diff --git a/src/central/adapter.py b/src/central/adapter.py
index 76ab04e..b923c7c 100644
--- a/src/central/adapter.py
+++ b/src/central/adapter.py
@@ -40,7 +40,14 @@ class SourceAdapter(ABC):
     the wizard validates it against staged api_keys state."""
     wizard_order: int | None = None
     default_cadence_s: int
-    
+
+    enrichment_locations: list[tuple[str, str]] = []
+    """Coordinate field paths the supervisor enriches, as (lat_field, lon_field)
+    tuples into Event.data. Empty (the default) means publish as-is — no
+    enrichment. Each tuple names top-level keys in Event.data holding a
+    latitude and longitude; the supervisor extracts them, runs registered
+    enrichers, and attaches results under Event.data["_enriched"]."""
+
     @abstractmethod
     async def poll(self) -> AsyncIterator[Event]:
         """
diff --git a/src/central/adapters/firms.py b/src/central/adapters/firms.py
index c9b4efb..46a0d81 100644
--- a/src/central/adapters/firms.py
+++ b/src/central/adapters/firms.py
@@ -70,6 +70,9 @@ class FIRMSAdapter(SourceAdapter):
     wizard_order = 2
     default_cadence_s = 300
 
+    # Enrichment pilot (PR J): FIRMS rows carry top-level latitude/longitude.
+    enrichment_locations = [("latitude", "longitude")]
+
     def __init__(
         self,
         config: AdapterConfig,
diff --git a/src/central/api_key_resolver.py b/src/central/api_key_resolver.py
new file mode 100644
index 0000000..e5c3ffa
--- /dev/null
+++ b/src/central/api_key_resolver.py
@@ -0,0 +1,82 @@
+"""Resolve an adapter row's effective api-key alias and check existence.
+
+Four call sites share this answer: the /adapters list view, the
+/adapters/{name} edit form (GET), the same edit form's POST error
+re-render path, and the supervisor's adapter-start precondition.
+Previously each inlined a predicate that compared the hardcoded
+SourceAdapter class attribute `requires_api_key` against `config.api_keys`,
+ignoring the per-row `settings[api_key_field]` value the operator
+actually selected. An operator could pick alias "firms_production" via
+the form, store a working key under that alias, and still see the
+"⚠️ API Key Missing" chip + a disabled enable checkbox + the supervisor
+refusing to start the adapter — all from the same root cause.
+
+Two entry points:
+
+- `resolve_api_key_alias`  — sync. Pure function of (cls, settings).
+  Returns the alias the row should consult, or None when no key is
+  required (no SQL needed). Supervisor uses this directly because it
+  already has a ConfigStore and does its own key fetch.
+
+- `adapter_has_resolved_api_key` — async. Wraps the sync resolver with
+  the existence SELECT against config.api_keys. The three GUI route
+  call sites use this.
+
+Resolution order (same as the adapter's runtime read in __init__):
+  1. requires_api_key is None  -> no key needed.
+  2. settings[api_key_field] is a non-empty string -> use that.
+  3. fall back to the requires_api_key class-attribute default.
+"""
+
+from typing import Any
+
+from central.adapter import SourceAdapter
+
+
+def resolve_api_key_alias(
+    adapter_cls: type[SourceAdapter] | None,
+    settings: dict | None,
+) -> str | None:
+    """Return the api-key alias for this adapter row, or None when no key is required.
+
+    Pure function — no IO, no SQL. Same resolution order the adapter's own
+    __init__ uses when reading the alias out of config.settings.
+    """
+    if adapter_cls is None or adapter_cls.requires_api_key is None:
+        return None
+    field = adapter_cls.api_key_field
+    if field and settings:
+        value = settings.get(field)
+        if isinstance(value, str) and value.strip():
+            return value.strip()
+    return adapter_cls.requires_api_key
+
+
+async def adapter_has_resolved_api_key(
+    conn: Any,
+    adapter_cls: type[SourceAdapter] | None,
+    settings: dict | None,
+) -> tuple[bool, str | None]:
+    """Return (has_key, resolved_alias) for one adapter row.
+
+    Args:
+        conn: asyncpg connection or any object exposing an awaitable fetchval
+            with the same signature.
+        adapter_cls: The discovered SourceAdapter subclass for this row, or
+            None when the row references an adapter no longer in the codebase.
+        settings: The row's jsonb settings dict, or None when the row has no
+            settings stored yet.
+
+    Returns:
+        (has_key, resolved_alias). When the adapter does not require an api
+        key (requires_api_key is None) or no adapter class is available,
+        returns (True, None) and no SQL is issued.
+    """
+    alias = resolve_api_key_alias(adapter_cls, settings)
+    if alias is None:
+        return True, None
+    has_key = await conn.fetchval(
+        "SELECT 1 FROM config.api_keys WHERE alias = $1",
+        alias,
+    )
+    return bool(has_key), alias
diff --git a/src/central/config_models.py b/src/central/config_models.py
index 5516bc1..557423a 100644
--- a/src/central/config_models.py
+++ b/src/central/config_models.py
@@ -47,6 +47,28 @@ class AdapterConfig(BaseModel):
         return self.paused_at is not None
 
 
+class EnrichmentConfig(BaseModel):
+    """Configuration for the supervisor's enrichment stage.
+
+    Read once at supervisor startup (hot-reload is out of scope for PR J).
+    Defaults wire the GeocoderEnricher to the NoOpBackend (all-null bundle);
+    real backends arrive in PR K via backend_class + backend_settings.
+    """
+
+    enricher_class: str = Field(
+        default="GeocoderEnricher", description="Enricher class name to instantiate"
+    )
+    backend_class: str = Field(
+        default="NoOpBackend", description="Backend class name to instantiate"
+    )
+    backend_settings: dict[str, Any] = Field(
+        default_factory=dict, description="Keyword args passed to the backend constructor"
+    )
+    cache_ttl_s: int = Field(
+        default=86400, description="Enrichment cache TTL in seconds (default 24h)"
+    )
+
+
 class StreamConfig(BaseModel):
     """Configuration for a JetStream stream."""
     
diff --git a/src/central/enrichment/__init__.py b/src/central/enrichment/__init__.py
new file mode 100644
index 0000000..0e32625
--- /dev/null
+++ b/src/central/enrichment/__init__.py
@@ -0,0 +1,28 @@
+"""Central enrichment framework.
