diff --git a/docs/CONSUMER-INTEGRATION.md b/docs/CONSUMER-INTEGRATION.md
index 70036b8..009741a 100644
--- a/docs/CONSUMER-INTEGRATION.md
+++ b/docs/CONSUMER-INTEGRATION.md
@@ -296,6 +296,36 @@ ground-survey workflows.
   archive is at `https://firms.modaps.eosdis.nasa.gov/`.)
 - **Removal semantics:** none. FIRMS publishes detections; absence is the signal
   if a fire stops burning. Consumers should not expect explicit "removal" events.
+- **Enrichment (`data._enriched.geocoder`):** FIRMS is the enrichment pilot, so
+  each event carries a Central-derived geocoder bundle under
+  `data._enriched.geocoder`. It is *not* an upstream FIRMS field — Central
+  reverse-geocodes the hotspot's `latitude`/`longitude` and attaches the result.
+  The bundle always has these nine keys (any unresolved field is `null`, never
+  missing):
+
+  | key | meaning |
+  |---|---|
+  | `name` | place / feature name |
+  | `city` | city / town / village |
+  | `county` | county (or equivalent) |
+  | `state` | state / province |
+  | `country` | country |
+  | `postal_code` | postal / ZIP code |
+  | `timezone` | IANA tz (e.g. `America/Boise`) |
+  | `landclass` | land-management class (US PAD-US) |
+  | `elevation_m` | ground elevation, metres |
+
+  **Coverage by region (v0.5.0):** US hotspots get the full bundle (with
+  sparsity gaps in deep wilderness); non-US hotspots currently get only
+  `timezone` and `elevation_m` populated (both planet-scale), the rest `null`,
+  pending an upstream planet expansion. Treat `null` as "not resolved," not
+  "does not exist."
+
+  **Known wrinkle — `landclass` antimeridian false-positive:** a non-US hotspot
+  near 51–53°N can spuriously get a non-`null` `landclass` (it false-matches the
+  Aleutian "Rat Islands" US land-management polygon across the dateline). If you
+  consume `landclass`, treat a non-`null` value on a clearly non-US point as
+  suspect. Fix is tracked upstream.
 - **Live example (verbatim from CT104):**
 
 ```json
diff --git a/docs/PRODUCER-INTEGRATION.md b/docs/PRODUCER-INTEGRATION.md
index 02ce1bf..542c466 100644
--- a/docs/PRODUCER-INTEGRATION.md
+++ b/docs/PRODUCER-INTEGRATION.md
@@ -24,6 +24,7 @@ are intentionally not restated. Cross-references point into that doc.
 10. [Anti-patterns — what NOT to do](#10-anti-patterns--what-not-to-do)
 11. [Settings preview hook](#11-settings-preview-hook)
 12. [Acceptance gate for a new adapter](#12-acceptance-gate-for-a-new-adapter)
+13. [Enrichment contract](#13-enrichment-contract)
 
 ---
 
@@ -49,33 +50,47 @@ concerns (live in [`CONSUMER-INTEGRATION.md`](./CONSUMER-INTEGRATION.md)).
 > what it will."
 > — Matt, 2026-05-19
 
-Adapter authors translate that single sentence into a small number of concrete
-rules:
+The correct reading of that sentence: **Central is the consumer's only data
+plane.** A downstream consumer sees exactly what's on the wire and nothing
+more — it cannot do a follow-up lookup, cannot re-query the upstream, cannot
+reverse-geocode a coordinate on its own. So whatever Central does NOT put on
+the wire is, for every consumer, simply missing. "Gives it all" therefore means
+*give the consumer everything a reasonable consumer needs to act on the event*
+— not "give the upstream payload only."
+
+Adapter authors translate that into a small number of concrete rules:
 
 - **Preserve every upstream field.** Anything the upstream returns lives in
   `Event.data` verbatim. Adapters do not silently drop fields, even ones that
-  look redundant or low-value today.
-- **No enrichment.** Adapters do not reverse-geocode, do not call out to
-  upstream metadata endpoints during normal `poll()` flow, do not consult a
-  second source to "fill in" a missing field. If a downstream consumer wants
-  enrichment, that is consumer-side work.
-- **No opinionated translation.** Adapters do not coerce units, do not rename
-  fields to match a Central-wide vocabulary, do not collapse upstream
-  enumerations into Central's preferred labels.
-- **The only adapter-side transforms are mechanical.** Specifically:
-  subject-token normalization (camelCase → snake_case, agency-prefix splitting,
-  whitespace → underscore, lowercase) and dedup-key construction. Both are
-  deterministic functions of upstream identifiers. Nothing else.
+  look redundant or low-value today (see [§10.2](#102-silent-field-dropping)).
+- **Enrich, deliberately and centrally.** Location, timezone, elevation,
+  landclass and similar context that consumers reliably need should be resolved
+  once, by Central, and attached — not left for twelve consumers to each
+  re-derive (most of them can't). Enrichment runs through the framework
+  ([§13](#13-enrichment-contract)): an adapter declares `enrichment_locations`
+  and the supervisor attaches results under `Event.data["_enriched"]`.
+- **Namespace enrichment for provenance.** Central-derived fields live under
+  `_enriched.<enricher_name>`; everything else in `data` is upstream verbatim.
+  A consumer can always tell which is which.
