diff --git a/CHANGELOG.md b/CHANGELOG.md
index cfe0043..bd3d0df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,65 @@ All notable changes to Seismo Fleet Manager 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).
 
+## [0.3.0] - 2025-12-09
+
+### Added
+- **Series 4 (Micromate) Support**: New `/api/series4/heartbeat` endpoint for receiving telemetry from Series 4 Micromate units
+  - Auto-detection of Series 4 units via UM##### ID pattern
+  - Stores project hints from emitter payload in unit notes
+  - Automatic unit type classification across both Series 3 and Series 4 endpoints
+- **Development Environment Labels**: Visual indicators to distinguish dev from production deployments
+  - Yellow "DEV" badge in sidebar navigation
+  - "[DEV]" prefix in browser title
+  - Yellow banner on dashboard when running in development mode
+  - Environment variable support in docker-compose.yml (ENVIRONMENT=production|development)
+- **Quality of Life Improvements**:
+  - Human-readable relative timestamps (e.g., "2h 15m ago", "3d ago") with full date in tooltips
+  - "Last Updated" timestamp indicator on dashboard
+  - Status icons for colorblind accessibility (checkmark for OK, clock for Pending, X for Missing)
+  - Breadcrumb navigation on unit detail pages
+  - Copy-to-clipboard buttons for unit IDs
+  - Search/filter functionality for fleet roster table
+  - Improved empty state messages with icons
+- **Timezone Support**: Comprehensive timezone handling across the application
+  - Timezone selector in Settings (defaults to America/New_York EST)
+  - Human-readable timestamp format (e.g., "9/10/2020 8:00 AM EST")
+  - Timezone-aware display for all timestamps site-wide
+  - Settings stored in localStorage for immediate effect
+- **Settings Page Redesign**: Complete overhaul with tabbed interface and persistent preferences
+  - **General Tab**: Display preferences (timezone, theme, auto-refresh interval)
+  - **Data Management Tab**: Safe operations (CSV export, merge import, roster table)
+  - **Advanced Tab**: Power user settings (replace mode import, calibration defaults, status thresholds)
+  - **Danger Zone Tab**: Destructive operations isolated with enhanced warnings
+  - Backend preferences storage via new UserPreferences model
+  - Tab state persistence in localStorage
+  - Smooth animations and consistent styling with existing pages
+- **User Preferences API**: New backend endpoints for persistent settings storage
+  - `GET /api/settings/preferences` - Retrieve all user preferences
+  - `PUT /api/settings/preferences` - Update preferences (supports partial updates)
+  - Database-backed storage for cross-device preference sync
+  - Migration script: `backend/migrate_add_user_preferences.py`
+
+### Changed
+- Timestamps now display in user-selected timezone with human-readable format throughout the application
+- Settings page reorganized from 644-line flat layout to clean 4-tab interface
+- CSV Replace Mode moved from Data Management to Advanced tab with additional warnings
+- Import operations separated: safe merge in Data Management tab, destructive replace in Advanced tab
+- Page title changed from "Roster Manager" to "Settings" for better clarity
+- All preferences now persist to backend database instead of relying solely on localStorage
+
+### Fixed
+- Unit type classification now consistent across Series 3 and Series 4 heartbeat endpoints
+- Auto-correction of misclassified unit types when they report to wrong endpoint
+
+### Technical Details
+- New `detect_unit_type()` helper function for pattern-based unit classification
+- UserPreferences model with single-row table pattern (id=1) for global settings
+- Series 4 units identified by UM prefix followed by digits (e.g., UM11719)
+- JavaScript Intl API used for client-side timezone conversion
+- Pydantic schema for partial preference updates (PreferencesUpdate model)
+- Environment context injection via custom FastAPI template response wrapper
+
 ## [0.2.1] - 2025-12-03
 
 ### Added
@@ -92,6 +151,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Photo management per unit
 - Automated status categorization (OK/Pending/Missing)
 
+[0.3.0]: https://github.com/serversdwn/seismo-fleet-manager/compare/v0.2.1...v0.3.0
 [0.2.1]: https://github.com/serversdwn/seismo-fleet-manager/compare/v0.2.0...v0.2.1
 [0.2.0]: https://github.com/serversdwn/seismo-fleet-manager/compare/v0.1.1...v0.2.0
 [0.1.1]: https://github.com/serversdwn/seismo-fleet-manager/compare/v0.1.0...v0.1.1
diff --git a/README.md b/README.md
index 5bc60c8..bb47f1c 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Seismo Fleet Manager v0.2.1
+# Seismo Fleet Manager v0.3.0
 
 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.
 
@@ -100,15 +100,27 @@ cp /tmp/sfm_test.db data/seismo_fleet.db
 
 The helper script creates a modem/seismograph mix so you can exercise the dashboard, roster tabs, and unit detail screens immediately.
 