+
+The supervisor runs registered enrichers over each event whose adapter
+declares `enrichment_locations`, attaching results under
+`event.data["_enriched"][<enricher.name>]`. Provenance is explicit: anything
+under `_enriched` is Central-derived; everything else in `data` is upstream
+verbatim.
+"""
+
+from central.enrichment.backends.no_op import NoOpBackend
+from central.enrichment.base import Enricher
+from central.enrichment.cache import EnrichmentCache
+from central.enrichment.geocoder import (
+    GEOCODER_FIELDS,
+    GeocoderBackend,
+    GeocoderEnricher,
+    all_null_bundle,
+)
+
+__all__ = [
+    "Enricher",
+    "EnrichmentCache",
+    "GeocoderEnricher",
+    "GeocoderBackend",
+    "GEOCODER_FIELDS",
+    "all_null_bundle",
+    "NoOpBackend",
+]
diff --git a/src/central/enrichment/backends/__init__.py b/src/central/enrichment/backends/__init__.py
new file mode 100644
index 0000000..309c273
--- /dev/null
+++ b/src/central/enrichment/backends/__init__.py
@@ -0,0 +1,5 @@
+"""Geocoder backend implementations."""
+
+from central.enrichment.backends.no_op import NoOpBackend
+
+__all__ = ["NoOpBackend"]
diff --git a/src/central/enrichment/backends/no_op.py b/src/central/enrichment/backends/no_op.py
new file mode 100644
index 0000000..77b0567
--- /dev/null
+++ b/src/central/enrichment/backends/no_op.py
@@ -0,0 +1,17 @@
+"""No-op geocoder backend — returns an all-null bundle for every input.
+
+The default backend in PR J. Real backends (Navi, Photon, Nominatim) land in
+PR K; until then the framework is exercisable end-to-end with NoOpBackend,
+which satisfies the GeocoderBackend contract while resolving nothing.
+"""
+
+from typing import Any
+
+from central.enrichment.geocoder import all_null_bundle
+
+
+class NoOpBackend:
+    """GeocoderBackend that resolves no fields."""
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        return all_null_bundle()
diff --git a/src/central/enrichment/base.py b/src/central/enrichment/base.py
new file mode 100644
index 0000000..7249355
--- /dev/null
+++ b/src/central/enrichment/base.py
@@ -0,0 +1,30 @@
+"""Enricher protocol — the framework-level contract.
+
+An Enricher takes a single location and returns a flat dict of enrichment
+fields. The supervisor attaches each enricher's result under
+`event.data["_enriched"][enricher.name]` before publishing. Everything under
+`_enriched` is Central-provenance; everything else in `data` is upstream
+verbatim.
+"""
+
+from typing import Any, Protocol, runtime_checkable
+
+
+@runtime_checkable
+class Enricher(Protocol):
+    """Pluggable enrichment unit.
+
+    name: short identifier, used as the key under event.data["_enriched"].
+    """
+
+    name: str
+
+    async def enrich(self, location: dict[str, float]) -> dict[str, Any]:
+        """Given a location ({"lat": float, "lon": float}), return enrichment fields.
+
+        Fields the enricher can't resolve are present with value None (NOT
+        omitted) so consumers see a stable field set. Implementations must
+        NEVER raise — they handle their own failures and return an all-null
+        bundle on total failure.
+        """
+        ...
diff --git a/src/central/enrichment/cache.py b/src/central/enrichment/cache.py
new file mode 100644
index 0000000..06be7af
--- /dev/null
+++ b/src/central/enrichment/cache.py
@@ -0,0 +1,126 @@
+"""SQLite-backed enrichment cache with rounded-coords keys + TTL.
+
+Keyed on (enricher_name, lat_rounded, lon_rounded) where coordinates are
+rounded to 4 decimal places (~11 m). Uses stdlib sqlite3 off the event loop
+via asyncio.to_thread (no async-sqlite dependency in the project). A fresh
+connection is opened per operation — sqlite3 connections are not safe to
+share across threads, and to_thread may run ops on different pool threads.
+"""
+
+import asyncio
+import json
+import logging
+import sqlite3
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+_COORD_PRECISION = 4
+
+_SCHEMA = """
+CREATE TABLE IF NOT EXISTS enrichment_cache (
+    enricher_name TEXT NOT NULL,
+    lat_rounded REAL NOT NULL,
+    lon_rounded REAL NOT NULL,
+    payload_json TEXT NOT NULL,
+    cached_at TEXT NOT NULL,
+    PRIMARY KEY (enricher_name, lat_rounded, lon_rounded)
+)
+"""
+
+
+def round_coord(value: float) -> float:
+    """Round a coordinate to the cache-key precision (4 dp)."""
+    return round(float(value), _COORD_PRECISION)
+
+
+class EnrichmentCache:
+    """Thread-offloaded sqlite cache for enrichment bundles."""
+
+    def __init__(self, db_path: str | Path, ttl_s: int = 86400) -> None:
+        self._db_path = Path(db_path)
+        self._ttl_s = ttl_s
+        self._db_path.parent.mkdir(parents=True, exist_ok=True)
+        self._init_db()
+
+    def _connect(self) -> sqlite3.Connection:
+        return sqlite3.connect(self._db_path, timeout=30)
+
+    def _init_db(self) -> None:
+        conn = self._connect()
+        try:
+            conn.execute(_SCHEMA)
+            conn.commit()
+        finally:
+            conn.close()
+
+    # --- sync bodies (run inside asyncio.to_thread) ------------------------
+
+    def _get_sync(self, enricher_name: str, lat: float, lon: float) -> dict[str, Any] | None:
+        lat_r = round_coord(lat)
+        lon_r = round_coord(lon)
+        conn = self._connect()
+        try:
+            cur = conn.execute(
+                """
+                SELECT payload_json, cached_at FROM enrichment_cache
+                WHERE enricher_name = ? AND lat_rounded = ? AND lon_rounded = ?
+                """,
+                (enricher_name, lat_r, lon_r),
+            )
+            row = cur.fetchone()
+        finally:
+            conn.close()
+        if row is None:
+            return None
+        payload_json, cached_at_iso = row
+        if self._is_expired(cached_at_iso):
+            return None
+        return json.loads(payload_json)
+
+    def _set_sync(
+        self, enricher_name: str, lat: float, lon: float, payload: dict[str, Any]
+    ) -> None:
+        lat_r = round_coord(lat)
+        lon_r = round_coord(lon)
+        now_iso = datetime.now(timezone.utc).isoformat()
+        conn = self._connect()
+        try:
+            conn.execute(
+                """
+                INSERT INTO enrichment_cache
+                    (enricher_name, lat_rounded, lon_rounded, payload_json, cached_at)
+                VALUES (?, ?, ?, ?, ?)