+- **Fail gracefully to null, never to an exception.** Enrichment that can't
+  resolve a field returns `null` for it (a stable, documented field set), and a
+  total enrichment failure returns an all-null bundle. A geocoder outage must
+  never drop or corrupt the underlying event.
+- **No opinionated translation of the upstream payload.** Enrichment *adds*
+  namespaced fields; it does not rewrite upstream ones. Adapters still do not
+  coerce units, rename upstream fields, or collapse upstream enumerations inside
+  `data`. The only in-place adapter transforms remain mechanical: subject-token
+  normalization (camelCase → snake_case, agency-prefix splitting, whitespace →
+  underscore, lowercase) and dedup-key construction.
 
-This rules out a whole category of plausible-sounding work that prior reviews
-have already rejected. For instance, "enrich NWIS site rows with USGS
-monitoring-locations metadata during `poll()`" was proposed for Phase 3 and
-killed on this principle. The producer adds the field-preserving pipe; the pipe
-ends at JetStream publish; everything richer is a downstream concern.
-
-See [§10](#10-anti-patterns--what-not-to-do) for the enforced list of
-anti-patterns. Future authors should reject the same proposals on the same
-grounds.
+This reframes a Phase 2 rule. The earlier draft of this doc said "no
+enrichment — that's consumer-side work," and a proposal to enrich NWIS rows was
+rejected on those grounds. That reasoning is now inverted: consumers have no
+practical way to do that work, so Central does it. The constraint that survives
+is *where* and *how* — through the framework, namespaced, cached, failing to
+null — not *whether*. See [§10.1](#101-enrichment-outside-the-framework) for the
+remaining anti-pattern (enrichment done outside the framework) and
+[§13](#13-enrichment-contract) for the full contract.
 
 ---
 
@@ -625,18 +640,30 @@ adapter authors should mirror it. Do not restate it here.
 These are the patterns prior reviews have explicitly rejected. Reject them
 again on sight in a new-adapter PR.
 
-### 10.1 Enrichment during `poll()`
+### 10.1 Enrichment outside the framework
 
-No calls to upstream metadata endpoints, no reverse-geocode, no consultation
-of a second source to fill in fields the primary feed omitted. The "NWIS
-enrichment" Phase 3 proposal — joining live measurements against the
-monitoring-locations metadata endpoint during `poll()` — was rejected on the
-[§2](#2-the-design-principle) principle. Future proposals along the same
-lines get the same answer.
+Enrichment itself is **expected**, not forbidden — see
+[§2](#2-the-design-principle) and [§13](#13-enrichment-contract). Any adapter
+with location data should opt in by declaring `enrichment_locations` on the
+adapter class; the supervisor then runs the registered enrichers and attaches
+results under `Event.data["_enriched"]`.
 
-If enrichment is genuinely necessary, the right shape is a separate adapter
-(or a downstream consumer) — not an `if metadata_missing: await
-fetch_metadata()` branch buried in an adapter's `poll()`.
+The anti-pattern is doing enrichment the *wrong* way — outside the framework:
+
+- An `if missing: await fetch_metadata()` branch buried in an adapter's
+  `poll()`. This bypasses the cache (so every poll re-hits the geocoder), skips
+  the `_enriched` namespacing (so consumers can't tell upstream from
+  Central-derived), and gives up the never-raise/all-null safety net (so a
+  geocoder hiccup can take down the poll).
+- Writing enriched fields directly into the top level of `Event.data` instead
+  of under `_enriched`. That destroys provenance — a consumer can no longer
+  tell which fields came from the upstream feed and which Central added.
+- Standing up a parallel enrichment path (a second HTTP client, a private cache)
+  inside one adapter instead of registering a backend with the framework.
+
+The rule of thumb: declare `enrichment_locations`, let the supervisor do the
+work. If the framework can't express what you need, extend the framework
+([§13](#13-enrichment-contract)) — don't route around it inside an adapter.
 
 ### 10.2 Silent field dropping
 
@@ -821,3 +848,111 @@ requesting / granting merge.
 - [ ] **Full pytest suite green.**
 
 ---
+
+## 13. Enrichment contract
+
+Enrichment is how Central adds consumer-needed context (location names,
+timezone, elevation, landclass, …) that the upstream feed doesn't carry and a
+downstream consumer can't look up itself. It runs in the supervisor, after
+dedup and before the CloudEvents wrap, for any adapter that opts in. Results are
+namespaced under `Event.data["_enriched"]` so provenance stays explicit:
+everything under `_enriched` is Central-derived; everything else in `data` is
+upstream verbatim.
+
+### 13.1 Opting an adapter in
+
+Declare `enrichment_locations` on the adapter class — a list of
+`(lat_field, lon_field)` tuples naming top-level keys in `Event.data`:
+
+```python
+class FIRMSAdapter(SourceAdapter):
+    enrichment_locations = [("latitude", "longitude")]
+```
+
+Empty (the default on `SourceAdapter`) means "no enrichment, publish as-is."
+The supervisor uses the first tuple that resolves to a non-null coordinate pair,
+runs each registered enricher over `{"lat": …, "lon": …}`, and attaches the
+results. No adapter code calls enrichers directly.
+
+### 13.2 The `Enricher` Protocol
+
+An enricher is any object satisfying this Protocol (`central.enrichment.base`):
+
+- `name: str` — short identifier, used as the key under
+  `Event.data["_enriched"]`.