-## Upgrading from v0.1.x
+## Upgrading from Previous Versions
 
-Versions ≥0.2 introduce new roster columns (device_type, calibration dates, modem metadata, addresses, etc.). Run the migration once per database file before starting the app:
+### From v0.2.x to v0.3.0
+
+Version 0.3.0 introduces user preferences storage. Run the migration once per database file:
+
+```bash
+python backend/migrate_add_user_preferences.py
+```
+
+This creates the `user_preferences` table for persistent settings storage (timezone, theme, auto-refresh interval, calibration defaults, status thresholds).
+
+### From v0.1.x to v0.2.x or later
+
+Versions ≥0.2 introduce new roster columns (device_type, calibration dates, modem metadata, addresses, etc.). Run the migration once per database file:
 
 ```bash
 python backend/migrate_add_device_types.py
 ```
 
-The script is idempotent—if the new columns already exist it simply exits.
+Both migration scripts are idempotent—if the columns/tables already exist, they simply exit.
 
 ## API Endpoints
 
@@ -156,6 +168,8 @@ The script is idempotent—if the new columns already exist it simply exits.
 - **GET** `/api/settings/stats` - Counts for roster, emitters, and ignored tables
 - **GET** `/api/settings/roster-units` - Raw roster dump for the settings data grid
 - **POST** `/api/settings/import-csv-replace` - Replace the entire roster in one atomic transaction
+- **GET** `/api/settings/preferences` - Get user preferences (timezone, theme, calibration defaults, etc.)
+- **PUT** `/api/settings/preferences` - Update user preferences (supports partial updates)
 - **POST** `/api/settings/clear-all` - Danger-zone action that wipes roster, emitters, and ignored tables
 - **POST** `/api/settings/clear-roster` - Delete only roster entries
 - **POST** `/api/settings/clear-emitters` - Delete auto-discovered emitters
@@ -182,7 +196,8 @@ See [sample_roster.csv](sample_roster.csv) for a minimal working example.
 
 ### Emitter Reporting
 - **POST** `/emitters/report` - Submit status report from a seismograph unit
-- **POST** `/api/series3/heartbeat` - Series3 multi-unit telemetry payload
+- **POST** `/api/series3/heartbeat` - Series 3 multi-unit telemetry payload
+- **POST** `/api/series4/heartbeat` - Series 4 (Micromate) multi-unit telemetry payload
 - **GET** `/fleet/status` - Retrieve status of all seismograph units (legacy)
 
 ### Photo Management
@@ -314,6 +329,22 @@ print(response.json())
 | reason | string | Optional context for ignoring |
 | ignored_at | datetime | When the ignore action occurred |
 
