoToStep(n) {
+    _swap.step = n;
+    for (let i = 1; i <= 5; i++) {
+        const el = document.getElementById('swap-step-' + i);
+        if (el) el.classList.toggle('hidden', i !== n);
+        const pill = document.getElementById('swap-pill-' + i);
+        if (!pill) continue;
+        const dot = pill.querySelector('span');
+        if (i === n) {
+            pill.classList.remove('text-gray-500', 'dark:text-gray-400');
+            pill.classList.add('text-seismo-orange', 'font-medium');
+            dot.classList.remove('bg-gray-200', 'dark:bg-gray-700');
+            dot.classList.add('bg-seismo-orange', 'text-white');
+        } else if (i < n) {
+            pill.classList.remove('text-gray-500', 'dark:text-gray-400');
+            pill.classList.add('text-green-600', 'dark:text-green-400');
+            dot.classList.remove('bg-gray-200', 'dark:bg-gray-700', 'bg-seismo-orange', 'text-white');
+            dot.classList.add('bg-green-100', 'dark:bg-green-900/30', 'text-green-700', 'dark:text-green-300');
+        } else {
+            pill.classList.add('text-gray-500', 'dark:text-gray-400');
+            pill.classList.remove('text-seismo-orange', 'font-medium', 'text-green-600', 'dark:text-green-400');
+            dot.classList.add('bg-gray-200', 'dark:bg-gray-700');
+            dot.classList.remove('bg-seismo-orange', 'text-white', 'bg-green-100', 'dark:bg-green-900/30', 'text-green-700', 'dark:text-green-300');
+        }
+    }
+    document.getElementById('swap-step-done').classList.add('hidden');
+}
+
+// ── Step 1: project picker ──────────────────────────────────────────
+async function _swapLoadProjects() {
+    const list = document.getElementById('swap-project-list');
+    list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">Loading…</p>';
+    try {
+        const r = await fetch('/api/projects/search-json?limit=50');
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        _swap.all_projects = await r.json();
+        _swapRenderProjects();
+    } catch (e) {
+        list.innerHTML = `<p class="text-sm text-red-500 px-3 py-2">Load failed: ${_esc(e.message)}</p>`;
+    }
+}
+
+function _swapRenderProjects() {
+    const q = document.getElementById('swap-project-search').value.trim().toLowerCase();
+    const list = document.getElementById('swap-project-list');
+    let items = _swap.all_projects;
+    if (q) {
+        items = items.filter(p => {
+            const hay = [(p.project_number||''), (p.client_name||''), (p.name||''), (p.display||'')]
+                .join(' ').toLowerCase();
+            return hay.includes(q);
+        });
+    }
+    if (items.length === 0) {
+        list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">No matching projects.</p>';
+        return;
+    }
+    list.innerHTML = items.map(p => {
+        const num = p.project_number ? `<span class="font-mono text-xs text-gray-500 dark:text-gray-400">${_esc(p.project_number)}</span>` : '';
+        const client = p.client_name ? `<div class="text-xs text-gray-500 dark:text-gray-400 truncate">${_esc(p.client_name)}</div>` : '';
+        return `<button onclick='swapPickProject(${JSON.stringify(p.id)})'
+            class="w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+            <div class="flex items-center justify-between gap-2">
+                <span class="font-semibold text-gray-900 dark:text-white truncate">${_esc(p.name)}</span>
+                ${num}
+            </div>
+            ${client}
+        </button>`;
+    }).join('');
+}
+
+function swapPickProject(projectId) {
+    const p = _swap.all_projects.find(x => x.id === projectId);
+    if (!p) return;
+    _swap.project = p;
+    document.getElementById('swap-project-label').textContent = p.name;
+    _swapLoadLocations();
+    swapGoToStep(2);
+}
+
+// ── Step 2: location picker ─────────────────────────────────────────
+async function _swapLoadLocations() {
+    const list = document.getElementById('swap-location-list');
+    list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">Loading…</p>';
+    try {
+        const r = await fetch(`/api/projects/${encodeURIComponent(_swap.project.id)}/locations-with-assignments?location_type=vibration`);
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        const data = await r.json();
+        _swapRenderLocations(data);
+    } catch (e) {
+        list.innerHTML = `<p class="text-sm text-red-500 px-3 py-2">Load failed: ${_esc(e.message)}</p>`;
+    }
+}
+
+function _swapRenderLocations(locations) {
+    const list = document.getElementById('swap-location-list');
+    if (!locations || locations.length === 0) {
+        list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">No vibration locations in this project.</p>';
+        return;
+    }
+    list.innerHTML = locations.map(loc => {
+        const unit = loc.unit;
+        const modem = loc.modem;
+        const unitLine = unit
+            ? `<div class="text-xs text-gray-600 dark:text-gray-300 font-mono">${_esc(unit.id)}<span class="text-gray-400">${unit.unit_type ? ' · ' + _esc(unit.unit_type) : ''}</span></div>`
+            : `<div class="text-xs italic text-gray-400">Empty — first assign</div>`;
+        const modemLine = modem
+            ? `<div class="text-[11px] text-gray-500 dark:text-gray-400 font-mono mt-0.5 flex items-center gap-2">
+                 <span>+ modem ${_esc(modem.id)}</span>
+                 ${_badge(modem.deployed)}
+               </div>`
+            : '';
+        // Pass index for cleaner attribute escaping
+        return `<button data-locidx="${locations.indexOf(loc)}" onclick="_swapPickLocationByIdx(this.dataset.locidx)"
+            class="w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+            <div class="flex items-center justify-between gap-2">
+                <span class="font-semibold text-gray-900 dark:text-white truncate">${_esc(loc.name)}</span>
+            </div>
+            ${unitLine}
+            ${modemLine}