+- `async def enrich(self, location: dict[str, float]) -> dict[str, Any]` —
+  given `{"lat": float, "lon": float}`, return a flat dict of enrichment
+  fields. Fields it can't resolve are present with value `None` (not omitted).
+  **Must never raise** — implementations handle their own failures and return
+  an all-null bundle on total failure.
+
+### 13.3 `GeocoderEnricher` and the `GeocoderBackend` Protocol
+
+`GeocoderEnricher` (`central.enrichment.geocoder`, `name = "geocoder"`) is the
+only enricher today. It owns the cache and the canonical field normalization;
+the actual reverse-geocode is delegated to a pluggable backend satisfying the
+`GeocoderBackend` Protocol:
+
+- `async def reverse(self, lat: float, lon: float) -> dict[str, Any]` — return
+  the canonical geocoder fields (see [§13.5](#135-per-field-coverage)); fields
+  the backend can't resolve return `None`. Must never raise.
+
+Backends shipped: `NaviBackend` (composed Navi `/api/reverse/<lat>/<lon>`
+endpoint — name/address + timezone + landclass + elevation in one call),
+`PhotonBackend` (raw Photon, name/address only), `NominatimBackend` (OSM
+Nominatim, name/address only, with a configurable rate limit + `User-Agent`),
+and `NoOpBackend` (all-null — the default until an operator configures a real
+backend).
+
+### 13.4 Cache + failure semantics
+
+`GeocoderEnricher` is backed by a sqlite cache (`central.enrichment.cache`,
+`/var/lib/central/enrichment_cache.db`):
+
+- Key: `(enricher_name, lat_rounded, lon_rounded)`, coordinates rounded to 4
+  decimal places (~11 m). TTL is per-enricher, default 24h.
+- **Cache hit** → return cached bundle, no backend call.
+- **Cache miss** → call backend, cache the normalized result (**even an
+  all-null bundle** — so known-empty coordinates aren't re-hammered), return it.
+- **Backend raises** (a violation of the never-raise contract, or an
+  infrastructure error the backend chose to surface) → return an all-null
+  bundle and **do not cache** it, so the next event for that coordinate retries.
+
+Enrichment config (`EnrichmentConfig`: `enricher_class`, `backend_class`,
+`backend_settings`, `cache_ttl_s`) is read once at supervisor startup. Changing
+the enricher set is a restart, not a hot-reload.
+
+### 13.5 Per-field coverage
+
+The canonical geocoder bundle is exactly nine fields. They mirror
+`central.enrichment.geocoder.GEOCODER_FIELDS` (the single source of truth — this
+table must match it):
+
+| Field | US events | Non-US events today | Non-US after Photon planet expansion |
+|---|---|---|---|
+| `name` | populated (wilderness sparsity gaps) | null | populated |
+| `city` | populated (wilderness sparsity gaps) | null | populated |
+| `county` | populated (wilderness sparsity gaps) | null | populated |
+| `state` | populated (wilderness sparsity gaps) | null | populated |
+| `country` | populated (wilderness sparsity gaps) | null | populated |
+| `postal_code` | populated (wilderness sparsity gaps) | null | populated |
+| `timezone` | populated | populated (`tz_world` is planet-scale) | populated |
+| `landclass` | populated where PAD-US covers | null (PAD-US is US-only) | null |
+| `elevation_m` | populated | populated (planet-DEM) | populated |
+
+**Net for v0.5.0:** US events get a rich bundle; non-US events get `timezone` +
+`elevation_m` and the rest null. Photon planet expansion is queued on the Navi
+side with no firm ETA; when it lands, `NaviBackend` picks it up automatically
+with zero Central code changes.
+
+### 13.6 Known wrinkle — landclass antimeridian false-positive
+
+`landclass` is derived from a PostGIS `ST_Intersects` against PAD-US polygons.
+Points near 51–53°N **outside** the US can spuriously match the Aleutian "Rat
+Islands" PAD-US polygon (false matching across the antimeridian), yielding a
+non-null `landclass` that doesn't actually apply. This is a Navi-side bug being
+worked separately; until it's fixed, treat a non-null `landclass` on a clearly
+non-US point as suspect. Documented for consumers in
+`CONSUMER-INTEGRATION.md`.
+
+---
diff --git a/src/central/enrichment/backends/__init__.py b/src/central/enrichment/backends/__init__.py
index 309c273..7efd2f5 100644
--- a/src/central/enrichment/backends/__init__.py
+++ b/src/central/enrichment/backends/__init__.py
@@ -1,5 +1,8 @@
 """Geocoder backend implementations."""
 
+from central.enrichment.backends.navi import NaviBackend
+from central.enrichment.backends.nominatim import NominatimBackend
 from central.enrichment.backends.no_op import NoOpBackend
+from central.enrichment.backends.photon import PhotonBackend
 
-__all__ = ["NoOpBackend"]
+__all__ = ["NoOpBackend", "NaviBackend", "PhotonBackend", "NominatimBackend"]
diff --git a/src/central/enrichment/backends/navi.py b/src/central/enrichment/backends/navi.py
new file mode 100644
index 0000000..5335388
--- /dev/null
+++ b/src/central/enrichment/backends/navi.py
@@ -0,0 +1,79 @@
+"""Navi reverse-geocoding backend.
