diff --git a/.agents/skills/freehire-search/SKILL.md b/.agents/skills/freehire-search/SKILL.md
index c748a6a9..c329216a 100644
--- a/.agents/skills/freehire-search/SKILL.md
+++ b/.agents/skills/freehire-search/SKILL.md
@@ -169,6 +169,11 @@ result carries at least `id` (the freehire slug), `title`, `company`, `location`
 omit the description — it would swamp a scannable list. All errors are written to
 **stderr** as `{ "error": "...", "code": "..." }` and the process exits with code `1`.
 
+One diagnostic is not an error: a `--region` (or `--facet regions=`) value outside the
+documented vocabulary - `us` is a country code, not a region - prints
+`{ "warning": "...", "code": "REGION_VALUE_UNKNOWN" }` on **stderr** after the results,
+and the process still exits `0` with stdout a valid JSON document.
+
 ## Partial data
 
 Facets are derived per-posting and can be **incomplete** — geography especially.
diff --git a/.agents/skills/freehire-search/cli/README.md b/.agents/skills/freehire-search/cli/README.md
index 63b8f8ce..4901d6f5 100644
--- a/.agents/skills/freehire-search/cli/README.md
+++ b/.agents/skills/freehire-search/cli/README.md
@@ -43,6 +43,9 @@ Compose (`make up` → API on `:8080`, same `/api/v1/...` paths).
 
 `search` accepts `--format json|table|plain` (default `json`); `detail` accepts `--format json|plain`.
 All errors are written to **stderr** as `{ "error": "...", "code": "..." }` with exit code `1`.
+One diagnostic is a warning instead: a `--region` value outside the documented vocabulary
+prints `{ "warning": "...", "code": "REGION_VALUE_UNKNOWN" }` to stderr after the results,
+and exits `0`, leaving stdout a valid JSON document.
 
 `search` hits the API's agent endpoint, so every JSON result already carries the
 posting's **full** description (Markdown by default, `--description-format
diff --git a/.agents/skills/freehire-search/cli/src/commands/search.ts b/.agents/skills/freehire-search/cli/src/commands/search.ts
index 49be3728..ac8a5e4a 100644
--- a/.agents/skills/freehire-search/cli/src/commands/search.ts
+++ b/.agents/skills/freehire-search/cli/src/commands/search.ts
@@ -110,6 +110,57 @@ function renderPlain(rows: JobResult[]): string {
   return rows.map(block).join("\n\n")
 }
 