+        </button>`;
+    }).join('');
+    _swap._locations_cache = locations;
+}
+
+function _swapPickLocationByIdx(idxStr) {
+    const idx = parseInt(idxStr, 10);
+    const loc = _swap._locations_cache[idx];
+    if (!loc) return;
+    _swap.location = loc;
+    document.getElementById('swap-location-label').textContent = loc.name;
+    document.getElementById('swap-old-unit-label').textContent = loc.unit ? loc.unit.id : '(empty)';
+    _swapLoadUnits();
+    swapGoToStep(3);
+}
+
+// ── Step 3: incoming unit picker ────────────────────────────────────
+async function _swapLoadUnits() {
+    const list = document.getElementById('swap-unit-list');
+    list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">Loading…</p>';
+    try {
+        const r = await fetch(`/api/projects/${encodeURIComponent(_swap.project.id)}/available-units?location_type=vibration&include_benched=true`);
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        _swap.all_units = await r.json();
+        _swapRenderUnits();
+    } catch (e) {
+        list.innerHTML = `<p class="text-sm text-red-500 px-3 py-2">Load failed: ${_esc(e.message)}</p>`;
+    }
+}
+
+function _swapRenderUnits() {
+    const q = document.getElementById('swap-unit-search').value.trim().toLowerCase();
+    const list = document.getElementById('swap-unit-list');
+    let items = _swap.all_units;
+    if (q) {
+        items = items.filter(u => {
+            const hay = [(u.id||''), (u.model||''), (u.location||'')].join(' ').toLowerCase();
+            return hay.includes(q);
+        });
+    }
+    if (items.length === 0) {
+        list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">No available seismographs.</p>';
+        return;
+    }
+    list.innerHTML = items.map(u => {
+        const model = u.model ? `<span class="text-xs text-gray-500 dark:text-gray-400">${_esc(u.model)}</span>` : '';
+        const loc = u.location ? `<div class="text-xs text-gray-500 dark:text-gray-400 truncate">${_esc(u.location)}</div>` : '';
+        const badge = _badge(u.deployed);
+        return `<button onclick='swapPickUnit(${JSON.stringify(u.id)})'
+            class="w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+            <div class="flex items-center justify-between gap-2">
+                <span class="font-mono font-semibold text-gray-900 dark:text-white">${_esc(u.id)}</span>
+                <div class="flex items-center gap-2">
+                    ${badge}
+                    ${model}
+                </div>
+            </div>
+            ${loc}
+        </button>`;
+    }).join('');
+}
+
+function swapPickUnit(unitId) {
+    const u = _swap.all_units.find(x => x.id === unitId);
+    if (!u) return;
+    _swap.new_unit = u;
+    document.getElementById('swap-new-unit-label').textContent = u.id;
+    _swapInitModemStep();
+    swapGoToStep(4);
+}
+
+// ── Step 4: modem decision ──────────────────────────────────────────
+function _swapInitModemStep() {
+    _swap.modem_action = null;
+    _swap.new_modem = null;
+    document.getElementById('swap-modem-picker-wrap').classList.add('hidden');
+    document.getElementById('swap-modem-next').disabled = true;
+
+    const current = _swap.location && _swap.location.modem;
+    const choices = document.getElementById('swap-modem-choice-list');
+    const question = document.getElementById('swap-modem-question');
+
+    if (current) {
+        question.textContent = 'Modem at this location';
+        choices.innerHTML = `
+            <button data-action="keep" onclick="swapPickModemAction('keep')"
+                class="swap-modem-choice w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+                <div class="flex items-center justify-between gap-2">
+                    <div class="font-medium text-gray-900 dark:text-white">Keep <span class="font-mono">${_esc(current.id)}</span></div>
+                    ${_badge(current.deployed)}
+                </div>
+                <div class="text-xs text-gray-500 dark:text-gray-400">Re-pair the existing modem to the incoming unit.</div>
+            </button>
+            <button data-action="swap" onclick="swapPickModemAction('swap')"
+                class="swap-modem-choice w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+                <div class="font-medium text-gray-900 dark:text-white">Swap modem too</div>
+                <div class="text-xs text-gray-500 dark:text-gray-400">Pick a different unassigned modem.</div>
+            </button>
+            <button data-action="remove" onclick="swapPickModemAction('remove')"
+                class="swap-modem-choice w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+                <div class="font-medium text-gray-900 dark:text-white">No modem</div>
+                <div class="text-xs text-gray-500 dark:text-gray-400">Incoming unit goes solo (no cellular).</div>
+            </button>`;
+    } else {
+        question.textContent = 'No modem at this location currently.';
+        choices.innerHTML = `
+            <button data-action="none" onclick="swapPickModemAction('none')"
+                class="swap-modem-choice w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+                <div class="font-medium text-gray-900 dark:text-white">No modem</div>
+                <div class="text-xs text-gray-500 dark:text-gray-400">Standalone / manual download.</div>
+            </button>
+            <button data-action="add" onclick="swapPickModemAction('add')"
+                class="swap-modem-choice w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors">
+                <div class="font-medium text-gray-900 dark:text-white">Add a modem</div>
+                <div class="text-xs text-gray-500 dark:text-gray-400">Pair an unassigned modem with the incoming unit.</div>
+            </button>`;
+    }
+}
+
+function swapPickModemAction(action) {
+    _swap.modem_action = action;
+    _swap.new_modem = null;
+    // Highlight the picked choice; dim the others.