+
+Hits the composed Navi endpoint `<base_url>/api/reverse/<lat>/<lon>`, which
+already returns the canonical 9-field bundle (name, city, county, state,
+country, postal_code, timezone, landclass, elevation_m). Navi composes Photon
+(name/address) + tz_world (timezone) + PAD-US (landclass) + planet-DEM
+(elevation_m), so this backend is a near-passthrough mapping.
+
+Coverage today: US events get a rich bundle; non-US events get timezone +
+elevation_m populated (both planet-scale) and the rest null until Navi's
+Photon planet expansion lands (no Central change needed when it does).
+"""
+
+import asyncio
+import logging
+from typing import Any
+
+import aiohttp
+
+from central.enrichment.geocoder import GEOCODER_FIELDS, all_null_bundle
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_BASE_URL = "http://192.168.1.130:8440"
+# Boise — warmup coordinate, amortizes Photon/DEM cold-connection cost at startup.
+_WARMUP_LAT = 43.6150
+_WARMUP_LON = -116.2023
+
+
+class NaviBackend:
+    """GeocoderBackend backed by the composed Navi /api/reverse endpoint."""
+
+    def __init__(
+        self,
+        base_url: str = DEFAULT_BASE_URL,
+        timeout_s: float = 10.0,
+        headers: dict[str, str] | None = None,
+        warmup: bool = True,
+    ) -> None:
+        self._base_url = base_url.rstrip("/")
+        self._timeout_s = timeout_s
+        # Future-proof: drop an Authorization: Bearer … here config-only, no code change.
+        self._headers = dict(headers or {})
+        if warmup:
+            # Fire-and-forget warmup ping; only if a loop is running (it is under
+            # the supervisor's asyncio.run, not under sync test construction).
+            try:
+                loop = asyncio.get_running_loop()
+                loop.create_task(self._warmup())
+            except RuntimeError:
+                pass
+
+    def _url(self, lat: float, lon: float) -> str:
+        return f"{self._base_url}/api/reverse/{lat}/{lon}"
+
+    async def _warmup(self) -> None:
+        try:
+            await self._fetch(_WARMUP_LAT, _WARMUP_LON)
+        except Exception:
+            # Warmup is best-effort; a failure here must not break startup.
+            logger.debug("NaviBackend warmup ping failed (non-fatal)")
+
+    async def _fetch(self, lat: float, lon: float) -> dict[str, Any]:
+        async with aiohttp.ClientSession(
+            timeout=aiohttp.ClientTimeout(total=self._timeout_s),
+        ) as session:
+            async with session.get(self._url(lat, lon), headers=self._headers) as resp:
+                resp.raise_for_status()
+                return await resp.json()
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        try:
+            data = await self._fetch(lat, lon)
+        except Exception:
+            # Non-200, network error, timeout, malformed JSON — never raise.
+            logger.debug("NaviBackend reverse failed; returning all-null bundle")
+            return all_null_bundle()
+        # Navi's response already matches the canonical shape; map defensively.
+        return {field: data.get(field) for field in GEOCODER_FIELDS}
diff --git a/src/central/enrichment/backends/nominatim.py b/src/central/enrichment/backends/nominatim.py
new file mode 100644
index 0000000..0b3a9cb
--- /dev/null
+++ b/src/central/enrichment/backends/nominatim.py
@@ -0,0 +1,95 @@
+"""OSM Nominatim reverse-geocoding backend.
+
+Works against public OSM Nominatim (1 req/sec + User-Agent required) or a
+self-hosted instance (no limit). Resolves name + address only; timezone,
+landclass, and elevation_m are nulled (not in the Nominatim reverse response).
+
+Nominatim jsonv2 reverse response shape:
+    {"display_name": "...", "name": "...",
+     "address": {city|town|village, county, state, country, postcode, ...}}
+"""
+
+import asyncio
+import logging
+import time
+from typing import Any
+from urllib.parse import urlencode
+
+import aiohttp
+
+from central.enrichment.geocoder import all_null_bundle
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_BASE_URL = "https://nominatim.openstreetmap.org"
+DEFAULT_USER_AGENT = "central-enrichment/0.5 (https://github.com/zvx-echo6/central)"
+
+
+class NominatimBackend:
+    """GeocoderBackend backed by an OSM Nominatim /reverse endpoint.
+
+    rate_limit_per_sec throttles outbound requests (public OSM requires <= 1/s);
+    set it to 0 to disable for self-hosted instances.
+    """
+
+    def __init__(
+        self,
+        base_url: str = DEFAULT_BASE_URL,
+        user_agent: str = DEFAULT_USER_AGENT,
+        rate_limit_per_sec: float = 1.0,
+        timeout_s: float = 10.0,
+    ) -> None:
+        self._base_url = base_url.rstrip("/")
+        self._user_agent = user_agent
+        self._min_interval = (1.0 / rate_limit_per_sec) if rate_limit_per_sec > 0 else 0.0
+        self._timeout_s = timeout_s
+        self._rl_lock = asyncio.Lock()
+        self._last_request_at = 0.0
+
+    def _url(self, lat: float, lon: float) -> str:
+        qs = urlencode({"lat": lat, "lon": lon, "format": "jsonv2"})
+        return f"{self._base_url}/reverse?{qs}"
+
+    def _request_headers(self) -> dict[str, str]:
+        # Public Nominatim rejects requests without an identifying User-Agent.