+                ON CONFLICT (enricher_name, lat_rounded, lon_rounded) DO UPDATE SET
+                    payload_json = excluded.payload_json,
+                    cached_at = excluded.cached_at
+                """,
+                (enricher_name, lat_r, lon_r, json.dumps(payload), now_iso),
+            )
+            conn.commit()
+        finally:
+            conn.close()
+
+    def _is_expired(self, cached_at_iso: str) -> bool:
+        try:
+            cached_at = datetime.fromisoformat(cached_at_iso)
+        except ValueError:
+            return True
+        if cached_at.tzinfo is None:
+            cached_at = cached_at.replace(tzinfo=timezone.utc)
+        age_s = (datetime.now(timezone.utc) - cached_at).total_seconds()
+        return age_s > self._ttl_s
+
+    # --- async surface -----------------------------------------------------
+
+    async def get(self, enricher_name: str, lat: float, lon: float) -> dict[str, Any] | None:
+        """Return the cached bundle, or None on miss / expiry."""
+        return await asyncio.to_thread(self._get_sync, enricher_name, lat, lon)
+
+    async def set(
+        self, enricher_name: str, lat: float, lon: float, payload: dict[str, Any]
+    ) -> None:
+        """Cache a bundle (idempotent upsert on the rounded-coords key)."""
+        await asyncio.to_thread(self._set_sync, enricher_name, lat, lon, payload)
diff --git a/src/central/enrichment/geocoder.py b/src/central/enrichment/geocoder.py
new file mode 100644
index 0000000..ab75017
--- /dev/null
+++ b/src/central/enrichment/geocoder.py
@@ -0,0 +1,92 @@
+"""Reverse-geocoding enricher + the pluggable backend contract.
+
+GeocoderEnricher is the only enricher in PR J. It owns the cache + the
+all-null normalization; the actual lookup is delegated to a GeocoderBackend.
+PR J ships NoOpBackend only (all-null); real backends (Navi/Photon/Nominatim)
+land in PR K.
+"""
+
+import logging
+from typing import Any, Protocol, runtime_checkable
+
+from central.enrichment.cache import EnrichmentCache
+
+logger = logging.getLogger(__name__)
+
+# Locked canonical geocoder field set. The single source of truth for what a
+# geocoder enrichment bundle looks like — backends fill what they can and
+# return None for the rest; NoOpBackend returns all None.
+GEOCODER_FIELDS: tuple[str, ...] = (
+    "name",
+    "city",
+    "county",
+    "state",
+    "country",
+    "postal_code",
+    "timezone",
+    "landclass",
+    "elevation_m",
+)
+
+
+def all_null_bundle() -> dict[str, Any]:
+    """A geocoder bundle with every locked field present and None."""
+    return {field: None for field in GEOCODER_FIELDS}
+
+
+@runtime_checkable
+class GeocoderBackend(Protocol):
+    """The pluggable reverse-geocoding layer beneath GeocoderEnricher."""
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        """Return canonical geocoder fields (see GEOCODER_FIELDS).
+
+        Fields the backend can't resolve return None. Must never raise.
+        """
+        ...
+
+
+class GeocoderEnricher:
+    """Reverse-geocode a location into the canonical geocoder field set.
+
+    Resolution: cache hit -> return cached; cache miss -> call backend, cache
+    the (normalized) result even when all-null, return it. Backend failure
+    (any exception escaping the backend's "never raise" contract) -> return
+    all-null and DO NOT cache, so the next call retries.
+    """
+
+    name = "geocoder"
+
+    def __init__(
+        self,
+        backend: GeocoderBackend,
+        cache: EnrichmentCache | None = None,
+    ) -> None:
+        self._backend = backend
+        self._cache = cache
+
+    async def enrich(self, location: dict[str, float]) -> dict[str, Any]:
+        lat = location.get("lat")
+        lon = location.get("lon")
+        if lat is None or lon is None:
+            return all_null_bundle()
+
+        if self._cache is not None:
+            cached = await self._cache.get(self.name, lat, lon)
+            if cached is not None:
+                return cached
+
+        try:
+            raw = await self._backend.reverse(lat, lon)
+        except Exception:
+            # Backend broke its "never raise" contract. Return all-null and do
+            # NOT cache, so a transient failure doesn't get pinned for the TTL.
+            logger.exception("geocoder backend raised; returning all-null bundle")
+            return all_null_bundle()
+
+        # Normalize to the locked field set: every field present, extras dropped.
+        normalized = {field: raw.get(field) for field in GEOCODER_FIELDS}
+
+        if self._cache is not None:
+            await self._cache.set(self.name, lat, lon, normalized)
+        return normalized
diff --git a/src/central/gui/routes.py b/src/central/gui/routes.py
index a171c47..ef7ba49 100644
--- a/src/central/gui/routes.py
+++ b/src/central/gui/routes.py
@@ -51,6 +51,7 @@ from pathlib import Path
 from central.config_models import AdapterConfig
 from central.gui.db import get_pool
 from central.gui.form_descriptors import describe_fields, FieldDescriptor
+from central.api_key_resolver import adapter_has_resolved_api_key
 from central.adapter_discovery import discover_adapters
 from central.streams import STREAMS as STREAM_REGISTRY
 from pydantic import ValidationError
@@ -1348,16 +1349,13 @@ async def adapters_list(
             settings = row["settings"] or {}
             adapter_cls = adapter_classes.get(row["name"])
 
-            # Check if required API key is missing
-            api_key_missing = False
-            requires_api_key_alias = None
-            if adapter_cls and adapter_cls.requires_api_key is not None:
-                requires_api_key_alias = adapter_cls.requires_api_key
-                has_key = await conn.fetchval(
-                    "SELECT 1 FROM config.api_keys WHERE alias = $1",
-                    requires_api_key_alias,
-                )
-                api_key_missing = not has_key
+            # Check if required API key is missing — resolve via the per-row
+            # settings[api_key_field] (operator-selected alias), falling back
+            # to the class-attribute default when settings hasn't been set.