+    document.querySelectorAll('.swap-modem-choice').forEach(btn => {
+        if (btn.dataset.action === action) {
+            btn.classList.add('border-seismo-orange', 'bg-amber-50', 'dark:bg-amber-900/10');
+        } else {
+            btn.classList.remove('border-seismo-orange', 'bg-amber-50', 'dark:bg-amber-900/10');
+        }
+    });
+
+    const pickerWrap = document.getElementById('swap-modem-picker-wrap');
+    const nextBtn = document.getElementById('swap-modem-next');
+
+    if (action === 'swap' || action === 'add') {
+        pickerWrap.classList.remove('hidden');
+        nextBtn.disabled = true;
+        _swapLoadModems();
+    } else {
+        pickerWrap.classList.add('hidden');
+        nextBtn.disabled = false;
+    }
+}
+
+async function _swapLoadModems() {
+    const list = document.getElementById('swap-modem-list');
+    list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">Loading…</p>';
+    try {
+        const r = await fetch(`/api/projects/${encodeURIComponent(_swap.project.id)}/available-modems?include_benched=true`);
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        // Filter out the modem that's currently at this location (it's the "keep" option, not "swap").
+        let modems = await r.json();
+        const currentModemId = _swap.location && _swap.location.modem ? _swap.location.modem.id : null;
+        if (currentModemId) modems = modems.filter(m => m.id !== currentModemId);
+        _swap.all_modems = modems;
+        _swapRenderModems();
+    } catch (e) {
+        list.innerHTML = `<p class="text-sm text-red-500 px-3 py-2">Load failed: ${_esc(e.message)}</p>`;
+    }
+}
+
+function _swapRenderModems() {
+    const q = document.getElementById('swap-modem-search').value.trim().toLowerCase();
+    const list = document.getElementById('swap-modem-list');
+    let items = _swap.all_modems;
+    if (q) {
+        items = items.filter(m => {
+            const hay = [(m.id||''), (m.hardware_model||''), (m.ip_address||'')].join(' ').toLowerCase();
+            return hay.includes(q);
+        });
+    }
+    if (items.length === 0) {
+        list.innerHTML = '<p class="text-sm text-gray-500 dark:text-gray-400 px-3 py-2">No modems available.</p>';
+        return;
+    }
+    list.innerHTML = items.map(m => {
+        const hw = m.hardware_model ? `<span class="text-xs text-gray-500 dark:text-gray-400">${_esc(m.hardware_model)}</span>` : '';
+        const ip = m.ip_address ? `<div class="text-xs text-gray-500 dark:text-gray-400 font-mono">${_esc(m.ip_address)}</div>` : '';
+        const badge = _badge(m.deployed);
+        return `<button onclick='swapPickModem(${JSON.stringify(m.id)})'
+            class="swap-modem-pick w-full text-left px-3 py-3 rounded-lg border border-gray-200 dark:border-gray-700 hover:border-seismo-orange transition-colors"
+            data-modem-id="${_esc(m.id)}">
+            <div class="flex items-center justify-between gap-2">
+                <span class="font-mono font-semibold text-gray-900 dark:text-white">${_esc(m.id)}</span>
+                <div class="flex items-center gap-2">
+                    ${badge}
+                    ${hw}
+                </div>
+            </div>
+            ${ip}
+        </button>`;
+    }).join('');
+}
+
+function swapPickModem(modemId) {
+    const m = _swap.all_modems.find(x => x.id === modemId);
+    if (!m) return;
+    _swap.new_modem = m;
+    document.querySelectorAll('.swap-modem-pick').forEach(btn => {
+        if (btn.dataset.modemId === modemId) {
+            btn.classList.add('border-seismo-orange', 'bg-amber-50', 'dark:bg-amber-900/10');
+        } else {
+            btn.classList.remove('border-seismo-orange', 'bg-amber-50', 'dark:bg-amber-900/10');
+        }
+    });
+    document.getElementById('swap-modem-next').disabled = false;
+}
+
+function swapAfterModem() {
+    // Populate review screen
+    document.getElementById('swap-review-project').textContent = _swap.project.name;
+    document.getElementById('swap-review-location').textContent = _swap.location.name;
+    document.getElementById('swap-review-old-unit').textContent = _swap.location.unit ? _swap.location.unit.id : '(empty)';
+    document.getElementById('swap-review-new-unit').textContent = _swap.new_unit.id;
+
+    const oldModemEl = document.getElementById('swap-review-old-modem');
+    if (_swap.location.modem) {
+        oldModemEl.innerHTML = `${_esc(_swap.location.modem.id)} ${_badge(_swap.location.modem.deployed)}`;
+    } else {
+        oldModemEl.textContent = '(none)';
+    }
+
+    const newModemEl = document.getElementById('swap-review-new-modem');
+    if (_swap.modem_action === 'keep' && _swap.location.modem) {
+        newModemEl.innerHTML = `${_esc(_swap.location.modem.id)} <span class="text-xs text-gray-500">(kept)</span> ${_badge(_swap.location.modem.deployed)}`;
+    } else if ((_swap.modem_action === 'swap' || _swap.modem_action === 'add') && _swap.new_modem) {
+        newModemEl.innerHTML = `${_esc(_swap.new_modem.id)} ${_badge(_swap.new_modem.deployed)}`;
+    } else {
+        newModemEl.textContent = '(none)';
+    }
+
+    swapGoToStep(5);
+}
+
+// ── Step 5: confirm ─────────────────────────────────────────────────
+async function swapConfirm() {
+    const btn = document.getElementById('swap-confirm-btn');
+    const err = document.getElementById('swap-error');
+    err.classList.add('hidden');
+
+    // Determine modem_id to send:
