Builds on PR-1 (#2729). Implements every endpoint in the OpenAPI spec
plus two operational concerns the agent never sees:
1. Capability negotiation. Boot/Refresh probes /v1/health and
captures the plugin's capability list. MCP handlers (PR-5) ask
SupportsCapability before exposing capability-gated features —
e.g., agents can only request semantic search when "embedding"
is reported.
2. Circuit breaker. Three consecutive failures open the breaker for
60 seconds; while open, calls fail fast with ErrBreakerOpen.
Picked these constants because:
- 3 failures: long enough to skip transient blips, short enough
to react before all in-flight handlers stack on the timeout
- 60s cooldown: long enough to back off a flapping plugin,
short enough that recovery is felt within a single session
4xx responses do NOT count toward the breaker (those are client
bugs, not plugin health issues); 5xx + transport errors do.
What ships:
- workspace-server/internal/memory/client/client.go
- client_test.go: 100% statement coverage
Coverage corner cases pinned:
- env-var success branches in New (parseDurationEnv applied)
- json.Marshal error (via channel in Propagation)
- http.NewRequestWithContext error (via unbalanced bracket in BaseURL)
- 204 NoContent on endpoint that normally has a body
- 4xx vs 5xx breaker behavior (4xx must NOT trip)
- breaker cooldown elapsed → reset on next success
- all 6 public endpoints fail-fast when breaker is open
This package has no callers in this PR; integration starts in PR-5.
c1cff3169f