+        return {"User-Agent": self._user_agent}
+
+    async def _throttle(self) -> None:
+        if self._min_interval <= 0:
+            return
+        async with self._rl_lock:
+            now = time.monotonic()
+            wait = self._last_request_at + self._min_interval - now
+            if wait > 0:
+                await asyncio.sleep(wait)
+            self._last_request_at = time.monotonic()
+
+    async def _fetch(self, lat: float, lon: float) -> dict[str, Any]:
+        async with aiohttp.ClientSession(
+            timeout=aiohttp.ClientTimeout(total=self._timeout_s),
+        ) as session:
+            async with session.get(
+                self._url(lat, lon), headers=self._request_headers()
+            ) as resp:
+                resp.raise_for_status()
+                return await resp.json()
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        try:
+            await self._throttle()
+            data = await self._fetch(lat, lon)
+            addr = data.get("address", {}) or {}
+        except Exception:
+            logger.debug("NominatimBackend reverse failed; returning all-null bundle")
+            return all_null_bundle()
+        return {
+            "name": data.get("name") or data.get("display_name"),
+            "city": addr.get("city") or addr.get("town") or addr.get("village"),
+            "county": addr.get("county"),
+            "state": addr.get("state"),
+            "country": addr.get("country"),
+            "postal_code": addr.get("postcode"),
+            "timezone": None,   # not in Nominatim reverse response
+            "landclass": None,  # Navi-composed-endpoint only
+            "elevation_m": None,  # Navi-composed-endpoint only
+        }
diff --git a/src/central/enrichment/backends/photon.py b/src/central/enrichment/backends/photon.py
new file mode 100644
index 0000000..2e75814
--- /dev/null
+++ b/src/central/enrichment/backends/photon.py
@@ -0,0 +1,69 @@
+"""Raw Photon reverse-geocoding backend.
+
+For deployers who run a Photon instance directly, without the composed
+Navi-style endpoint. Photon resolves name + address only — timezone,
+landclass, and elevation_m are Navi-composed-endpoint extras and are nulled
+here.
+
+Photon reverse response shape:
+    {"features": [{"properties": {name, city, county, state, country,
+                                  postcode, ...}, "geometry": {...}}]}
+"""
+
+import logging
+from typing import Any
+from urllib.parse import urlencode
+
+import aiohttp
+
+from central.enrichment.geocoder import all_null_bundle
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_BASE_URL = "http://localhost:2322"
+
+
+class PhotonBackend:
+    """GeocoderBackend backed by a raw Photon /reverse endpoint."""
+
+    def __init__(
+        self,
+        base_url: str = DEFAULT_BASE_URL,
+        timeout_s: float = 10.0,
+        headers: dict[str, str] | None = None,
+    ) -> None:
+        self._base_url = base_url.rstrip("/")
+        self._timeout_s = timeout_s
+        self._headers = dict(headers or {})
+
+    def _url(self, lat: float, lon: float) -> str:
+        qs = urlencode({"lat": lat, "lon": lon, "limit": 1})
+        return f"{self._base_url}/reverse?{qs}"
+
+    async def _fetch(self, lat: float, lon: float) -> dict[str, Any]:
+        async with aiohttp.ClientSession(
+            timeout=aiohttp.ClientTimeout(total=self._timeout_s),
+        ) as session:
+            async with session.get(self._url(lat, lon), headers=self._headers) as resp:
+                resp.raise_for_status()
+                return await resp.json()
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        try:
+            data = await self._fetch(lat, lon)
+            features = data.get("features") or []
+            props = features[0].get("properties", {}) if features else {}
+        except Exception:
+            logger.debug("PhotonBackend reverse failed; returning all-null bundle")
+            return all_null_bundle()
+        return {
+            "name": props.get("name"),
+            "city": props.get("city"),
+            "county": props.get("county"),
+            "state": props.get("state"),
+            "country": props.get("country"),
+            "postal_code": props.get("postcode"),  # Photon names it 'postcode'
+            "timezone": None,   # not provided by raw Photon
+            "landclass": None,  # Navi-composed-endpoint only
+            "elevation_m": None,  # Navi-composed-endpoint only
+        }
diff --git a/src/central/supervisor.py b/src/central/supervisor.py
index 8ca6be9..b3ec997 100644
--- a/src/central/supervisor.py
+++ b/src/central/supervisor.py
@@ -24,7 +24,10 @@ from central.api_key_resolver import resolve_api_key_alias
 from central.config_models import EnrichmentConfig
 from central.enrichment.base import Enricher
 from central.enrichment.cache import EnrichmentCache
+from central.enrichment.backends.navi import NaviBackend
+from central.enrichment.backends.nominatim import NominatimBackend
 from central.enrichment.backends.no_op import NoOpBackend
+from central.enrichment.backends.photon import PhotonBackend
 from central.enrichment.geocoder import GeocoderEnricher
 from central.models import Event
 from central.stream_manager import StreamManager
@@ -33,9 +36,13 @@ CURSOR_DB_PATH = Path("/var/lib/central/cursors.db")
 ENRICHMENT_CACHE_DB_PATH = Path("/var/lib/central/enrichment_cache.db")
 
 # Enricher / backend class-name registries for EnrichmentConfig resolution.
-# PR J ships GeocoderEnricher + NoOpBackend only; PR K extends these.