+    //   'keep'   → current modem id  (re-pair to new unit)
+    //   'swap'   → newly-picked modem id
+    //   'add'    → newly-picked modem id
+    //   'remove' → omit (endpoint clears new unit's pairing)
+    //   'none'   → omit
+    let modemIdToSend = null;
+    if (_swap.modem_action === 'keep' && _swap.location.modem) {
+        modemIdToSend = _swap.location.modem.id;
+    } else if ((_swap.modem_action === 'swap' || _swap.modem_action === 'add') && _swap.new_modem) {
+        modemIdToSend = _swap.new_modem.id;
+    }
+
+    btn.disabled = true;
+    btn.textContent = 'Swapping…';
+
+    const fd = new FormData();
+    fd.append('unit_id', _swap.new_unit.id);
+    if (modemIdToSend) fd.append('modem_id', modemIdToSend);
+    const notes = document.getElementById('swap-notes').value.trim();
+    if (notes) fd.append('notes', notes);
+
+    try {
+        const url = `/api/projects/${encodeURIComponent(_swap.project.id)}/locations/${encodeURIComponent(_swap.location.id)}/swap`;
+        const r = await fetch(url, { method: 'POST', body: fd });
+        if (!r.ok) {
+            const e = await r.json().catch(() => ({detail: 'HTTP ' + r.status}));
+            throw new Error(e.detail || 'HTTP ' + r.status);
+        }
+        _swap.swap_result = await r.json();
+        _swapShowDone();
+    } catch (e) {
+        err.textContent = e.message;
+        err.classList.remove('hidden');
+        btn.disabled = false;
+        btn.textContent = 'Confirm swap';
+    }
+}
+
+function _swapShowDone() {
+    for (let i = 1; i <= 5; i++) {
+        document.getElementById('swap-step-' + i).classList.add('hidden');
+    }
+    document.getElementById('swap-step-done').classList.remove('hidden');
+    const summary = `${_swap.new_unit.id} is now at ${_swap.location.name}` +
+        (_swap.location.unit ? ` (replacing ${_swap.location.unit.id}).` : '.');
+    document.getElementById('swap-done-summary').textContent = summary;
+}
+
+// ── Photo upload (optional) ─────────────────────────────────────────
+function swapOnPhotoPicked(e) {
+    const file = e.target.files && e.target.files[0];
+    if (!file) return;
+    _swap.photo_file = file;
+    if (_swap.photo_preview_url) URL.revokeObjectURL(_swap.photo_preview_url);
+    _swap.photo_preview_url = URL.createObjectURL(file);
+    document.getElementById('swap-photo-preview').src = _swap.photo_preview_url;
+    document.getElementById('swap-photo-preview-wrap').classList.remove('hidden');
+    document.getElementById('swap-photo-upload-btn').disabled = false;
+}
+
+async function swapUploadPhoto() {
+    if (!_swap.photo_file) return;
+    const btn = document.getElementById('swap-photo-upload-btn');
+    const err = document.getElementById('swap-photo-error');
+    const ok  = document.getElementById('swap-photo-status');
+    err.classList.add('hidden');
+    ok.classList.add('hidden');
+    btn.disabled = true;
+    btn.textContent = 'Uploading…';
+
+    const fd = new FormData();
+    fd.append('photo', _swap.photo_file);
+
+    try {
+        const url = `/api/unit/${encodeURIComponent(_swap.new_unit.id)}/upload-photo?auto_populate_coords=true`;
+        const r = await fetch(url, { method: 'POST', body: fd });
+        if (!r.ok) {
+            const e = await r.json().catch(() => ({detail: 'HTTP ' + r.status}));
+            throw new Error(e.detail || 'HTTP ' + r.status);
+        }
+        const data = await r.json();
+        const coords = data && data.metadata && data.metadata.coordinates;
+        ok.textContent = coords ? `Uploaded. GPS: ${coords}` : 'Uploaded (no GPS in EXIF).';
+        ok.classList.remove('hidden');
+        btn.textContent = 'Uploaded';
+    } catch (e) {
+        err.textContent = e.message;
+        err.classList.remove('hidden');
+        btn.disabled = false;
+        btn.textContent = 'Upload photo';
+    }
+}
+
+function swapReset() {
+    if (_swap.photo_preview_url) URL.revokeObjectURL(_swap.photo_preview_url);
+    Object.assign(_swap, {
+        project: null, location: null, new_unit: null,
+        modem_action: null, new_modem: null,
+        all_projects: [], all_units: [], all_modems: [],
+        swap_result: null, photo_file: null, photo_preview_url: null,
+    });
+    document.getElementById('swap-project-search').value = '';
+    document.getElementById('swap-unit-search').value = '';
+    document.getElementById('swap-modem-search').value = '';
+    document.getElementById('swap-notes').value = '';
+    document.getElementById('swap-photo-input').value = '';
+    document.getElementById('swap-photo-preview-wrap').classList.add('hidden');
+    document.getElementById('swap-photo-error').classList.add('hidden');
+    document.getElementById('swap-photo-status').classList.add('hidden');
+    document.getElementById('swap-error').classList.add('hidden');
+    const confirmBtn = document.getElementById('swap-confirm-btn');
+    confirmBtn.disabled = false; confirmBtn.textContent = 'Confirm swap';
+    const photoBtn = document.getElementById('swap-photo-upload-btn');
+    photoBtn.disabled = true; photoBtn.textContent = 'Upload photo';
+    swapGoToStep(1);
+    _swapLoadProjects();
+}
+
+// Wire up live filtering inputs.
+document.getElementById('swap-project-search').addEventListener('input', _swapRenderProjects);
+document.getElementById('swap-unit-search').addEventListener('input', _swapRenderUnits);
+document.getElementById('swap-modem-search').addEventListener('input', _swapRenderModems);
+
+// Kick off.