+// freehire's contract - the openapi `Regions` enum and `RegionValues` in vocab.go -
+// defines a closed set: these nine buckets plus `none`. Anything else is a stray
+// tag, `us` above all, which is a country code that matches only a handful of
+// postings. A search filtered on one therefore looks empty or nearly empty, so the
+// CLI says the value is wrong instead of letting it read as a thin market.
+const REGION_VALUES = [
+  "global",
+  "north_america",
+  "latam",
+  "eu",
+  "uk",
+  "mena",
+  "africa",
+  "apac",
+  "cis",
+  "none",
+] as const
+
+/** Region values the caller filtered on: `--region` plus the `--facet regions=` escape hatch. */
+function requestedRegions(opts: SearchOpts): string[] {
+  return [...opts.regions, ...(opts.facets.regions ?? [])]
+}
+
+/**
+ * One line on stderr when a region filter uses a value outside the closed
+ * vocabulary, written after stdout and without touching the exit code, so a bad
+ * parameter never reads as "no postings". The result count is deliberately not
+ * consulted: a broad query returns real hits under a stray tag and is still wrong,
+ * which is exactly the case a zero-result check would miss.
+ */
+function warnOnUnknownRegion(opts: SearchOpts): void {
+  const requested = requestedRegions(opts)
+  if (requested.length === 0) return
+  const known = new Set<string>(REGION_VALUES)
+  const unknown = [...new Set(requested.map((value) => value.trim().toLowerCase()))].filter(
+    (value) => value !== "" && !known.has(value),
+  )
+  if (unknown.length === 0) return
+  const country = unknown.includes("us")
+    ? " A country belongs in --country, e.g. --country US."
+    : " A country belongs in --country."
+  process.stderr.write(
+    JSON.stringify({
+      warning:
+        `--region ${unknown.join(", ")} is not a region value: freehire's regions are ` +
+        `${REGION_VALUES.join(", ")}.${country}`,
+      code: "REGION_VALUE_UNKNOWN",
+    }) + "\n",
+  )
+}
+
 export async function runSearch(opts: SearchOpts): Promise<number> {
   try {
     const path = opts.includeDescription === false ? LEAN_SEARCH_PATH : SEARCH_PATH
@@ -146,6 +197,9 @@ export async function runSearch(opts: SearchOpts): Promise<number> {
         ) + "\n",
       )
     }
+    // After stdout: a diagnostic must never interleave with the JSON, and the exit
+    // code stays 0 because a wrong filter value is not a failure of the request.
+    warnOnUnknownRegion(opts)
     return 0
   } catch (e) {
     writeError(e instanceof Error ? e.message : String(e), "SEARCH_FAILED")
diff --git a/.agents/skills/freehire-search/cli/tests/region-value-warning.test.ts b/.agents/skills/freehire-search/cli/tests/region-value-warning.test.ts
new file mode 100644
index 00000000..e32ea89c
--- /dev/null
+++ b/.agents/skills/freehire-search/cli/tests/region-value-warning.test.ts
@@ -0,0 +1,179 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import { runSearch, type SearchOpts } from "../src/commands/search"
+
+// freehire's contract defines a closed region vocabulary (nine buckets plus `none`),
+// so a value outside it is a wrong parameter, not a thin market: `us` is a country
+// code that still matches a handful of stray-tagged postings. The warning therefore
+// fires on the value alone - no network, and not only when the result is empty,
+// which is the case a count-based check would miss.
+
+const originalFetch = globalThis.fetch
+const originalStdoutWrite = process.stdout.write
+const originalStderrWrite = process.stderr.write
+
+const DOCUMENTED = ["global", "north_america", "latam", "eu", "uk", "mena", "africa", "apac", "cis", "none"]
+
+function capture(stream: "stdout" | "stderr"): { read: () => string } {
+  let buf = ""
+  const write = ((chunk: string | Uint8Array) => {
+    buf += chunk.toString()
+    return true
+  }) as typeof process.stdout.write
+  if (stream === "stdout") process.stdout.write = write
+  else process.stderr.write = write
+  return { read: () => buf }
+}
+
+function job() {
+  return {
+    public_slug: "senior-fullstack-engineer-acme-1a2b3c4d",
+    source: "greenhouse",
+    external_id: "1",
+    url: "https://example.com/jobs/1",
+    title: "Senior Fullstack Engineer",
+    company: "Acme",
+    company_slug: "acme",
+    location: "Remote",
+    description: "body",
+    skills: ["typescript"],
+    work_mode: "remote",
+    regions: ["us"],
+    countries: [],
+    cities: [],
+    posted_at: "2026-10-17T00:00:00Z",
+    created_at: "2026-10-17T00:00:00Z",
+    enrichment: {},
+  }
+}
+
+/** Serve one canned search answer; returns the URLs the CLI asked for. */
+function stubSearch(total: number): { urls: string[] } {
+  const urls: string[] = []
+  globalThis.fetch = (async (input: string | URL | Request) => {
+    urls.push(typeof input === "string" ? input : input instanceof URL ? input.href : input.url)
+    const results = total > 0 ? [job()] : []
+    return Response.json({ data: results, meta: { total } })
+  }) as typeof fetch
+  return { urls }
+}
+
+function opts(over: Partial<SearchOpts> = {}): SearchOpts {
+  return {
+    jobage: 14,