+            has_key, requires_api_key_alias = await adapter_has_resolved_api_key(
+                conn, adapter_cls, settings,
+            )
+            api_key_missing = not has_key
 
             adapters.append({
                 "name": row["name"],
@@ -1445,23 +1443,15 @@ async def adapters_edit_form(
                 if f.name == adapter_cls.api_key_field:
                     f.widget = "api_key_select"
 
-    # Fetch API keys for api_key_select widget
-    api_keys = []
+    # Fetch API keys for api_key_select widget + resolve the per-adapter
+    # alias against the operator-set settings, not the class-attr default.
     async with pool.acquire() as conn:
         api_key_rows = await conn.fetch("SELECT alias FROM config.api_keys ORDER BY alias")
         api_keys = [{"alias": r["alias"]} for r in api_key_rows]
-
-    # Check if required API key is missing
-    api_key_missing = False
-    requires_api_key_alias = None
-    if adapter_cls and adapter_cls.requires_api_key is not None:
-        requires_api_key_alias = adapter_cls.requires_api_key
-        async with pool.acquire() as conn:
-            has_key = await conn.fetchval(
-                "SELECT 1 FROM config.api_keys WHERE alias = $1",
-                requires_api_key_alias,
-            )
-            api_key_missing = not has_key
+        has_key, requires_api_key_alias = await adapter_has_resolved_api_key(
+            conn, adapter_cls, settings,
+        )
+        api_key_missing = not has_key
 
     # Generic settings-driven preview. Adapters opt in by overriding
     # SourceAdapter.preview_for_settings; the framework is duck-typed on the
@@ -1700,20 +1690,15 @@ async def adapters_edit_submit(
                         if f.name == adapter_cls.api_key_field:
                             f.widget = "api_key_select"
 
-            # Fetch API keys for api_key_select widget
+            # Fetch API keys for api_key_select widget + resolve the per-adapter
+            # alias against the pre-edit settings (form validation failed, so
+            # the stored settings haven't been replaced).
             api_key_rows = await conn.fetch("SELECT alias FROM config.api_keys ORDER BY alias")
             api_keys = [{"alias": r["alias"]} for r in api_key_rows]
-
-            # Check if required API key is missing
-            api_key_missing = False
-            requires_api_key_alias = None
-            if adapter_cls and adapter_cls.requires_api_key is not None:
-                requires_api_key_alias = adapter_cls.requires_api_key
-                has_key = await conn.fetchval(
-                    "SELECT 1 FROM config.api_keys WHERE alias = $1",
-                    requires_api_key_alias,
-                )
-                api_key_missing = not has_key
+            has_key, requires_api_key_alias = await adapter_has_resolved_api_key(
+                conn, adapter_cls, current_settings,
+            )
+            api_key_missing = not has_key
 
             csrf_token = request.state.csrf_token
             response = templates.TemplateResponse(
diff --git a/src/central/supervisor.py b/src/central/supervisor.py
index bdc68e6..8ca6be9 100644
--- a/src/central/supervisor.py
+++ b/src/central/supervisor.py
@@ -20,9 +20,66 @@ from central.config_models import AdapterConfig
 from central.config_source import ConfigSource, DbConfigSource
 from central.config_store import ConfigStore
 from central.bootstrap_config import get_settings
+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.no_op import NoOpBackend
+from central.enrichment.geocoder import GeocoderEnricher
+from central.models import Event
 from central.stream_manager import StreamManager
 from central.streams import STREAMS as STREAM_REGISTRY
 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}
+
+
+def build_enrichers(
+    enrichment_config: EnrichmentConfig,
+    cache_db_path: Path = ENRICHMENT_CACHE_DB_PATH,
+) -> list[Enricher]:
+    """Instantiate the configured enricher(s) with their backend + cache.
+
+    Read once at supervisor startup — enrichment config is NOT hot-reloaded
+    in PR J (see EnrichmentConfig docstring).
+    """
+    backend_cls = _BACKEND_REGISTRY[enrichment_config.backend_class]
+    backend = backend_cls(**enrichment_config.backend_settings)
+    cache = EnrichmentCache(cache_db_path, ttl_s=enrichment_config.cache_ttl_s)
+    enricher_cls = _ENRICHER_REGISTRY[enrichment_config.enricher_class]
+    return [enricher_cls(backend, cache=cache)]
+
+
+async def apply_enrichment(
+    event: Event,
+    enrichment_locations: list[tuple[str, str]],
+    enrichers: list[Enricher],
+) -> None:
+    """Attach enrichment results to event.data["_enriched"] in place.
+
+    No-op when the adapter declares no enrichment_locations or no enrichers
+    are registered. Uses the first (lat_path, lon_path) tuple that resolves to
+    a non-null coordinate pair in event.data. Each enricher's result is keyed
+    by enricher.name. Mutates the data dict in place (Event is frozen, but its
+    data dict is not — this avoids a model_copy on every published event).
+    """
+    if not enrichment_locations or not enrichers:
+        return
+    for lat_path, lon_path in enrichment_locations:
+        lat = event.data.get(lat_path)
+        lon = event.data.get(lon_path)
+        if lat is None or lon is None:
+            continue
+        location = {"lat": float(lat), "lon": float(lon)}
+        enriched: dict[str, Any] = {}
+        for enricher in enrichers:
+            enriched[enricher.name] = await enricher.enrich(location)
+        event.data["_enriched"] = enriched
+        return
 
 # Stream subject mappings -- derived from the registry; every stream is included
 # (META too: supervisor must create it in JetStream even though archive skips it).
@@ -95,11 +152,16 @@ class Supervisor:
         config_store: ConfigStore,
         nats_url: str,
         cloudevents_config: Any = None,
+        enrichment_config: EnrichmentConfig | None = None,
     ) -> None:
         self._config_source = config_source
         self._config_store = config_store
         self._nats_url = nats_url
         self._cloudevents_config = cloudevents_config
+        # Enrichment is read once at startup (no hot-reload in PR J).
+        self._enrichers: list[Enricher] = build_enrichers(
+            enrichment_config or EnrichmentConfig()
+        )
         self._adapters = discover_adapters()
         self._nc: nats.NATS | None = None
         self._js: JetStreamContext | None = None
@@ -216,6 +278,16 @@ class Supervisor:
                         state.adapter.bump_last_seen(event.id)
                         continue
 
+                    # Enrichment (no-op unless the adapter declares
+                    # enrichment_locations). Runs after dedup so we don't
+                    # enrich events we'd skip, and before wrap_event so the
+                    # _enriched block lands in the published payload.