+_swapLoadProjects();
+</script>
+{% endblock %}

templates/base.html

@@ -150,6 +150,7 @@
                    (project tidy, metadata backfill, pair devices). #}
                 {% set _is_tools = (
                     request.url.path == '/tools'
+                    or request.url.path.startswith('/tools/')
                     or request.url.path == '/pair-devices'
                     or request.url.path == '/settings/developer/project-tidy'
                     or request.url.path == '/settings/developer/metadata-backfill'

templates/tools.html

@@ -141,6 +141,24 @@
         </div>
     </a>
 
+    <!-- Unit Swap -->
+    <a href="/tools/unit-swap"
+       class="block bg-white dark:bg-slate-800 rounded-xl shadow-lg p-5 hover:shadow-xl transition-shadow border border-transparent hover:border-seismo-orange">
+        <div class="flex items-start gap-3">
+            <div class="w-10 h-10 rounded-lg bg-amber-100 dark:bg-amber-900/30 text-amber-600 dark:text-amber-400 flex items-center justify-center shrink-0">
+                <svg class="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M7 16V4m0 0L3 8m4-4l4 4m6 0v12m0 0l4-4m-4 4l-4-4"/>
+                </svg>
+            </div>
+            <div class="flex-1 min-w-0">
+                <h3 class="font-semibold text-gray-900 dark:text-white">Unit Swap</h3>
+                <p class="text-sm text-gray-600 dark:text-gray-400 mt-1">
+                    Field-swap a unit (and modem) at a vibration location. Pick project → location → incoming unit → confirm. Optional photo of the new install.
+                </p>
+            </div>
+        </div>
+    </a>
+
     <!-- Swap Detection (Phase 5c — coming soon) -->
     <div class="bg-gray-50 dark:bg-slate-800/50 rounded-xl shadow p-5 border border-dashed border-gray-300 dark:border-gray-700 cursor-not-allowed">
         <div class="flex items-start gap-3">

templates/unit_detail.html

@@ -281,11 +281,16 @@
             <!-- Deployment Timeline (Phase 4 unified view — derived from
                  unit_assignments + unit_history + SFM event overlay) -->
             <div class="border-t border-gray-200 dark:border-gray-700 pt-6">
-                <div class="flex justify-between items-center mb-4">
+                <div class="flex justify-between items-center mb-4 flex-wrap gap-2">
                     <h3 class="text-lg font-semibold text-gray-900 dark:text-white">Deployment Timeline</h3>
-                    <button onclick="loadDeploymentTimeline()" class="px-3 py-1.5 text-sm rounded-lg border border-gray-300 dark:border-gray-600 hover:bg-gray-50 dark:hover:bg-gray-700 text-gray-700 dark:text-gray-300">
+                    <div class="flex items-center gap-2">
-                        ↻ Refresh
+                        <button onclick="openAddAssignmentModal()" class="px-3 py-1.5 text-sm rounded-lg bg-seismo-orange hover:bg-orange-600 text-white">
-                    </button>
+                            + Add deployment record
+                        </button>
+                        <button onclick="loadDeploymentTimeline()" class="px-3 py-1.5 text-sm rounded-lg border border-gray-300 dark:border-gray-600 hover:bg-gray-50 dark:hover:bg-gray-700 text-gray-700 dark:text-gray-300">
+                            ↻ Refresh
+                        </button>
+                    </div>
                 </div>
 
                 <!-- Gantt chart — visual timeline of all deployments.  Click
@@ -302,6 +307,119 @@
                 </div>
             </div>
 
+            <!-- Edit-assignment modal -->
+            <div id="editAssignmentModal" class="hidden fixed inset-0 bg-black/60 z-50 flex items-center justify-center p-4">
+                <div class="bg-white dark:bg-slate-800 rounded-xl shadow-2xl w-full max-w-md max-h-[90vh] overflow-y-auto">
+                    <div class="sticky top-0 bg-white dark:bg-slate-800 border-b border-gray-200 dark:border-gray-700 px-5 py-4 flex items-center justify-between">
+                        <h3 class="text-lg font-semibold text-gray-900 dark:text-white">Edit deployment record</h3>
+                        <button onclick="closeEditAssignmentModal()" class="text-2xl text-gray-500 hover:text-gray-700 dark:hover:text-gray-300">&times;</button>
+                    </div>
+                    <div class="p-5 space-y-4">
+                        <div class="text-sm text-gray-500 dark:text-gray-400">
+                            <span id="editAssignmentLocation">—</span>
+                            <span class="text-xs">·</span>
+                            <span id="editAssignmentProject" class="text-xs">—</span>
+                        </div>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Assigned at</span>
+                            <input id="editAssignedAt" type="datetime-local" step="60"
+                                   class="mt-1 w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+                        </label>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Assigned until</span>
+                            <div class="mt-1 flex items-center gap-2">
+                                <input id="editAssignedUntil" type="datetime-local" step="60"
+                                       class="flex-1 px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+                                <label class="inline-flex items-center gap-1 text-xs text-gray-700 dark:text-gray-300 whitespace-nowrap">
+                                    <input id="editAssignedUntilOpen" type="checkbox" onchange="_toggleEditOpenEnded()">
+                                    open-ended
+                                </label>
+                            </div>
+                            <p class="text-xs text-gray-500 dark:text-gray-400 mt-1">Check "open-ended" to mark this assignment active (no end date).</p>
+                        </label>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Notes</span>
+                            <textarea id="editAssignmentNotes" rows="2"
+                                      class="mt-1 w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white"></textarea>
+                        </label>
+                        <div id="editAssignmentError" class="hidden text-sm text-red-600"></div>
+                    </div>
+                    <div class="sticky bottom-0 bg-white dark:bg-slate-800 border-t border-gray-200 dark:border-gray-700 px-5 py-3 flex items-center justify-between gap-2">
+                        <button onclick="deleteAssignmentFromModal()" class="px-3 py-2 text-sm rounded-lg border border-red-300 text-red-700 dark:border-red-700 dark:text-red-300 hover:bg-red-50 dark:hover:bg-red-900/20">
+                            Delete
+                        </button>
+                        <div class="flex gap-2">
+                            <button onclick="closeEditAssignmentModal()" class="px-4 py-2 text-sm rounded-lg border border-gray-300 dark:border-gray-600 text-gray-700 dark:text-gray-300 hover:bg-gray-50 dark:hover:bg-gray-700">
+                                Cancel
+                            </button>
+                            <button id="editAssignmentSaveBtn" onclick="saveEditAssignment()" class="px-4 py-2 text-sm rounded-lg bg-seismo-orange hover:bg-orange-600 text-white">
+                                Save
+                            </button>
+                        </div>
+                    </div>
+                </div>
+            </div>
+
+            <!-- Add-historical-assignment modal -->
+            <div id="addAssignmentModal" class="hidden fixed inset-0 bg-black/60 z-50 flex items-center justify-center p-4">
+                <div class="bg-white dark:bg-slate-800 rounded-xl shadow-2xl w-full max-w-md max-h-[90vh] overflow-y-auto">
+                    <div class="sticky top-0 bg-white dark:bg-slate-800 border-b border-gray-200 dark:border-gray-700 px-5 py-4 flex items-center justify-between">
+                        <h3 class="text-lg font-semibold text-gray-900 dark:text-white">Add deployment record</h3>
+                        <button onclick="closeAddAssignmentModal()" class="text-2xl text-gray-500 hover:text-gray-700 dark:hover:text-gray-300">&times;</button>
+                    </div>
+                    <div class="p-5 space-y-4">
+                        <p class="text-xs text-gray-500 dark:text-gray-400">
+                            Create a deployment record for this unit — usually to backfill a historical window so orphan events get attributed.