+    page: 1,
+    limit: 25,
+    format: "json",
+    descriptionFormat: "markdown",
+    regions: [],
+    countries: [],
+    cities: [],
+    seniority: [],
+    category: [],
+    skills: [],
+    facets: {},
+    ...over,
+  }
+}
+
+afterEach(() => {
+  globalThis.fetch = originalFetch
+  process.stdout.write = originalStdoutWrite
+  process.stderr.write = originalStderrWrite
+})
+
+describe("--region outside the closed vocabulary", () => {
+  test("warns on stderr, keeps stdout parseable, exits 0", async () => {
+    stubSearch(0)
+    const stdout = capture("stdout")
+    const stderr = capture("stderr")
+    const code = await runSearch(opts({ query: "typescript", regions: ["us"] }))
+    expect(code).toBe(0)
+    expect(JSON.parse(stdout.read()).meta.total).toBe(0)
+    const line = stderr.read()
+    expect(line).toContain("REGION_VALUE_UNKNOWN")
+    expect(line).toContain("--country US")
+    // One line, as asked: a stderr consumer reads a line, not a paragraph.
+    expect(line.trimEnd().split("\n")).toHaveLength(1)
+  })
+
+  test("warns even when the query returns postings", async () => {
+    // The case a zero-result check misses: a broad query returns real hits under a
+    // stray tag and the parameter is still wrong.
+    stubSearch(3)
+    capture("stdout")
+    const stderr = capture("stderr")
+    const code = await runSearch(opts({ query: "software engineer", regions: ["us"] }))
+    expect(code).toBe(0)
+    expect(stderr.read()).toContain("REGION_VALUE_UNKNOWN")
+  })
+
+  test("covers the --facet regions= escape hatch", async () => {
+    stubSearch(0)
+    capture("stdout")
+    const stderr = capture("stderr")
+    await runSearch(opts({ facets: { regions: ["us"] } }))
+    expect(stderr.read()).toContain("REGION_VALUE_UNKNOWN")
+  })
+
+  test("compares case-insensitively", async () => {
+    stubSearch(0)
+    capture("stdout")
+    const upperUnknown = capture("stderr")
+    await runSearch(opts({ regions: ["US"] }))
+    expect(upperUnknown.read()).toContain("REGION_VALUE_UNKNOWN")
+
+    process.stderr.write = originalStderrWrite
+    const upperKnown = capture("stderr")
+    await runSearch(opts({ regions: ["EU"] }))
+    expect(upperKnown.read()).toBe("")
+  })
+
+  test("names only the values outside the vocabulary", async () => {
+    stubSearch(0)
+    capture("stdout")
+    const stderr = capture("stderr")
+    await runSearch(opts({ regions: ["eu", "us", "north_america"] }))
+    const warning = JSON.parse(stderr.read()).warning as string
+    expect(warning).toContain("--region us is not a region value")
+    expect(warning).not.toContain("--region eu")
+  })
+
+  test("stays silent for every documented value", async () => {
+    for (const value of DOCUMENTED) {
+      stubSearch(0)
+      capture("stdout")
+      const stderr = capture("stderr")
+      await runSearch(opts({ regions: [value] }))
+      expect(stderr.read()).toBe("")
+      process.stderr.write = originalStderrWrite
+    }
+  })
+
+  test("warns after a table, not only after JSON", async () => {
+    stubSearch(1)
+    const stdout = capture("stdout")
+    const stderr = capture("stderr")
+    await runSearch(opts({ format: "table", regions: ["us"] }))
+    expect(stdout.read()).toContain("Senior Fullstack Engineer")
+    expect(stderr.read()).toContain("REGION_VALUE_UNKNOWN")
+  })
+
+  test("does not blame none when another value is the invalid one", async () => {
+    stubSearch(0)
+    capture("stdout")
+    const stderr = capture("stderr")
+    await runSearch(opts({ regions: ["none", "us"] }))
+    const warning = JSON.parse(stderr.read()).warning as string
+    expect(warning).toContain("--region us is not a region value")
+    expect(warning).toContain("--country US")
+  })
+
+  test("no region filter means no warning and one request", async () => {
+    const stub = stubSearch(0)
+    capture("stdout")
+    const stderr = capture("stderr")
+    await runSearch(opts({ query: "typescript" }))
+    expect(stderr.read()).toBe("")
+    expect(stub.urls).toHaveLength(1)
+  })
+})
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c7df633..c21161f0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,15 @@ per-file diff commands.
   `north_america`, `latam`, `apac`, `mena`, `africa`, `cis`) plus `none`, note that `eu` excludes
   the UK, and point single-country searches at `--country`.
 
+- **`freehire-search search` warns when `--region` gets a value outside freehire's vocabulary**
+  (#651, fixes #616, `.agents/skills/freehire-search/cli/src/commands/search.ts`, `SKILL.md`,
+  `cli/README.md`) - an unknown region such as `us` or `europe` matches nothing, so the search read
+  as "no postings" rather than "wrong parameter". `search` now checks `--region` and
+  `--facet regions=` against the nine buckets plus `none`, case-insensitively, and prints one
+  `REGION_VALUE_UNKNOWN` warning on stderr that lists the buckets and points a country at
+  `--country`. Results, stdout and the exit code are unchanged, so a bucket freehire adds later
+  still works.
+
 ## [1.7.3] - 2026-10-19
 
 ### Added