chore: establish local platform baseline

migrations/000035_external_dependency_probe_state.up.sql

@@ -0,0 +1,25 @@
+BEGIN;
+
+CREATE TABLE external_dependency_probe_state (
+    service_name          varchar(32) NOT NULL CHECK (service_name ~ '^[a-z][a-z0-9-]{1,31}$'),
+    dependency            varchar(64) NOT NULL CHECK (dependency ~ '^[a-z][a-z0-9_]{1,63}$'),
+    status                varchar(16) NOT NULL CHECK (status IN ('AVAILABLE','UNAVAILABLE')),
+    checked_at            timestamptz NOT NULL,
+    last_success_at       timestamptz,
+    last_failure_at       timestamptz,
+    last_error_code       varchar(80),
+    latency_ms            bigint NOT NULL CHECK (latency_ms >= 0),
+    probe_interval_ms     bigint NOT NULL CHECK (probe_interval_ms > 0),
+    consecutive_failures  integer NOT NULL DEFAULT 0 CHECK (consecutive_failures >= 0),
+    updated_at            timestamptz NOT NULL DEFAULT now(),
+    PRIMARY KEY (service_name, dependency),
+    CONSTRAINT external_probe_success_check CHECK (
+        (status='AVAILABLE' AND last_success_at IS NOT NULL AND last_error_code IS NULL AND consecutive_failures=0) OR
+        (status='UNAVAILABLE' AND last_failure_at IS NOT NULL AND last_error_code IS NOT NULL AND consecutive_failures>0)
+    )
+);
+
+CREATE INDEX external_dependency_probe_status_idx
+    ON external_dependency_probe_state(status, checked_at DESC);
+
+COMMIT;