+                        </p>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Project</span>
+                            <select id="addAssignmentProject" onchange="_addAssignmentProjectChanged()"
+                                    class="mt-1 w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+                                <option value="">Loading…</option>
+                            </select>
+                        </label>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Location</span>
+                            <select id="addAssignmentLocation"
+                                    class="mt-1 w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white" disabled>
+                                <option value="">Pick a project first</option>
+                            </select>
+                        </label>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Assigned at</span>
+                            <input id="addAssignedAt" type="datetime-local" step="60"
+                                   class="mt-1 w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+                        </label>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Assigned until</span>
+                            <div class="mt-1 flex items-center gap-2">
+                                <input id="addAssignedUntil" type="datetime-local" step="60"
+                                       class="flex-1 px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white">
+                                <label class="inline-flex items-center gap-1 text-xs text-gray-700 dark:text-gray-300 whitespace-nowrap">
+                                    <input id="addAssignedUntilOpen" type="checkbox" onchange="_toggleAddOpenEnded()">
+                                    open-ended
+                                </label>
+                            </div>
+                        </label>
+                        <label class="block">
+                            <span class="text-sm font-medium text-gray-700 dark:text-gray-300">Notes</span>
+                            <textarea id="addAssignmentNotes" rows="2"
+                                      placeholder="e.g. Backfilled to attribute orphan events 2026-03-16 — 2026-03-25"
+                                      class="mt-1 w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-slate-700 text-gray-900 dark:text-white"></textarea>
+                        </label>
+                        <div id="addAssignmentError" class="hidden text-sm text-red-600"></div>
+                    </div>
+                    <div class="sticky bottom-0 bg-white dark:bg-slate-800 border-t border-gray-200 dark:border-gray-700 px-5 py-3 flex justify-end gap-2">
+                        <button onclick="closeAddAssignmentModal()" class="px-4 py-2 text-sm rounded-lg border border-gray-300 dark:border-gray-600 text-gray-700 dark:text-gray-300 hover:bg-gray-50 dark:hover:bg-gray-700">
+                            Cancel
+                        </button>
+                        <button id="addAssignmentSaveBtn" onclick="saveAddAssignment()" class="px-4 py-2 text-sm rounded-lg bg-seismo-orange hover:bg-orange-600 text-white">
+                            Create
+                        </button>
+                    </div>
+                </div>
+            </div>
+
             <!-- SFM Events (seismographs only) -->
             <div id="sfmEventsSection" class="border-t border-gray-200 dark:border-gray-700 pt-6 hidden">
                 <div class="flex justify-between items-center mb-4">
@@ -2141,6 +2259,16 @@ function _dtRenderAssignment(e) {
         ? `<div class="mt-2 text-xs text-gray-600 dark:text-gray-400 italic">${_dtEsc(e.notes)}</div>`
         : '';
 
+    // Edit/delete actions live on the right of the date row.  Only shown
+    // for assignment entries with a real assignment_id (synthesized legacy
+    // entries without one are read-only).
+    const actionButtons = e.assignment_id
+        ? `<button type="button" onclick='openEditAssignmentModal(${JSON.stringify(e.assignment_id)})'
+              class="text-xs text-gray-500 hover:text-seismo-orange p-1 rounded" title="Edit dates / notes">
+              ✏️
+           </button>`
+        : '';
+
     return `<div class="flex gap-3 transition-shadow rounded-lg" data-assignment-row="${_dtEsc(e.assignment_id)}">
         <div class="flex flex-col items-center pt-1">
             <span class="w-3 h-3 rounded-full ${e.is_active ? 'bg-green-500' : 'bg-seismo-orange'}"></span>
@@ -2153,6 +2281,7 @@ function _dtRenderAssignment(e) {
                 <div class="flex items-center gap-2">
                     ${mergeableBadge}
                     ${activeBadge}
+                    ${actionButtons}
                 </div>
             </div>
             <div class="mt-1">${locLink}</div>
@@ -2455,6 +2584,261 @@ function renderDeploymentTimeline(entries, container, mergeGroups) {
     container.innerHTML = bannerHtml + '<div class="space-y-3">' + html + '</div>';
 }
 
+// ── Deployment-timeline editor ──────────────────────────────────────────────
+// Edit / delete an existing UnitAssignment row, or create a historical one
+// (backfill orphan-event windows).  All three operations hit endpoints that
+// already exist on the project-locations router; after a save we just
+// reload the timeline + events.
