[Bug]: Semantic Cache guardrail can be saved/deployed without required embedding config, crashing the entire proxy

[randilt]

Please select the area the issue is related to

AI Workspace, Gateway

Please select the aspect the issue is related to

Aspect/UX (User experience, flows, usability, clarity), Aspect/Configuration (Config files, settings, env vars, defaults)

Description

The Semantic Cache guardrail's Console UI only exposes similarityThreshold, jsonPath, and streamingJsonPath.

Per semantic cache policy's own docs (https://wso2.com/api-platform/policy-hub/policies/semantic-cache), this policy also requires embedding provider / vector DB settings (embedding_provider_dimension, embedding_provider_api_key, etc.) set in the gateway's config.toml — but the UI never mentions this, and lets you save/deploy without it, with no warning.

At runtime, the policy fails to build (missing config keys), and this crashes policy chain construction for the entire proxy — not just caching-related traffic. Every route/method on the proxy returns a generic 500 Internal Server Error with no useful detail; the real cause is only visible in gateway logs.

Steps to Reproduce

1. Create an App LLM Proxy on a self-hosted gateway with no embedding provider / vector DB config in config.toml.
2. Guardrails & Policies → Add → Semantic Cache → leave all fields at default → Save.
3. Deploy — succeeds with no errors/warnings.
4. Invoke any resource on the proxy:

   curl -k -X POST "https://<gateway-host>:8443/<proxy-context>/<any-path>" \
     -H "X-API-Key: <valid proxy key>" -H "Content-Type: application/json" -d '{...}'

→ {"error":"Internal Server Error"}, HTTP 500, on every route/method.
5. Gateway runtime logs show:

   level=ERROR msg="Failed to build policy chain for route, skipping" ... error="... failed to resolve config for key \"embeddingDimension\": ... CEL evaluation error: no such key: embedding_provider_dimension"
   level=ERROR msg="Policy chain not found for route, returning 500" route=POST|/<proxy-context>/*|*

repeated for every route/method on the proxy.

Severity Level of the Issue

Severity/Blocker (Core functionality is broken and consumer is blocked. Need immediate attention)

Environment Details (with versions)

• ghcr.io/wso2/api-platform/ai-workspace:1.1.0-SNAPSHOT
• ghcr.io/wso2/api-platform/gateway-runtime:1.1.0
• ghcr.io/wso2/api-platform/gateway-controller:1.1.0
• Self-hosted gateway, local Docker setup, macOS host
• curl 8.7.1