+                    await apply_enrichment(
+                        event,
+                        state.adapter.enrichment_locations,
+                        self._enrichers,
+                    )
+
                     # Build CloudEvent (uses defaults if no config provided)
                     envelope, msg_id = wrap_event(event, self._cloudevents_config)
 
@@ -263,10 +335,13 @@ class Supervisor:
         If the adapter was previously stopped (state exists but task is not running),
         reuses the existing state to preserve last_completed_poll for rate limiting.
         """
-        # API key precondition
+        # API key precondition — resolve via per-row settings[api_key_field]
+        # (operator-selected alias), falling back to the class-attribute
+        # default when settings hasn't been set. Returns None when no key
+        # is required.
         adapter_cls = self._adapters.get(config.name)
-        if adapter_cls is not None and adapter_cls.requires_api_key is not None:
-            alias = adapter_cls.requires_api_key
+        alias = resolve_api_key_alias(adapter_cls, config.settings)
+        if alias is not None:
             key_value = await self._config_store.get_api_key(alias)
             if not key_value:
                 error_msg = f"missing api key: {alias}"
@@ -760,6 +835,9 @@ async def async_main() -> None:
         nats_url=settings.nats_url,
         # CloudEvents uses protocol-level defaults from cloudevents_constants
         cloudevents_config=None,
+        # Enrichment defaults: GeocoderEnricher + NoOpBackend (all-null). Read
+        # once here at startup; PR K wires real backends + DB-backed config.
+        enrichment_config=EnrichmentConfig(),
     )
     logger.info(
         "CloudEvents config: defaults",
diff --git a/tests/test_adapters.py b/tests/test_adapters.py
index aa3cd90..8ed0259 100644
--- a/tests/test_adapters.py
+++ b/tests/test_adapters.py
@@ -452,8 +452,17 @@ class TestAdaptersJsonbRegression:
             {"alias": "firms_key"},
             {"alias": "other_key"},
         ])
+        # The /adapters/{name} edit handler also issues a fetchval against
+        # config.api_keys to resolve whether the adapter's key is present.
+        # Return 1 (truthy) so the handler proceeds — this test only asserts
+        # api_keys reaches the template context, not the warning state.
+        mock_conn.fetchval = AsyncMock(return_value=1)
         mock_conn.__aenter__ = AsyncMock(return_value=mock_conn)
-        mock_conn.__aexit__ = AsyncMock()
+        # AsyncMock() with no return_value yields a MagicMock — which is truthy,
+        # and the async context manager protocol reads a truthy __aexit__ return
+        # as "exception suppressed." That silently swallows any error inside the
+        # `async with` block. Pin return_value=None so exceptions propagate.
+        mock_conn.__aexit__ = AsyncMock(return_value=None)
 
         mock_pool = MagicMock()
         mock_pool.acquire = MagicMock(return_value=mock_conn)
diff --git a/tests/test_api_key_resolver.py b/tests/test_api_key_resolver.py
new file mode 100644
index 0000000..a137f5b
--- /dev/null
+++ b/tests/test_api_key_resolver.py
@@ -0,0 +1,249 @@
+"""Tests for central.gui._api_key_resolver.adapter_has_resolved_api_key.
+
+The /adapters list, /adapters/{name} edit, and POST error re-render flows
+previously inlined a predicate that compared the SourceAdapter class
+attribute `requires_api_key` (default literal string) against
+`config.api_keys` — ignoring the per-row `settings[api_key_field]` alias
+the operator actually selected. The helper consolidates the resolution
+logic; these tests pin it.
+
+No hardcoded adapter-name list literals: keyless-adapter case picks a
+real one via central.adapter_discovery. The settings-driven cases use
+inline minimal SourceAdapter subclasses because no live adapter today
+has the pertinent class-attr/field combinations.
+"""
+
+from collections.abc import AsyncIterator
+from typing import Any
+
+import pytest
+from pydantic import BaseModel
+
+from central.adapter import SourceAdapter
+from central.adapter_discovery import discover_adapters
+from central.api_key_resolver import (
+    adapter_has_resolved_api_key,
+    resolve_api_key_alias,
+)
+from central.models import Event
+
+
+class _FakeConn:
+    """Captures the (sql, alias) of each fetchval call and returns a scripted
+    result. Mirrors the asyncpg connection surface adapter_has_resolved_api_key
+    actually uses."""
+
+    def __init__(self, result: Any) -> None:
+        self.result = result
+        self.calls: list[tuple[str, tuple[Any, ...]]] = []
+
+    async def fetchval(self, sql: str, *params: Any) -> Any:
+        self.calls.append((sql, params))
+        return self.result
+
+
+def _pick_keyless_adapter() -> type[SourceAdapter] | None:
+    """First discovered adapter with requires_api_key is None.
+
+    Lets test 1 exercise the no-SQL short-circuit against a real subclass
+    without hardcoding the adapter's name.
+    """
+    for cls in discover_adapters().values():
+        if cls.requires_api_key is None:
+            return cls
+    return None
+
+
+class _BareKeyAdapter(SourceAdapter):
+    """Requires a key but does NOT expose an operator-overridable field.
+
+    Forces the helper to fall back to the class-attribute default.
+    """
+
+    name = "_bare_key"
+    display_name = "_BareKey"
+    description = "Test fixture: class-attr fallback path."
+    settings_schema = BaseModel
+    requires_api_key = "default"
+    api_key_field = None
+    default_cadence_s = 60
+
+    async def poll(self) -> AsyncIterator[Event]:  # pragma: no cover
+        if False:
+            yield  # type: ignore[unreachable]
+        return
+
+    async def apply_config(self, new_config) -> None:  # pragma: no cover
+        pass
+
+    def subject_for(self, event: Event) -> str:  # pragma: no cover
+        return "central.test._bare_key"
+
+
+class _OperatorOverridableAdapter(SourceAdapter):
+    """Requires a key AND exposes an operator-overridable alias field.
+
+    Models the FIRMS-shaped contract that previously misfired.
+    """
+
+    name = "_overridable"
+    display_name = "_Overridable"
+    description = "Test fixture: operator-overridable alias field."