+
+let _editAssignmentCtx = null;   // { assignment_id, project_id, location_name, project_name }
+
+function _iso_to_local_input(iso) {
+    // The PATCH/POST endpoints accept "YYYY-MM-DDTHH:MM[:SS]" strings
+    // (datetime.fromisoformat).  datetime-local inputs emit the same shape
+    // without timezone.  We just strip the trailing "Z" if present and
+    // truncate to minutes.
+    if (!iso) return '';
+    let s = String(iso).replace('Z', '');
+    // Slice down to YYYY-MM-DDTHH:MM (16 chars).
+    return s.slice(0, 16);
+}
+
+function openEditAssignmentModal(assignmentId) {
+    const entry = (_dtCurrentTimeline.entries || []).find(
+        e => e.kind === 'assignment' && e.assignment_id === assignmentId
+    );
+    if (!entry) {
+        alert('Could not find this assignment in the loaded timeline.');
+        return;
+    }
+    _editAssignmentCtx = {
+        assignment_id:  entry.assignment_id,
+        project_id:     entry.project_id,
+        location_name:  entry.location_name || 'unnamed location',
+        project_name:   entry.project_name  || '',
+    };
+
+    document.getElementById('editAssignmentLocation').textContent = _editAssignmentCtx.location_name;
+    document.getElementById('editAssignmentProject').textContent  = _editAssignmentCtx.project_name;
+
+    document.getElementById('editAssignedAt').value    = _iso_to_local_input(entry.starts_at);
+    const endsAtInput  = document.getElementById('editAssignedUntil');
+    const openCheckbox = document.getElementById('editAssignedUntilOpen');
+    if (entry.is_active) {
+        endsAtInput.value = '';
+        endsAtInput.disabled = true;
+        openCheckbox.checked = true;
+    } else {
+        endsAtInput.value = _iso_to_local_input(entry.ends_at);
+        endsAtInput.disabled = false;
+        openCheckbox.checked = false;
+    }
+    document.getElementById('editAssignmentNotes').value = entry.notes || '';
+    document.getElementById('editAssignmentError').classList.add('hidden');
+    document.getElementById('editAssignmentModal').classList.remove('hidden');
+}
+
+function closeEditAssignmentModal() {
+    document.getElementById('editAssignmentModal').classList.add('hidden');
+    _editAssignmentCtx = null;
+}
+
+function _toggleEditOpenEnded() {
+    const open  = document.getElementById('editAssignedUntilOpen').checked;
+    const input = document.getElementById('editAssignedUntil');
+    input.disabled = open;
+    if (open) input.value = '';
+}
+
+async function saveEditAssignment() {
+    if (!_editAssignmentCtx) return;
+    const err = document.getElementById('editAssignmentError');
+    err.classList.add('hidden');
+
+    const assignedAt = document.getElementById('editAssignedAt').value;
+    if (!assignedAt) {
+        err.textContent = 'Assigned-at is required.';
+        err.classList.remove('hidden');
+        return;
+    }
+    const open        = document.getElementById('editAssignedUntilOpen').checked;
+    const assignedUntil = open ? null : (document.getElementById('editAssignedUntil').value || null);
+    const notes       = document.getElementById('editAssignmentNotes').value;
+
+    const btn = document.getElementById('editAssignmentSaveBtn');
+    btn.disabled = true; btn.textContent = 'Saving…';
+
+    try {
+        const url = `/api/projects/${encodeURIComponent(_editAssignmentCtx.project_id)}/assignments/${encodeURIComponent(_editAssignmentCtx.assignment_id)}`;
+        const r = await fetch(url, {
+            method:  'PATCH',
+            headers: { 'Content-Type': 'application/json' },
+            body:    JSON.stringify({
+                assigned_at:    assignedAt,
+                assigned_until: assignedUntil,
+                notes:          notes,
+            }),
+        });
+        if (!r.ok) {
+            const e = await r.json().catch(() => ({detail: 'HTTP ' + r.status}));
+            throw new Error(e.detail || 'HTTP ' + r.status);
+        }
+        closeEditAssignmentModal();
+        await loadDeploymentTimeline();
+        if (typeof loadUnitEvents === 'function' && currentUnit && currentUnit.device_type === 'seismograph') {
+            loadUnitEvents();
+        }
+    } catch (e) {
+        err.textContent = e.message;
+        err.classList.remove('hidden');
+    } finally {
+        btn.disabled = false; btn.textContent = 'Save';
+    }
+}
+
+async function deleteAssignmentFromModal() {
+    if (!_editAssignmentCtx) return;
+    if (!confirm('Hard-delete this deployment record?\n\nThe assignment row and its history audit entry are removed.  Use this only for misclicks — to end a real deployment, edit the "assigned until" date instead.')) return;
+    const err = document.getElementById('editAssignmentError');
+    err.classList.add('hidden');
+    try {
+        const url = `/api/projects/${encodeURIComponent(_editAssignmentCtx.project_id)}/assignments/${encodeURIComponent(_editAssignmentCtx.assignment_id)}`;
+        const r = await fetch(url, { method: 'DELETE' });
+        if (!r.ok) {
+            const e = await r.json().catch(() => ({detail: 'HTTP ' + r.status}));
+            throw new Error(e.detail || 'HTTP ' + r.status);
+        }
+        closeEditAssignmentModal();
+        await loadDeploymentTimeline();
+        if (typeof loadUnitEvents === 'function' && currentUnit && currentUnit.device_type === 'seismograph') {
+            loadUnitEvents();
+        }
+    } catch (e) {
+        err.textContent = e.message;
+        err.classList.remove('hidden');
+    }
+}
+
+// ── Add-historical-assignment modal ─────────────────────────────────────────