+### UserPreferences Table (Settings Storage)
+
+| Field | Type | Description |
+|-------|------|-------------|
+| id | integer | Always 1 (single-row table) |
+| timezone | string | Display timezone (default: America/New_York) |
+| theme | string | UI theme: auto, light, or dark |
+| auto_refresh_interval | integer | Dashboard refresh interval in seconds |
+| date_format | string | Date format preference |
+| table_rows_per_page | integer | Default pagination size |
+| calibration_interval_days | integer | Default days between calibrations |
+| calibration_warning_days | integer | Warning threshold before calibration due |
+| status_ok_threshold_hours | integer | Hours for OK status threshold |
+| status_pending_threshold_hours | integer | Hours for Pending status threshold |
+| updated_at | datetime | Last preference update timestamp |
+
 ## Project Structure
 
 ```
@@ -321,8 +352,8 @@ seismo-fleet-manager/
 ├── backend/
 │   ├── main.py              # FastAPI app entry point
 │   ├── database.py          # SQLAlchemy database configuration
-│   ├── models.py            # Database models (RosterUnit, Emitter, IgnoredUnit)
-│   ├── routes.py            # Legacy API endpoints
+│   ├── models.py            # Database models (RosterUnit, Emitter, IgnoredUnit, UserPreferences)
+│   ├── routes.py            # Legacy API endpoints + Series 3/4 heartbeat endpoints
 │   ├── routers/             # Modular API routers
 │   │   ├── roster.py        # Fleet status endpoints
 │   │   ├── roster_edit.py   # Roster management & CSV import
@@ -330,10 +361,11 @@ seismo-fleet-manager/
 │   │   ├── photos.py        # Photo management
 │   │   ├── dashboard.py     # Dashboard partials
 │   │   ├── dashboard_tabs.py # Dashboard tab endpoints
-│   │   └── settings.py      # Roster manager/data operations
+│   │   └── settings.py      # Settings, preferences, and data management
 │   ├── services/
 │   │   └── snapshot.py      # Fleet status snapshot logic
 │   ├── migrate_add_device_types.py # SQLite migration for v0.2 schema
+│   ├── migrate_add_user_preferences.py # SQLite migration for v0.3 schema
 │   └── static/              # Static assets (CSS, etc.)
 ├── create_test_db.py        # Generate a sample SQLite DB with mixed devices
 ├── templates/               # Jinja2 HTML templates
@@ -400,24 +432,31 @@ docker compose down -v
 
 ## Release Highlights
 
+### v0.3.0 — 2025-12-09
+- **Series 4 Support**: New `/api/series4/heartbeat` endpoint with auto-detection for Micromate units (UM##### pattern)
+- **Settings Redesign**: Completely redesigned Settings page with 4-tab interface (General, Data Management, Advanced, Danger Zone)
+- **User Preferences**: Backend storage for timezone, theme, auto-refresh interval, calibration defaults, and status thresholds
+- **Development Labels**: Visual indicators to distinguish dev from production environments
+- **Timezone Support**: Comprehensive timezone handling with human-readable timestamps site-wide
+- **Quality of Life**: Relative timestamps, status icons for accessibility, breadcrumb navigation, copy-to-clipboard, search functionality
+
 ### v0.2.1 — 2025-12-03
-- Added the `/settings` roster manager with CSV export/import, live stats, and danger-zone table reset actions.
-- Deployed/Benched/Retired/Ignored tabs now have dedicated HTMX partials, sorting, and inline actions (edit, deploy toggle, ignore, delete).
-- Unit detail pages expose device-type specific metadata (calibration windows, modem pairing, IP/phone fields) with a refreshed editing experience.
-- Snapshot summary and dashboard counts now focus on deployed units and include address/coordinate data for mapping widgets.
+- Added the `/settings` roster manager with CSV export/import, live stats, and danger-zone table reset actions
+- Deployed/Benched/Retired/Ignored tabs now have dedicated HTMX partials, sorting, and inline actions
+- Unit detail pages expose device-type specific metadata (calibration windows, modem pairing, IP/phone fields)
+- Snapshot summary and dashboard counts now focus on deployed units and include address/coordinate data
 
 ### v0.2.0 — 2025-12-03
-- Introduced device-type aware roster schema (seismograph vs modem) plus migration + `create_test_db.py` helper for new installs.
-- Added Ignore list model/endpoints to quarantine noisy emitters directly from the roster.
-- Roster page gained Add Unit + CSV Import modals, HTMX-driven updates, and unknown emitter callouts.
-- Snapshot service now returns active/benched/retired/unknown buckets containing richer metadata for the dashboard and roster tabs.
+- Introduced device-type aware roster schema (seismograph vs modem) plus migration + `create_test_db.py` helper
+- Added Ignore list model/endpoints to quarantine noisy emitters directly from the roster
+- Roster page gained Add Unit + CSV Import modals, HTMX-driven updates, and unknown emitter callouts
+- Snapshot service now returns active/benched/retired/unknown buckets containing richer metadata
 
 ### v0.1.1 — 2025-12-02
 - **Roster Editing API**: Full CRUD operations for managing your fleet roster
 - **CSV Import**: Bulk upload roster data from CSV files
 - **Enhanced Data Model**: Added project_id and location fields to roster
 - **Bug Fixes**: Improved database session management and error handling
-- **Dashboard Improvements**: Separate views for Active, Benched, and Retired units
 
 See [CHANGELOG.md](CHANGELOG.md) for the full release notes.
 
@@ -437,9 +476,11 @@ MIT
 
 ## Version
 
-**Current: 0.2.1** — Settings & roster manager refresh (2025-12-03)
+**Current: 0.3.0** — Series 4 support, settings redesign, user preferences (2025-12-09)
 
-Previous: 0.2.0 — Device-type aware roster + ignore list (2025-12-03)
+Previous: 0.2.1 — Settings & roster manager refresh (2025-12-03)
+
+0.2.0 — Device-type aware roster + ignore list (2025-12-03)
 
 0.1.1 — Roster Management & CSV Import (2025-12-02)
 
diff --git a/backend/main.py b/backend/main.py
index 4ca8828..d707063 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -18,7 +18,7 @@ Base.metadata.create_all(bind=engine)
 ENVIRONMENT = os.getenv("ENVIRONMENT", "production")
 
 # Initialize FastAPI app
-VERSION = "0.2.3"
+VERSION = "0.3.0"
 app = FastAPI(
     title="Seismo Fleet Manager",
     description="Backend API for managing seismograph fleet status",
@@ -258,9 +258,9 @@ async def unknown_emitters_partial(request: Request):
 def health_check():
     """Health check endpoint"""
     return {
-        "message": "Seismo Fleet Manager v0.1.1",
+        "message": f"Seismo Fleet Manager v{VERSION}",
         "status": "running",
-        "version": "0.1.1"
+        "version": VERSION
     }