+    settings_schema = BaseModel
+    requires_api_key = "default"
+    api_key_field = "api_key_alias"
+    default_cadence_s = 60
+
+    async def poll(self) -> AsyncIterator[Event]:  # pragma: no cover
+        if False:
+            yield  # type: ignore[unreachable]
+        return
+
+    async def apply_config(self, new_config) -> None:  # pragma: no cover
+        pass
+
+    def subject_for(self, event: Event) -> str:  # pragma: no cover
+        return "central.test._overridable"
+
+
+@pytest.mark.asyncio
+async def test_keyless_adapter_short_circuits_without_sql():
+    """An adapter with requires_api_key=None returns (True, None) and the
+    helper issues NO SQL — caller can assume the gate is open."""
+    keyless = _pick_keyless_adapter()
+    if keyless is None:
+        pytest.skip("no keyless adapter discovered in central.adapters")
+    conn = _FakeConn(result=1)
+    has_key, alias = await adapter_has_resolved_api_key(conn, keyless, {})
+    assert (has_key, alias) == (True, None)
+    assert conn.calls == [], "no SQL expected for keyless adapter"
+
+
+@pytest.mark.asyncio
+async def test_class_attr_fallback_when_no_api_key_field():
+    """Adapter exposes requires_api_key but no api_key_field — helper falls
+    back to the class-attribute default for the lookup alias."""
+    conn = _FakeConn(result=1)
+    has_key, alias = await adapter_has_resolved_api_key(conn, _BareKeyAdapter, {})
+    assert alias == "default"
+    assert has_key is True
+    assert len(conn.calls) == 1
+    sql, params = conn.calls[0]
+    assert "config.api_keys" in sql
+    assert params == ("default",)
+
+
+@pytest.mark.asyncio
+async def test_settings_override_takes_precedence_over_class_attr():
+    """Operator-selected alias in settings[api_key_field] wins over the
+    class-attribute default. Regression guard for the FIRMS-shaped bug:
+    requires_api_key='default' but operator stored a key under 'custom'."""
+    conn = _FakeConn(result=1)
+    settings = {"api_key_alias": "custom"}
+    has_key, alias = await adapter_has_resolved_api_key(
+        conn, _OperatorOverridableAdapter, settings,
+    )
+    assert alias == "custom", "operator-selected alias should win"
+    assert has_key is True
+    assert conn.calls[0][1] == ("custom",), (
+        f"SQL must query the operator-selected alias, got {conn.calls[0][1]!r}"
+    )
+
+
+@pytest.mark.asyncio
+async def test_missing_settings_field_falls_back_to_class_attr():
+    """Operator hasn't visited the form yet — settings dict lacks the
+    api_key_field entry. Class-attr default is the safe fallback."""
+    conn = _FakeConn(result=1)
+    has_key, alias = await adapter_has_resolved_api_key(
+        conn, _OperatorOverridableAdapter, {"unrelated": "noise"},
+    )
+    assert alias == "default"
+    assert conn.calls[0][1] == ("default",)
+
+    # Same path when settings is None entirely.
+    conn2 = _FakeConn(result=1)
+    has_key2, alias2 = await adapter_has_resolved_api_key(
+        conn2, _OperatorOverridableAdapter, None,
+    )
+    assert alias2 == "default"
+    assert conn2.calls[0][1] == ("default",)
+
+
+@pytest.mark.asyncio
+async def test_empty_string_settings_field_falls_back_to_class_attr():
+    """Empty string in settings does NOT mean "look up alias '' "; it means
+    "not set, use default" — same shape the form parser yields for cleared
+    text inputs."""
+    conn = _FakeConn(result=1)
+    has_key, alias = await adapter_has_resolved_api_key(
+        conn, _OperatorOverridableAdapter, {"api_key_alias": "   "},
+    )
+    assert alias == "default", "whitespace-only must fall through to class attr"
+    assert conn.calls[0][1] == ("default",)
+
+    conn2 = _FakeConn(result=1)
+    has_key2, alias2 = await adapter_has_resolved_api_key(
+        conn2, _OperatorOverridableAdapter, {"api_key_alias": ""},
+    )
+    assert alias2 == "default"
+    assert conn2.calls[0][1] == ("default",)
+
+
+@pytest.mark.asyncio
+async def test_resolved_alias_absent_returns_has_key_false():
+    """If the resolved alias has no matching row, helper returns
+    (False, alias) so caller renders the warning chip with the right alias
+    shown in the title attribute."""
+    conn = _FakeConn(result=None)
+    has_key, alias = await adapter_has_resolved_api_key(
+        conn, _OperatorOverridableAdapter, {"api_key_alias": "ghost"},
+    )
+    assert (has_key, alias) == (False, "ghost")
+
+
+@pytest.mark.asyncio
+async def test_unknown_adapter_cls_short_circuits():
+    """Row references a deleted adapter — adapter_cls is None. Helper must
+    not crash, must not issue SQL, and must report no missing key (the warning
+    is for known adapters; orphaned rows are a separate concern)."""
+    conn = _FakeConn(result=None)
+    has_key, alias = await adapter_has_resolved_api_key(conn, None, {})
+    assert (has_key, alias) == (True, None)
+    assert conn.calls == []
+
+
+# ---------------------------------------------------------------------------
+# Supervisor uses the sync resolver directly (no DB round-trip — supervisor
+# has its own ConfigStore and calls get_api_key on the resolved alias).
+# These tests mirror the route coverage on the sync entry point.
+# ---------------------------------------------------------------------------
+
+
+def test_supervisor_uses_operator_selected_alias():
+    """Supervisor's adapter-start precondition must resolve to the same alias
+    the GUI's warning predicate resolves to. Regression guard for the second
+    half of the FIRMS-shaped bug: routes opened the gate but supervisor still
+    refused to start with `missing api key: <class_attr>`."""
+    alias = resolve_api_key_alias(
+        _OperatorOverridableAdapter, {"api_key_alias": "firms_production"},
+    )
+    assert alias == "firms_production"
+
+
+def test_supervisor_falls_back_to_class_attr_when_settings_unset():
+    """Operator hasn't touched settings yet — supervisor still finds the
+    class-attribute default (preserves pre-bug behavior for fresh installs)."""
+    assert resolve_api_key_alias(_OperatorOverridableAdapter, None) == "default"
+    assert resolve_api_key_alias(_OperatorOverridableAdapter, {}) == "default"
+    assert resolve_api_key_alias(_BareKeyAdapter, {}) == "default"
+
+
+def test_supervisor_returns_none_for_keyless_adapter():
+    """When the adapter doesn't need a key, supervisor should skip the
+    `get_api_key` call entirely — the sync resolver returns None to signal."""
