diff --git a/scripts/lib/extension-test-plan.mjs b/scripts/lib/extension-test-plan.mjs
index 14315f4cf71..3fb285fe3eb 100644
--- a/scripts/lib/extension-test-plan.mjs
+++ b/scripts/lib/extension-test-plan.mjs
@@ -31,26 +31,31 @@ const repoRoot = path.resolve(import.meta.dirname, "..", "..");
 export const DEFAULT_EXTENSION_TEST_SHARD_COUNT = 6;
 const EXTENSION_TEST_COST_MULTIPLIERS = {
   // CI shard planning uses measured wall time rather than raw file count.
-  // Import-heavy channel suites vary widely: Slack/Mattermost are much more
-  // expensive per file than Matrix/Discord/MSTeams.
+  // These ratios come from Blacksmith extension batch timings; import-heavy
+  // suites vary widely, and file count alone leaves long tail shards.
+  "test/vitest/vitest.extension-acpx.config.ts": 0.75,
   "test/vitest/vitest.extension-bluebubbles.config.ts": 0.8,
-  "test/vitest/vitest.extension-browser.config.ts": 0.55,
-  "test/vitest/vitest.extension-discord.config.ts": 0.55,
-  "test/vitest/vitest.extension-feishu.config.ts": 1.1,
-  "test/vitest/vitest.extension-imessage.config.ts": 0.9,
-  "test/vitest/vitest.extension-matrix.config.ts": 0.25,
-  "test/vitest/vitest.extension-mattermost.config.ts": 1.05,
+  "test/vitest/vitest.extension-browser.config.ts": 0.3,
+  "test/vitest/vitest.extension-diffs.config.ts": 0.6,
+  "test/vitest/vitest.extension-discord.config.ts": 0.18,
+  "test/vitest/vitest.extension-feishu.config.ts": 0.18,
+  "test/vitest/vitest.extension-imessage.config.ts": 1.7,
+  "test/vitest/vitest.extension-irc.config.ts": 1.0,
+  "test/vitest/vitest.extension-line.config.ts": 1.1,
+  "test/vitest/vitest.extension-matrix.config.ts": 0.28,
+  "test/vitest/vitest.extension-mattermost.config.ts": 0.75,
   "test/vitest/vitest.extension-media.config.ts": 0.7,
-  "test/vitest/vitest.extension-memory.config.ts": 0.3,
+  "test/vitest/vitest.extension-memory.config.ts": 0.25,
   "test/vitest/vitest.extension-messaging.config.ts": 0.4,
   "test/vitest/vitest.extension-misc.config.ts": 0.7,
-  "test/vitest/vitest.extension-msteams.config.ts": 0.3,
+  "test/vitest/vitest.extension-msteams.config.ts": 0.4,
+  "test/vitest/vitest.extension-provider-openai.config.ts": 1.35,
   "test/vitest/vitest.extension-providers.config.ts": 0.5,
-  "test/vitest/vitest.extension-qa.config.ts": 0.4,
-  "test/vitest/vitest.extension-slack.config.ts": 0.7,
-  "test/vitest/vitest.extension-telegram.config.ts": 0.4,
-  "test/vitest/vitest.extension-voice-call.config.ts": 0.25,
-  "test/vitest/vitest.extension-whatsapp.config.ts": 0.6,
+  "test/vitest/vitest.extension-qa.config.ts": 0.6,
+  "test/vitest/vitest.extension-slack.config.ts": 0.14,
+  "test/vitest/vitest.extension-telegram.config.ts": 0.15,
+  "test/vitest/vitest.extension-voice-call.config.ts": 0.27,
+  "test/vitest/vitest.extension-whatsapp.config.ts": 0.5,
   "test/vitest/vitest.extension-zalo.config.ts": 0.7,
   // This shared config is comparatively cheap per file, so raw file count
   // overstates its real wall-clock cost during CI shard planning.
diff --git a/test/scripts/test-extension.test.ts b/test/scripts/test-extension.test.ts
index 6ed409aee7f..c91f9036f63 100644
--- a/test/scripts/test-extension.test.ts
+++ b/test/scripts/test-extension.test.ts
@@ -474,24 +474,24 @@ describe("scripts/test-extension.mjs", () => {
     const totals = shards.map((shard) => shard.estimatedCost);
     expect(Math.max(...totals) - Math.min(...totals)).toBeLessThanOrEqual(1);
 
-    const msTeamsShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("msteams"));
-    const feishuShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("feishu"));
     const browserShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("browser"));
-    const slackShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("slack"));
-    const matrixShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("matrix"));
+    const imessageShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("imessage"));
     const mattermostShardIndex = shards.findIndex((shard) =>
       shard.extensionIds.includes("mattermost"),
     );
+    const openAiShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("openai"));
+    const qaLabShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("qa-lab"));
+    const whatsappShardIndex = shards.findIndex((shard) => shard.extensionIds.includes("whatsapp"));
 
-    expect(msTeamsShardIndex).toBeGreaterThanOrEqual(0);
-    expect(feishuShardIndex).toBeGreaterThanOrEqual(0);
-    expect(msTeamsShardIndex).not.toBe(feishuShardIndex);
     expect(browserShardIndex).toBeGreaterThanOrEqual(0);
-    expect(slackShardIndex).toBeGreaterThanOrEqual(0);
-    expect(browserShardIndex).not.toBe(slackShardIndex);
-    expect(matrixShardIndex).toBeGreaterThanOrEqual(0);
+    expect(imessageShardIndex).toBeGreaterThanOrEqual(0);
     expect(mattermostShardIndex).toBeGreaterThanOrEqual(0);
-    expect(matrixShardIndex).not.toBe(mattermostShardIndex);
+    expect(openAiShardIndex).toBeGreaterThanOrEqual(0);
+    expect(qaLabShardIndex).toBeGreaterThanOrEqual(0);
+    expect(whatsappShardIndex).toBeGreaterThanOrEqual(0);
+    expect(browserShardIndex).not.toBe(qaLabShardIndex);
+    expect(imessageShardIndex).not.toBe(openAiShardIndex);
+    expect(mattermostShardIndex).not.toBe(whatsappShardIndex);
   });
 
   it("runs extension batch config groups concurrently when requested", async () => {