 _ENRICHER_REGISTRY: dict[str, type] = {"GeocoderEnricher": GeocoderEnricher}
-_BACKEND_REGISTRY: dict[str, type] = {"NoOpBackend": NoOpBackend}
+_BACKEND_REGISTRY: dict[str, type] = {
+    "NoOpBackend": NoOpBackend,
+    "NaviBackend": NaviBackend,
+    "PhotonBackend": PhotonBackend,
+    "NominatimBackend": NominatimBackend,
+}
 
 
 def build_enrichers(
diff --git a/tests/test_navi_backend.py b/tests/test_navi_backend.py
new file mode 100644
index 0000000..98870ba
--- /dev/null
+++ b/tests/test_navi_backend.py
@@ -0,0 +1,120 @@
+"""Tests for NaviBackend (composed Navi /api/reverse endpoint).
+
+HTTP is exercised via patching the backend's `_fetch` (the codebase has no
+aioresponses/respx dep); URL construction is asserted on the pure `_url`
+helper. An env-gated integration smoke against the live Navi endpoint is
+skipped by default.
+"""
+
+import os
+from unittest.mock import AsyncMock
+
+import pytest
+
+from central.enrichment.backends.navi import NaviBackend
+from central.enrichment.geocoder import GEOCODER_FIELDS, all_null_bundle
+
+# Full Navi response — already canonical shape.
+_NAVI_OK = {
+    "name": "Where you are",
+    "city": "Boise",
+    "county": "Ada",
+    "state": "Idaho",
+    "country": "United States",
+    "postal_code": "83702",
+    "timezone": "America/Boise",
+    "landclass": "Public — National Forest",
+    "elevation_m": 824,
+}
+
+
+def _backend() -> NaviBackend:
+    # warmup=False so construction issues no background task in tests.
+    return NaviBackend(base_url="http://navi.test:8440", warmup=False)
+
+
+def test_url_construction():
+    b = _backend()
+    assert b._url(43.615, -116.2023) == "http://navi.test:8440/api/reverse/43.615/-116.2023"
+
+
+def test_base_url_trailing_slash_stripped():
+    b = NaviBackend(base_url="http://navi.test:8440/", warmup=False)
+    assert b._url(1.0, 2.0) == "http://navi.test:8440/api/reverse/1.0/2.0"
+
+
+@pytest.mark.asyncio
+async def test_happy_path_passthrough():
+    b = _backend()
+    b._fetch = AsyncMock(return_value=dict(_NAVI_OK))
+    result = await b.reverse(43.615, -116.2023)
+    assert result == _NAVI_OK
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+
+
+@pytest.mark.asyncio
+async def test_partial_nulls_preserved():
+    """Navi 200-with-nulls (non-US: timezone + elevation, rest null)."""
+    partial = {**all_null_bundle(), "timezone": "Europe/Paris", "elevation_m": 35}
+    b = _backend()
+    b._fetch = AsyncMock(return_value=partial)
+    result = await b.reverse(48.85, 2.35)
+    assert result["timezone"] == "Europe/Paris"
+    assert result["elevation_m"] == 35
+    assert result["city"] is None
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+
+
+@pytest.mark.asyncio
+async def test_extra_keys_dropped():
+    b = _backend()
+    b._fetch = AsyncMock(return_value={**_NAVI_OK, "debug_internal": "leak"})
+    result = await b.reverse(1.0, 2.0)
+    assert "debug_internal" not in result
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+
+
+@pytest.mark.asyncio
+async def test_network_error_returns_all_null_never_raises():
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=ConnectionError("boom"))
+    result = await b.reverse(1.0, 2.0)
+    assert result == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_timeout_returns_all_null():
+    import asyncio
+
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=asyncio.TimeoutError())
+    assert await b.reverse(1.0, 2.0) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_malformed_response_returns_all_null():
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=ValueError("not json"))
+    assert await b.reverse(1.0, 2.0) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_headers_passed_through_config():
+    b = NaviBackend(base_url="http://navi.test", headers={"Authorization": "Bearer x"}, warmup=False)
+    assert b._headers == {"Authorization": "Bearer x"}
+
+
+@pytest.mark.asyncio
+@pytest.mark.skipif(
+    os.environ.get("NAVI_INTEGRATION_TEST") != "1",
+    reason="set NAVI_INTEGRATION_TEST=1 to hit the live Navi endpoint",
+)
+async def test_live_navi_boise():
+    """Integration smoke against the real endpoint (default skipped)."""
+    b = NaviBackend(warmup=False)  # default base_url
+    result = await b.reverse(43.6150, -116.2023)
+    assert result["name"] == "Where you are"
+    assert result["city"] == "Boise"
+    assert result["state"] == "Idaho"
+    assert result["elevation_m"] is not None
+    assert abs(float(result["elevation_m"]) - 824) < 50
diff --git a/tests/test_nominatim_backend.py b/tests/test_nominatim_backend.py
new file mode 100644
index 0000000..6663d23
--- /dev/null
+++ b/tests/test_nominatim_backend.py
@@ -0,0 +1,118 @@
+"""Tests for NominatimBackend (OSM Nominatim /reverse jsonv2)."""