+    keyless = _pick_keyless_adapter()
+    if keyless is None:
+        pytest.skip("no keyless adapter discovered in central.adapters")
+    assert resolve_api_key_alias(keyless, {}) is None
+    assert resolve_api_key_alias(None, {}) is None
diff --git a/tests/test_enrichment_framework.py b/tests/test_enrichment_framework.py
new file mode 100644
index 0000000..98ac7c9
--- /dev/null
+++ b/tests/test_enrichment_framework.py
@@ -0,0 +1,160 @@
+"""Tests for the enrichment cache + framework wiring.
+
+Covers cache hit/miss/TTL/rounding, idempotent concurrent writes, and the
+"backend failure -> all-null, not cached" contract via GeocoderEnricher.
+"""
+
+import asyncio
+import json
+import sqlite3
+from pathlib import Path
+from typing import Any
+
+import pytest
+
+from central.enrichment.cache import EnrichmentCache, round_coord
+from central.enrichment.geocoder import GEOCODER_FIELDS, GeocoderEnricher, all_null_bundle
+
+
+@pytest.fixture
+def cache_path(tmp_path: Path) -> Path:
+    return tmp_path / "nested" / "enrichment_cache.db"
+
+
+def test_init_creates_parent_dir_and_table(cache_path: Path):
+    assert not cache_path.parent.exists()
+    cache = EnrichmentCache(cache_path, ttl_s=60)
+    assert cache_path.parent.is_dir()
+    # Table exists and is queryable.
+    conn = sqlite3.connect(cache_path)
+    try:
+        cur = conn.execute(
+            "SELECT name FROM sqlite_master WHERE type='table' AND name='enrichment_cache'"
+        )
+        assert cur.fetchone() is not None
+    finally:
+        conn.close()
+
+
+@pytest.mark.asyncio
+async def test_cache_miss_then_hit(cache_path: Path):
+    cache = EnrichmentCache(cache_path, ttl_s=3600)
+    assert await cache.get("geocoder", 45.0, -116.0) is None  # miss
+    payload = {"name": "Somewhere", "state": "ID"}
+    await cache.set("geocoder", 45.0, -116.0, payload)
+    hit = await cache.get("geocoder", 45.0, -116.0)
+    assert hit == payload
+
+
+@pytest.mark.asyncio
+async def test_ttl_expiry_returns_miss(cache_path: Path):
+    cache = EnrichmentCache(cache_path, ttl_s=0)  # everything immediately stale
+    await cache.set("geocoder", 1.0, 2.0, {"name": "x"})
+    # ttl_s=0 -> age (>0) always exceeds ttl -> treated as expired.
+    assert await cache.get("geocoder", 1.0, 2.0) is None
+
+
+def test_round_coord_4dp():
+    assert round_coord(45.123456789) == 45.1235
+    assert round_coord(-116.000049) == -116.0
+    assert round_coord(12.99995) == 13.0
+
+
+@pytest.mark.asyncio
+async def test_rounding_collapses_nearby_coords_to_same_key(cache_path: Path):
+    cache = EnrichmentCache(cache_path, ttl_s=3600)
+    await cache.set("geocoder", 45.12341, -116.45678, {"name": "rounded"})
+    # 45.123413 / -116.456784 round to the same 4dp key -> same row.
+    hit = await cache.get("geocoder", 45.123413, -116.456784)
+    assert hit == {"name": "rounded"}
+
+
+@pytest.mark.asyncio
+async def test_concurrent_sets_do_not_double_write(cache_path: Path):
+    cache = EnrichmentCache(cache_path, ttl_s=3600)
+    await asyncio.gather(
+        *[cache.set("geocoder", 10.0, 20.0, {"n": i}) for i in range(20)]
+    )
+    conn = sqlite3.connect(cache_path)
+    try:
+        count = conn.execute(
+            "SELECT COUNT(*) FROM enrichment_cache WHERE enricher_name='geocoder' "
+            "AND lat_rounded=? AND lon_rounded=?",
+            (10.0, 20.0),
+        ).fetchone()[0]
+    finally:
+        conn.close()
+    assert count == 1, "PRIMARY KEY must collapse concurrent writes to one row"
+
+
+class _CountingBackend:
+    """Backend that counts reverse() calls; lets tests prove cache hits."""
+
+    def __init__(self) -> None:
+        self.calls = 0
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        self.calls += 1
+        return {**all_null_bundle(), "name": "Counted", "state": "ID"}
+
+
+class _ExplodingBackend:
+    """Backend that violates the never-raise contract."""
+
+    def __init__(self) -> None:
+        self.calls = 0
+
+    async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+        self.calls += 1
+        raise RuntimeError("upstream geocoder down")
+
+
+@pytest.mark.asyncio
+async def test_backend_failure_returns_all_null_and_does_not_cache(cache_path: Path):
+    cache = EnrichmentCache(cache_path, ttl_s=3600)
+    backend = _ExplodingBackend()
+    enricher = GeocoderEnricher(backend, cache=cache)
+
+    result = await enricher.enrich({"lat": 5.0, "lon": 6.0})
+    assert result == all_null_bundle()
+
+    # Nothing cached -> a second call retries the backend (calls increments).
+    assert await cache.get("geocoder", 5.0, 6.0) is None
+    await enricher.enrich({"lat": 5.0, "lon": 6.0})
+    assert backend.calls == 2, "failed lookups must not be cached (must retry)"
+
+
+@pytest.mark.asyncio
+async def test_successful_result_is_cached_and_avoids_second_backend_call(cache_path: Path):
+    cache = EnrichmentCache(cache_path, ttl_s=3600)
+    backend = _CountingBackend()
+    enricher = GeocoderEnricher(backend, cache=cache)
+
+    first = await enricher.enrich({"lat": 7.5, "lon": 8.5})
+    second = await enricher.enrich({"lat": 7.5, "lon": 8.5})
+    assert first == second
+    assert backend.calls == 1, "second call with same coords must hit cache"
+
+
+@pytest.mark.asyncio
+async def test_all_null_result_is_cached(cache_path: Path):
+    """A backend that resolves nothing still gets cached — the contract says
+    cache even all-null so we don't re-hammer the backend for known-empty
+    coordinates."""
