diff --git a/plugins/github/README.md b/plugins/github/README.md
index aafa973242..c5d7a00219 100644
--- a/plugins/github/README.md
+++ b/plugins/github/README.md
@@ -34,7 +34,10 @@ it reports needs-configuration. No tokens are stored by the plugin.
 
 - Every BB project source whose checkout has a GitHub `origin` remote
   (repo → project mapping is also how spawn picks the project).
-- Plus the `extraRepos` setting: comma-separated `owner/repo` list.
+- Plus the `extraRepos` setting: comma-separated `owner/repo` list. Entries that
+  are not `owner/repo` — a `owner/*` wildcard, a bare owner, a typo — are not
+  tracked; `bb github repos` names them on stderr and the plugin log warns once
+  per distinct set. Wildcards are not supported.
 - `defaultProject` setting: where threads spawn for repos with no project.
 
 ```
diff --git a/plugins/github/server.rpc.test.ts b/plugins/github/server.rpc.test.ts
index 9bf668fb76..bdacac5589 100644
--- a/plugins/github/server.rpc.test.ts
+++ b/plugins/github/server.rpc.test.ts
@@ -195,16 +195,61 @@ afterEach(() => {
   rmSync(binDir, { recursive: true, force: true });
 });
 
-async function loadPlugin() {
+async function loadPlugin(extraRepos = "acme/widgets") {
   const host = createFakePluginHost({
     pluginId: "github",
-    settings: { extraRepos: "acme/widgets" },
+    settings: { extraRepos },
   });
   await plugin(host.bb);
   return host;
 }
 
 describe("github plugin RPC behavior", () => {
+  // A stored-but-unusable extraRepos entry used to look exactly like one that
+  // matched nothing: no log line, and `bb github repos` listed the usable names
+  // without mentioning what it had dropped.
+  it("reports extraRepos entries it cannot honor instead of dropping them", async () => {
+    const { harness } = await loadPlugin("acme/widgets, ACME-ORG/*, nonsense");
+
+    await expect(harness.runCli(["repos"])).resolves.toEqual({
+      exitCode: 0,
+      stdout: "acme/widgets",
+      stderr:
+        'ignoring 2 extraRepos entries that are not "owner/repo": ACME-ORG/*, nonsense\n',
+    });
+    expect(harness.logEntries).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          level: "warn",
+          message: 'ignoring 2 extraRepos entries that are not "owner/repo": ACME-ORG/*, nonsense',
+        }),
+      ]),
+    );
+
+    // The warning is emitted per distinct set, not per discovery: `repos`
+    // forces a fresh read every time and a background sync lapses the cache on
+    // its own, so warning per pass would repeat this line forever.
+    await harness.runCli(["repos"]);
+    expect(
+      harness.logEntries.filter(
+        (entry) => entry.level === "warn" && entry.message.includes("extraRepos"),
+      ),
+    ).toHaveLength(1);
+  });
+
+  it("says nothing about extraRepos when every entry is usable", async () => {
+    const { harness } = await loadPlugin("acme/widgets");
+
+    await expect(harness.runCli(["repos"])).resolves.toEqual({
+      exitCode: 0,
+      stdout: "acme/widgets",
+      stderr: "",
+    });
+    expect(
+      harness.logEntries.filter((entry) => entry.message.includes("extraRepos")),
+    ).toEqual([]);
+  });
+
   it("syncs, filters, mutates, and exposes the same cached issue across surfaces", async () => {
     const { harness } = await loadPlugin();
 
diff --git a/plugins/github/server.test.ts b/plugins/github/server.test.ts
index cbe21f132e..fd412da5bc 100644
--- a/plugins/github/server.test.ts
+++ b/plugins/github/server.test.ts
@@ -5,6 +5,7 @@ import { createFakePluginHost } from "@get-bb/plugin-sdk/testing";
 import {
   fetchRepoItems,
   githubRpcContract,
+  parseExtraRepos,
   parsePaginatedGhApi,
   validateGithubCliArgs,
 } from "./server";
@@ -128,6 +129,30 @@ describe("GitHub RPC contract", () => {
     );
   });
 
+  it("separates usable extraRepos entries from ones it cannot honor", () => {
+    expect(parseExtraRepos("get-bb/bb, nonsense")).toEqual({
+      repos: ["get-bb/bb"],
+      ignored: ["nonsense"],
+    });
+    // The wildcard from the report: stored, never matched, previously silent.
+    expect(parseExtraRepos("SOME-ORG/*")).toEqual({
+      repos: [],
+      ignored: ["SOME-ORG/*"],
+    });
+    // Separators and blanks are structure, not entries — an empty setting has
+    // nothing to complain about.
