better cache

openspec/specs/cache-layer/spec.md

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+## Purpose
+
+Provide a shared caching layer (Redis-backed) for ingestion and content processing flows, with TTL-based invalidation and manual cache clearing.
+
+## ADDED Requirements
+
+### Requirement: Redis-backed cache service
+The system MUST provide a Redis-backed cache service for use by ingestion and content processing flows.
+
+The cache service MUST be runnable in local development via Docker Compose.
+
+#### Scenario: Cache service available in Docker
+- **WHEN** the Docker Compose stack is started
+- **THEN** a Redis service is available to other services/scripts on the internal network
+
+### Requirement: TTL-based invalidation
+Cached entries MUST support TTL-based invalidation.
+
+The system MUST define a default TTL and MUST allow overriding the TTL via environment/config.
+
+#### Scenario: Default TTL applies
+- **WHEN** a cached entry is written without an explicit TTL override
+- **THEN** it expires after the configured default TTL
+
+#### Scenario: TTL override applies
+- **WHEN** a TTL override is configured via environment/config
+- **THEN** new cached entries use that TTL for expiration
+
+### Requirement: Cache key namespace
+Cache keys MUST be namespaced by source and parameters so that different data requests do not collide.
+
+#### Scenario: Two different sources do not collide
+- **WHEN** the system caches a YouTube fetch and a WordPress fetch
+- **THEN** they use different key namespaces and do not overwrite each other
+
+### Requirement: Manual cache clear
+The system MUST provide a script/command to manually clear the cache.
+
+#### Scenario: Manual clear executed
+- **WHEN** a developer runs the cache clear command
+- **THEN** the cache is cleared and subsequent ingestion runs produce cache misses
+