+
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from central.enrichment.backends.nominatim import (
+    DEFAULT_USER_AGENT,
+    NominatimBackend,
+)
+from central.enrichment.geocoder import GEOCODER_FIELDS, all_null_bundle
+
+_NOMINATIM_OK = {
+    "name": "Boise",
+    "display_name": "Boise, Ada County, Idaho, United States",
+    "address": {
+        "city": "Boise",
+        "county": "Ada County",
+        "state": "Idaho",
+        "country": "United States",
+        "postcode": "83702",
+    },
+}
+
+
+def _backend(**kw) -> NominatimBackend:
+    kw.setdefault("base_url", "http://nominatim.test")
+    kw.setdefault("rate_limit_per_sec", 0)  # disabled by default in tests
+    return NominatimBackend(**kw)
+
+
+def test_url_and_format():
+    b = _backend()
+    url = b._url(43.6, -116.2)
+    assert url.startswith("http://nominatim.test/reverse?")
+    assert "format=jsonv2" in url and "lat=43.6" in url and "lon=-116.2" in url
+
+
+def test_user_agent_header_present():
+    b = _backend()
+    assert b._request_headers()["User-Agent"] == DEFAULT_USER_AGENT
+
+
+def test_custom_user_agent():
+    b = _backend(user_agent="myapp/1.0 (me@example.com)")
+    assert b._request_headers()["User-Agent"] == "myapp/1.0 (me@example.com)"
+
+
+@pytest.mark.asyncio
+async def test_happy_path_maps_address_block():
+    b = _backend()
+    b._fetch = AsyncMock(return_value=dict(_NOMINATIM_OK))
+    result = await b.reverse(43.6, -116.2)
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+    assert result["name"] == "Boise"
+    assert result["city"] == "Boise"
+    assert result["county"] == "Ada County"
+    assert result["state"] == "Idaho"
+    assert result["country"] == "United States"
+    assert result["postal_code"] == "83702"
+
+
+@pytest.mark.asyncio
+async def test_navi_only_fields_null():
+    b = _backend()
+    b._fetch = AsyncMock(return_value=dict(_NOMINATIM_OK))
+    result = await b.reverse(43.6, -116.2)
+    assert result["timezone"] is None
+    assert result["landclass"] is None
+    assert result["elevation_m"] is None
+
+
+@pytest.mark.asyncio
+async def test_city_falls_back_to_town_then_village():
+    b = _backend()
+    b._fetch = AsyncMock(return_value={"address": {"village": "Tinytown"}})
+    result = await b.reverse(1.0, 2.0)
+    assert result["city"] == "Tinytown"
+
+
+@pytest.mark.asyncio
+async def test_network_error_returns_all_null():
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=ConnectionError("down"))
+    assert await b.reverse(1.0, 2.0) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_malformed_json_returns_all_null():
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=ValueError("bad"))
+    assert await b.reverse(1.0, 2.0) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_rate_limit_disabled_does_not_sleep():
+    b = _backend(rate_limit_per_sec=0)
+    with patch("central.enrichment.backends.nominatim.asyncio.sleep") as slp:
+        await b._throttle()
+        await b._throttle()
+        slp.assert_not_called()
+
+
+@pytest.mark.asyncio
+async def test_rate_limit_spaces_consecutive_requests():
+    """With a 1/sec limit, the second back-to-back call must sleep a positive
+    interval. Mock monotonic to a fixed instant so the throttle computes a wait."""
+    b = _backend(rate_limit_per_sec=1.0)
+    sleeps: list[float] = []
+
+    async def _fake_sleep(d):
+        sleeps.append(d)
+
+    with patch("central.enrichment.backends.nominatim.time.monotonic", return_value=100.0), \
+         patch("central.enrichment.backends.nominatim.asyncio.sleep", side_effect=_fake_sleep):
+        await b._throttle()  # first: last_request_at was 0 -> no wait
+        await b._throttle()  # second: now==100, last==100 -> wait ~1.0s
+    assert any(d > 0 for d in sleeps), f"expected a positive throttle sleep, got {sleeps}"
diff --git a/tests/test_photon_backend.py b/tests/test_photon_backend.py
new file mode 100644
index 0000000..f224d21
--- /dev/null
+++ b/tests/test_photon_backend.py
@@ -0,0 +1,92 @@
+"""Tests for PhotonBackend (raw Photon /reverse)."""
+
+from unittest.mock import AsyncMock
+
+import pytest
+
+from central.enrichment.backends.photon import PhotonBackend
+from central.enrichment.geocoder import GEOCODER_FIELDS, all_null_bundle
+
+# Photon reverse response shape.
+_PHOTON_OK = {
+    "features": [
+        {
+            "properties": {
+                "name": "Boise",
+                "city": "Boise",
+                "county": "Ada County",
+                "state": "Idaho",
+                "country": "United States",
+                "postcode": "83702",
+                "osm_key": "place",
+            },
+            "geometry": {"type": "Point", "coordinates": [-116.2, 43.6]},
+        }
+    ]
+}
+
+
+def _backend() -> PhotonBackend:
+    return PhotonBackend(base_url="http://photon.test:2322")
+
+
+def test_url_construction():
+    b = _backend()
+    url = b._url(43.6, -116.2)
+    assert url.startswith("http://photon.test:2322/reverse?")