+
+    class _NullCounting:
+        def __init__(self) -> None:
+            self.calls = 0
+
+        async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+            self.calls += 1
+            return all_null_bundle()
+
+    cache = EnrichmentCache(cache_path, ttl_s=3600)
+    backend = _NullCounting()
+    enricher = GeocoderEnricher(backend, cache=cache)
+    await enricher.enrich({"lat": 1.0, "lon": 1.0})
+    await enricher.enrich({"lat": 1.0, "lon": 1.0})
+    assert backend.calls == 1
+    cached = await cache.get("geocoder", 1.0, 1.0)
+    assert cached == all_null_bundle()
diff --git a/tests/test_firms.py b/tests/test_firms.py
index bfe629a..2ab1e1d 100644
--- a/tests/test_firms.py
+++ b/tests/test_firms.py
@@ -421,3 +421,58 @@ class TestApplyConfig:
         assert adapter._satellites == ["VIIRS_NOAA20_NRT"]
 
         await adapter.shutdown()
+
+
+class TestEnrichmentIntegration:
+    """FIRMS is the PR J enrichment pilot."""
+
+    def test_enrichment_locations_declared_and_resolvable(self, temp_db_path, mock_config_store):
+        """FIRMS declares enrichment_locations and the declared paths actually
+        resolve to coordinates in a real event's data — verified structurally,
+        not by hardcoding the literal tuple."""
+        locations = getattr(FIRMSAdapter, "enrichment_locations")
+        assert isinstance(locations, list) and len(locations) >= 1
+        for tup in locations:
+            assert isinstance(tup, tuple) and len(tup) == 2
+            assert all(isinstance(p, str) for p in tup)
+
+        config = make_adapter_config()
+        adapter = FIRMSAdapter(
+            config=config,
+            config_store=mock_config_store,
+            cursor_db_path=temp_db_path,
+        )
+        rows = adapter._parse_csv(SAMPLE_CSV, "VIIRS_SNPP_NRT")
+        event = adapter._row_to_event(rows[0], "VIIRS_SNPP_NRT")
+        # Every declared (lat_path, lon_path) must resolve to a float in data.
+        for lat_path, lon_path in locations:
+            assert isinstance(event.data.get(lat_path), float)
+            assert isinstance(event.data.get(lon_path), float)
+
+    @pytest.mark.asyncio
+    async def test_event_passes_through_supervisor_enrichment(
+        self, tmp_path, temp_db_path, mock_config_store
+    ):
+        """A FIRMS event run through the supervisor's enrichment stage emerges
+        with data._enriched.geocoder populated (all-null under NoOpBackend)."""
+        from central.config_models import EnrichmentConfig
+        from central.enrichment.geocoder import all_null_bundle
+        from central.supervisor import apply_enrichment, build_enrichers
+
+        config = make_adapter_config()
+        adapter = FIRMSAdapter(
+            config=config,
+            config_store=mock_config_store,
+            cursor_db_path=temp_db_path,
+        )
+        rows = adapter._parse_csv(SAMPLE_CSV, "VIIRS_SNPP_NRT")
+        event = adapter._row_to_event(rows[0], "VIIRS_SNPP_NRT")
+        assert "_enriched" not in event.data
+
+        enrichers = build_enrichers(
+            EnrichmentConfig(), cache_db_path=tmp_path / "enrichment_cache.db"
+        )
+        await apply_enrichment(event, adapter.enrichment_locations, enrichers)
+
+        assert "_enriched" in event.data
+        assert event.data["_enriched"]["geocoder"] == all_null_bundle()
diff --git a/tests/test_geocoder_enricher.py b/tests/test_geocoder_enricher.py
new file mode 100644
index 0000000..df0e1fc
--- /dev/null
+++ b/tests/test_geocoder_enricher.py
@@ -0,0 +1,65 @@
+"""Tests for GeocoderEnricher with the default NoOpBackend."""
+
+from typing import Any
+
+import pytest
+
+from central.enrichment.backends.no_op import NoOpBackend
+from central.enrichment.cache import EnrichmentCache
+from central.enrichment.geocoder import (
+    GEOCODER_FIELDS,
+    GeocoderEnricher,
+    all_null_bundle,
+)
+
+
+@pytest.mark.asyncio
+async def test_noop_backend_returns_all_null_bundle():
+    enricher = GeocoderEnricher(NoOpBackend())
+    result = await enricher.enrich({"lat": 45.0, "lon": -116.0})
+    assert result == all_null_bundle()
+    assert all(v is None for v in result.values())
+
+
+@pytest.mark.asyncio
+async def test_field_set_matches_locked_protocol():
+    """Every field in the locked GEOCODER_FIELDS set is present (all None for
+    NoOpBackend), and no extra keys leak through — bidirectional equality."""
+    enricher = GeocoderEnricher(NoOpBackend())
+    result = await enricher.enrich({"lat": 1.0, "lon": 2.0})
+    assert set(result.keys()) == set(GEOCODER_FIELDS)
+
+
+@pytest.mark.asyncio
+async def test_missing_coords_returns_all_null_without_backend_call():
+    class _Tripwire:
+        async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+            raise AssertionError("backend must not be called for null coords")
+
+    enricher = GeocoderEnricher(_Tripwire())
+    assert await enricher.enrich({"lat": None, "lon": None}) == all_null_bundle()  # type: ignore[dict-item]
+    assert await enricher.enrich({}) == all_null_bundle()
+
+
+@pytest.mark.asyncio
+async def test_enricher_name_is_geocoder():
+    """The name keys the result under event.data['_enriched'][name]."""
+    assert GeocoderEnricher(NoOpBackend()).name == "geocoder"
+
+
+@pytest.mark.asyncio
+async def test_sequential_calls_same_coords_hit_cache(tmp_path):
+    class _CountingNoOp:
+        def __init__(self) -> None:
+            self.calls = 0
+
+        async def reverse(self, lat: float, lon: float) -> dict[str, Any]:
+            self.calls += 1
+            return all_null_bundle()
+
+    cache = EnrichmentCache(tmp_path / "c.db", ttl_s=3600)
+    backend = _CountingNoOp()
+    enricher = GeocoderEnricher(backend, cache=cache)
+    for _ in range(5):
+        await enricher.enrich({"lat": 33.5, "lon": -111.9})
+    assert backend.calls == 1, "repeated identical coords must collapse to one backend call"