+let _addAssignmentProjectsCache = null;
+
+async function openAddAssignmentModal() {
+    if (!currentUnit) return;
+    document.getElementById('addAssignmentError').classList.add('hidden');
+    document.getElementById('addAssignedAt').value    = '';
+    document.getElementById('addAssignedUntil').value = '';
+    document.getElementById('addAssignedUntilOpen').checked = false;
+    document.getElementById('addAssignedUntil').disabled    = false;
+    document.getElementById('addAssignmentNotes').value     = '';
+
+    const locSel = document.getElementById('addAssignmentLocation');
+    locSel.disabled = true;
+    locSel.innerHTML = '<option value="">Pick a project first</option>';
+
+    const projSel = document.getElementById('addAssignmentProject');
+    projSel.innerHTML = '<option value="">Loading…</option>';
+
+    document.getElementById('addAssignmentModal').classList.remove('hidden');
+
+    try {
+        if (!_addAssignmentProjectsCache) {
+            const r = await fetch('/api/projects/search-json?limit=50');
+            if (!r.ok) throw new Error('HTTP ' + r.status);
+            _addAssignmentProjectsCache = await r.json();
+        }
+        projSel.innerHTML = '<option value="">— pick project —</option>'
+            + _addAssignmentProjectsCache.map(p =>
+                `<option value="${_dtEsc(p.id)}">${_dtEsc(p.name)}${p.project_number ? ' (' + _dtEsc(p.project_number) + ')' : ''}</option>`
+            ).join('');
+    } catch (e) {
+        projSel.innerHTML = `<option value="">Load failed: ${_dtEsc(e.message)}</option>`;
+    }
+}
+
+function closeAddAssignmentModal() {
+    document.getElementById('addAssignmentModal').classList.add('hidden');
+}
+
+function _toggleAddOpenEnded() {
+    const open  = document.getElementById('addAssignedUntilOpen').checked;
+    const input = document.getElementById('addAssignedUntil');
+    input.disabled = open;
+    if (open) input.value = '';
+}
+
+async function _addAssignmentProjectChanged() {
+    const projectId = document.getElementById('addAssignmentProject').value;
+    const locSel = document.getElementById('addAssignmentLocation');
+    if (!projectId) {
+        locSel.disabled = true;
+        locSel.innerHTML = '<option value="">Pick a project first</option>';
+        return;
+    }
+    locSel.disabled = true;
+    locSel.innerHTML = '<option value="">Loading locations…</option>';
+    // Match the device type to the location_type filter.
+    const wantType = (currentUnit && currentUnit.device_type === 'slm') ? 'sound' : 'vibration';
+    try {
+        const r = await fetch(`/api/projects/${encodeURIComponent(projectId)}/locations-json?location_type=${wantType}`);
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        const locs = await r.json();
+        if (!locs.length) {
+            locSel.innerHTML = '<option value="">No matching locations in this project</option>';
+            return;
+        }
+        locSel.disabled = false;
+        locSel.innerHTML = '<option value="">— pick location —</option>'
+            + locs.map(l => `<option value="${_dtEsc(l.id)}">${_dtEsc(l.name)}</option>`).join('');
+    } catch (e) {
+        locSel.innerHTML = `<option value="">Load failed: ${_dtEsc(e.message)}</option>`;
+    }
+}
+
+async function saveAddAssignment() {
+    if (!currentUnit) return;
+    const err = document.getElementById('addAssignmentError');
+    err.classList.add('hidden');
+
+    const projectId  = document.getElementById('addAssignmentProject').value;
+    const locationId = document.getElementById('addAssignmentLocation').value;
+    const assignedAt = document.getElementById('addAssignedAt').value;
+    const open       = document.getElementById('addAssignedUntilOpen').checked;
+    const assignedUntil = open ? '' : document.getElementById('addAssignedUntil').value;
+    const notes      = document.getElementById('addAssignmentNotes').value;
+
+    if (!projectId)  { err.textContent = 'Pick a project.';  err.classList.remove('hidden'); return; }
+    if (!locationId) { err.textContent = 'Pick a location.'; err.classList.remove('hidden'); return; }
+    if (!assignedAt) { err.textContent = 'Assigned-at is required.'; err.classList.remove('hidden'); return; }
+
+    const btn = document.getElementById('addAssignmentSaveBtn');
+    btn.disabled = true; btn.textContent = 'Creating…';
+
+    try {
+        const fd = new FormData();
+        fd.append('unit_id',     currentUnit.id);
+        fd.append('assigned_at', assignedAt);
+        if (assignedUntil) fd.append('assigned_until', assignedUntil);
+        if (notes)         fd.append('notes',          notes);
+
+        const url = `/api/projects/${encodeURIComponent(projectId)}/locations/${encodeURIComponent(locationId)}/assign`;
+        const r = await fetch(url, { method: 'POST', body: fd });
+        if (!r.ok) {
+            const e = await r.json().catch(() => ({detail: 'HTTP ' + r.status}));
+            throw new Error(e.detail || 'HTTP ' + r.status);
+        }
+        closeAddAssignmentModal();
+        await loadDeploymentTimeline();
+        if (typeof loadUnitEvents === 'function' && currentUnit.device_type === 'seismograph') {
+            loadUnitEvents();
+        }
+    } catch (e) {
+        err.textContent = e.message;
+        err.classList.remove('hidden');
+    } finally {
+        btn.disabled = false; btn.textContent = 'Create';
+    }
+}
+
 // ── SFM Events section ──────────────────────────────────────────────────────
 function clearUnitEventFilters() {
     document.getElementById('ue-filter-bucket').value = 'all';