diff --git a/docs/superpowers/specs/2026-05-03-hyperguild-cli-design.md b/docs/superpowers/specs/2026-05-03-hyperguild-cli-design.md
index 8eeca1d..ed04577 100644
--- a/docs/superpowers/specs/2026-05-03-hyperguild-cli-design.md
+++ b/docs/superpowers/specs/2026-05-03-hyperguild-cli-design.md
@@ -49,7 +49,7 @@ Three needs converge on a single small Go binary:
 - **`tier` subcommand reuses `internal/tier.Detect` verbatim.** Probe URLs (`https://api.anthropic.com` and the LiteLLM base URL) come from environment: `ANTHROPIC_PROBE_URL` (default the literal Anthropic URL) and `LITELLM_BASE_URL` (no default — error if `--mode-needs-llm` and unset). Rationale: matching the supervisor's existing wiring means the CLI cannot disagree with the supervisor about tier; a single source of truth.
 
 - **`brain` subcommand calls the HTTP REST API.** Two nested subcommands:
-  - `brain query <topic>` issues `GET /query?q=<topic>&limit=<N>` (default `--limit 5`), prints results in human-readable form by default and with `--json` for machine consumption.
+  - `brain query <topic>` issues `POST /query` with JSON body `{query, limit}` (default `--limit 5`), prints results in human-readable form by default and with `--json` for machine consumption.
   - `brain write <type> <slug>` reads stdin, posts `POST /write` with JSON body `{type, slug, content}`, prints the resulting path on success.
   Rationale: HTTP REST is simpler than MCP framing for a CLI. Per CLAUDE.md, the REST endpoints are documented as the official non-MCP interface.