+    assert "lat=43.6" in url and "lon=-116.2" in url and "limit=1" in url
+
+
+@pytest.mark.asyncio
+async def test_happy_path_maps_to_canonical():
+    b = _backend()
+    b._fetch = AsyncMock(return_value=dict(_PHOTON_OK))
+    result = await b.reverse(43.6, -116.2)
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+    assert result["city"] == "Boise"
+    assert result["county"] == "Ada County"
+    assert result["state"] == "Idaho"
+    assert result["country"] == "United States"
+    assert result["postal_code"] == "83702"  # mapped from Photon 'postcode'
+
+
+@pytest.mark.asyncio
+async def test_navi_only_fields_are_null():
+    b = _backend()
+    b._fetch = AsyncMock(return_value=dict(_PHOTON_OK))
+    result = await b.reverse(43.6, -116.2)
+    assert result["timezone"] is None
+    assert result["landclass"] is None
+    assert result["elevation_m"] is None
+
+
+@pytest.mark.asyncio
+async def test_empty_features_returns_all_null():
+    b = _backend()
+    b._fetch = AsyncMock(return_value={"features": []})
+    assert await b.reverse(0.0, 0.0) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_missing_properties_keys_become_null():
+    b = _backend()
+    b._fetch = AsyncMock(return_value={"features": [{"properties": {"name": "X"}}]})
+    result = await b.reverse(1.0, 2.0)
+    assert result["name"] == "X"
+    assert result["city"] is None
+    assert result["postal_code"] is None
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+
+
+@pytest.mark.asyncio
+async def test_network_error_returns_all_null():
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=ConnectionError("down"))
+    assert await b.reverse(1.0, 2.0) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_malformed_json_returns_all_null():
+    b = _backend()
+    b._fetch = AsyncMock(side_effect=ValueError("bad json"))
+    assert await b.reverse(1.0, 2.0) == all_null_bundle()
diff --git a/tests/test_producer_doc.py b/tests/test_producer_doc.py
index aef32e7..07abbef 100644
--- a/tests/test_producer_doc.py
+++ b/tests/test_producer_doc.py
@@ -23,8 +23,14 @@ from pathlib import Path
 
 from central.adapter import SourceAdapter
 from central.adapter_discovery import discover_adapters
+from central.enrichment.geocoder import GEOCODER_FIELDS
 from central.streams import STREAMS
 
+# The verbatim design-principle quote that must stay in §2 (Matt, 2026-05-19).
+_DESIGN_PRINCIPLE_QUOTE = (
+    "Central takes it all and gives it all. It's up to the pipe to do with it"
+)
+
 DOC_PATH = Path(__file__).resolve().parents[1] / "docs" / "PRODUCER-INTEGRATION.md"
 
 
@@ -186,6 +192,48 @@ def test_streams_snippet_quotes_live_registry():
     )
 
 
+def _section(doc: str, header_re: str) -> str:
+    """Return the body of the section whose header matches header_re, up to the
+    next same-or-higher-level header."""
+    m = re.search(header_re + r"\s*\n(.*?)(?=^## |\Z)", doc, re.DOTALL | re.MULTILINE)
+    assert m, f"doc missing section matching {header_re!r}"
+    return m.group(1)
+
+
+def test_design_principle_quote_present_in_section_2():
+    """§2 must still carry the verbatim Matt quote — the reframe changes the
+    translation beneath it, not the quote itself."""
+    section = _section(_doc_text(), r"^## 2\. The design principle")
+    assert _DESIGN_PRINCIPLE_QUOTE in section, "verbatim design-principle quote missing from §2"
+
+
+def test_anti_pattern_10_1_section_exists():
+    """§10.1 must still exist as a subsection (content reframed to
+    'enrichment outside the framework', structure preserved)."""
+    doc = _doc_text()
+    assert re.search(r"^### 10\.1 ", doc, re.MULTILINE), "doc missing '### 10.1' subsection"
+
+
+def test_enrichment_contract_section_13_has_all_protocol_references():
+    """New §13 must name all four enrichment contract types verbatim."""
+    section = _section(_doc_text(), r"^## 13\. Enrichment contract")
+    for ref in ("Enricher", "GeocoderEnricher", "GeocoderBackend", "NoOpBackend"):
+        assert ref in section, f"§13 missing reference to {ref!r}"
+
+
+def test_enrichment_coverage_matrix_lists_exactly_geocoder_fields():
+    """The §13 per-field coverage matrix must list exactly the canonical
+    GEOCODER_FIELDS — derived from code, not hardcoded here."""
+    section = _section(_doc_text(), r"^## 13\. Enrichment contract")
+    # Matrix rows look like: | `field_name` | ... |
+    row_fields = set(re.findall(r"^\|\s*`([a-z_]+)`\s*\|", section, re.MULTILINE))
+    assert row_fields == set(GEOCODER_FIELDS), (
+        f"coverage-matrix field drift: "
+        f"doc-only={row_fields - set(GEOCODER_FIELDS)}, "
+        f"code-only={set(GEOCODER_FIELDS) - row_fields}"
+    )
+
+
 def test_no_orphan_adapter_references_in_anti_patterns():
     """Anti-patterns section names two real adapter modules as examples
     (firms, inciweb in §10.4). Those names must still resolve via