fix(worker-ai-health): address feedback on health status and cache handling

- Add checks for 'not_configured' and 'unavailable' states in Snapshot#status
- Include PDF probe failure codes in failure_codes detection
- Fix cache lifetime extension by removing expires_in and filtering expired entries in recent()

Ensures unconfigured workers and missing PDF pipelines are marked as failing,
and stale cache entries don't get indefinite TTL refreshes.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A9494Pxh4LZKnNLTGfFXPw

app/jobs/worker_ai_health_check_job.rb

@@ -52,6 +52,8 @@ class WorkerAiHealthCheckJob < ApplicationJob
       [
         ai_health.llm_probe.failure_code,
         ai_health.function_calling_probe.failure_code,
+        ai_health.pdf_text_extraction_probe.failure_code,
+        ai_health.pdf_vision_processing_probe.failure_code,
         ai_health.vector_store_probe.failure_code,
         ai_health.embedding_probe.failure_code
       ].compact.uniq

app/models/worker_ai_health.rb

@@ -58,8 +58,8 @@ class WorkerAiHealth
     def status
       return :stale if stale?
       return :failing if failure_codes.present?
-      return :failing if llm_status == :failing || vector_store_status == :failing
-      return :failing if function_calling_status.in?(%i[unsupported failing])
+      return :failing if llm_status.in?(%i[not_configured failing]) || vector_store_status.in?(%i[not_configured failing])
+      return :failing if function_calling_status.in?(%i[unavailable unsupported failing])
 
       :passing
     end
@@ -100,7 +100,8 @@ class WorkerAiHealth
     def record!(snapshot, cache: Rails.cache)
       results = recent(cache: cache).reject { |r| r.process_identity == snapshot.process_identity }
       results = [ snapshot, *results ].first(MAX_RESULTS)
-      cache.write(CACHE_KEY, results, expires_in: RETENTION)
+      # Don't set expires_in here; let individual entries expire via checked_at time
+      cache.write(CACHE_KEY, results)
       snapshot
     end
 
@@ -109,7 +110,10 @@ class WorkerAiHealth
     # STALE_AFTER are still returned (status: :stale) so an operator can see
     # a worker went quiet rather than the section going empty.
     def recent(cache: Rails.cache)
-      Array(cache.read(CACHE_KEY)).sort_by { |r| r.checked_at || Time.at(0) }.reverse
+      results = Array(cache.read(CACHE_KEY))
+      # Filter out entries older than RETENTION
+      results = results.select { |r| r.checked_at && r.checked_at > RETENTION.ago }
+      results.sort_by { |r| r.checked_at || Time.at(0) }.reverse
     end
 
     # Stable identity for "this OS process" -- hostname:pid. Good enough to