+    expect(parseExtraRepos("")).toEqual({ repos: [], ignored: [] });
+    expect(parseExtraRepos("  ,, \n ")).toEqual({ repos: [], ignored: [] });
+    expect(parseExtraRepos(" acme/one\nacme/two , acme/one ")).toEqual({
+      repos: ["acme/one", "acme/two"],
+      ignored: [],
+    });
+    expect(parseExtraRepos("bad/repo/shape acme").ignored).toEqual([
+      "bad/repo/shape",
+      "acme",
+    ]);
+  });
+
   it("rejects CLI arguments that would otherwise broaden a repository query", () => {
     expect(validateGithubCliArgs(["issues", "get-bb/bb"])).toBeNull();
     expect(validateGithubCliArgs(["issues", "bad/repo/shape"])).toContain(
diff --git a/plugins/github/server.ts b/plugins/github/server.ts
index 4b26ba1563..4a08c20af6 100644
--- a/plugins/github/server.ts
+++ b/plugins/github/server.ts
@@ -345,6 +345,36 @@ function isRepoName(value: unknown): value is string {
   return typeof value === "string" && /^[\w.-]+\/[\w.-]+$/.test(value);
 }
 
+/**
+ * Split the `extraRepos` setting into the names we track and the entries we
+ * cannot. Anything that is not `owner/repo` — a `SOME-ORG/*` wildcard, a typo,
+ * a bare owner — is reported rather than dropped, so a setting that was stored
+ * but not honored is distinguishable from one that matched nothing.
+ */
+export function parseExtraRepos(raw: string): {
+  repos: string[];
+  ignored: string[];
+} {
+  const repos: string[] = [];
+  const ignored: string[] = [];
+  for (const entry of raw.split(/[\s,]+/)) {
+    if (entry === "") continue;
+    if (isRepoName(entry)) {
+      if (!repos.includes(entry)) repos.push(entry);
+    } else if (!ignored.includes(entry)) {
+      ignored.push(entry);
+    }
+  }
+  return { repos, ignored };
+}
+
+function describeIgnoredExtraRepos(ignored: string[]): string {
+  return (
+    `ignoring ${ignored.length} extraRepos ${ignored.length === 1 ? "entry" : "entries"} ` +
+    `that ${ignored.length === 1 ? "is" : "are"} not "owner/repo": ${ignored.join(", ")}`
+  );
+}
+
 function run(
   file: string,
   args: string[],
@@ -578,6 +608,11 @@ export default async function plugin(bb: BbPluginApi) {
   // ------------------------------------------------------------------
   let repoCache: { repos: RepoInfo[]; fetchedAt: number } | null = null;
 
+  // The extraRepos entries the last discovery could not use, kept so `bb github
+  // repos` can say so on the surface the reporter looked at.
+  let ignoredExtraRepos: string[] = [];
+  let lastIgnoredExtraReposKey: string | null = null;
+
   async function discoverRepos(force = false): Promise<RepoInfo[]> {
     if (!force && repoCache !== null && Date.now() - repoCache.fetchedAt < 60_000) {
       return repoCache.repos;
@@ -609,11 +644,23 @@ export default async function plugin(bb: BbPluginApi) {
       );
     }
     const { extraRepos } = await settings.get();
-    for (const raw of extraRepos.split(/[\s,]+/)) {
-      if (isRepoName(raw) && !byRepo.has(raw)) {
+    const parsed = parseExtraRepos(extraRepos);
+    for (const raw of parsed.repos) {
+      if (!byRepo.has(raw)) {
         byRepo.set(raw, { repo: raw, projectId: null });
       }
     }
+    // Warn on the set rather than on every discovery: discoverRepos re-reads
+    // settings whenever the 60s cache lapses, and a background sync would
+    // otherwise repeat the same line forever.
+    const ignoredKey = parsed.ignored.join(",");
+    if (ignoredKey !== lastIgnoredExtraReposKey) {
+      lastIgnoredExtraReposKey = ignoredKey;
+      if (parsed.ignored.length > 0) {
+        bb.log.warn(describeIgnoredExtraRepos(parsed.ignored));
+      }
+    }
+    ignoredExtraRepos = parsed.ignored;
     const repos = [...byRepo.values()];
     repoCache = { repos, fetchedAt: Date.now() };
     return repos;
@@ -1567,14 +1614,23 @@ export default async function plugin(bb: BbPluginApi) {
         }
         if (sub === "repos") {
           const repos = await discoverRepos(true);
+          const warning =
+            ignoredExtraRepos.length > 0
+              ? { stderr: `${describeIgnoredExtraRepos(ignoredExtraRepos)}\n` }
+              : {};
           if (repos.length === 0) {
-            return { exitCode: 0, stdout: "No tracked repos. Attach a project with a GitHub remote or set extraRepos." };
+            return {
+              exitCode: 0,
+              stdout: "No tracked repos. Attach a project with a GitHub remote or set extraRepos.",
+              ...warning,
+            };
           }
           return {
             exitCode: 0,
             stdout: repos
               .map((entry) => `${entry.repo}${entry.projectId !== null ? `\t(${entry.projectId})` : ""}`)
               .join("\n"),
+            ...warning,
           };
         }
         if (sub === "issues" || sub === "prs") {