From 34afe10b002bdf0e2b90be442ccd42be232b9d95 Mon Sep 17 00:00:00 2001
From: Vincent Koc <vincentkoc@ieee.org>
Date: Tue, 14 Apr 2026 17:08:13 +0100
Subject: [PATCH] perf(config): skip duplicate channel legacy rule loads

---
 src/channels/plugins/legacy-config.test.ts | 31 ++++++++++++++++++++++
 src/channels/plugins/legacy-config.ts      | 17 +++++++++---
 src/config/legacy.ts                       | 17 +++++++++++-
 3 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/src/channels/plugins/legacy-config.test.ts b/src/channels/plugins/legacy-config.test.ts
index fb65f43f30c..63024fca5d4 100644
--- a/src/channels/plugins/legacy-config.test.ts
+++ b/src/channels/plugins/legacy-config.test.ts
@@ -136,4 +136,35 @@ describe("collectChannelLegacyConfigRules", () => {
     expect(loadBundledChannelDoctorContractApiMock).toHaveBeenCalledTimes(1);
     expect(loadBundledChannelDoctorContractApiMock).toHaveBeenCalledWith("discord");
   });
+
+  it("skips channel ids already covered by explicit legacy rules", () => {
+    loadBundledChannelDoctorContractApiMock.mockImplementation((channelId: string) => ({
+      legacyConfigRules: [
+        {
+          path: ["channels", channelId],
+          message: `legacy ${channelId} rule`,
+        },
+      ],
+    }));
+
+    const rules = collectChannelLegacyConfigRules(
+      {
+        channels: {
+          discord: {},
+          telegram: {},
+        },
+      },
+      undefined,
+      new Set(["telegram"]),
+    );
+
+    expect(rules).toEqual([
+      {
+        path: ["channels", "discord"],
+        message: "legacy discord rule",
+      },
+    ]);
+    expect(loadBundledChannelDoctorContractApiMock).toHaveBeenCalledTimes(1);
+    expect(loadBundledChannelDoctorContractApiMock).toHaveBeenCalledWith("discord");
+  });
 });
diff --git a/src/channels/plugins/legacy-config.ts b/src/channels/plugins/legacy-config.ts
index 884c6c6fb84..3ac6c966590 100644
--- a/src/channels/plugins/legacy-config.ts
+++ b/src/channels/plugins/legacy-config.ts
@@ -38,10 +38,14 @@ function shouldIncludeLegacyRuleForTouchedPaths(
 function collectRelevantChannelIdsForTouchedPaths(params: {
   raw?: unknown;
   touchedPaths?: ReadonlyArray<ReadonlyArray<string>>;
+  excludedChannelIds?: ReadonlySet<ChannelId>;
 }): ChannelId[] {
   const channelIds = collectConfiguredChannelIds(params.raw);
+  const filteredChannelIds = params.excludedChannelIds?.size
+    ? channelIds.filter((channelId) => !params.excludedChannelIds?.has(channelId))
+    : channelIds;
   if (!params.touchedPaths || params.touchedPaths.length === 0) {
-    return channelIds;
+    return filteredChannelIds;
   }
 
   const touchedChannelIds = new Set<ChannelId>();
@@ -51,7 +55,7 @@ function collectRelevantChannelIdsForTouchedPaths(params: {
       continue;
     }
     if (!second) {
-      return channelIds;
+      return filteredChannelIds;
     }
     if (second === "defaults") {
       continue;
@@ -62,14 +66,19 @@ function collectRelevantChannelIdsForTouchedPaths(params: {
   if (touchedChannelIds.size === 0) {
     return [];
   }
-  return channelIds.filter((channelId) => touchedChannelIds.has(channelId));
+  return filteredChannelIds.filter((channelId) => touchedChannelIds.has(channelId));
 }
 
 export function collectChannelLegacyConfigRules(
   raw?: unknown,
   touchedPaths?: ReadonlyArray<ReadonlyArray<string>>,
+  excludedChannelIds?: ReadonlySet<ChannelId>,
 ): LegacyConfigRule[] {
-  const channelIds = collectRelevantChannelIdsForTouchedPaths({ raw, touchedPaths });
+  const channelIds = collectRelevantChannelIdsForTouchedPaths({
+    raw,
+    touchedPaths,
+    excludedChannelIds,
+  });
   const rules: LegacyConfigRule[] = [];
   const unresolvedChannelIds: ChannelId[] = [];
   for (const channelId of channelIds) {
diff --git a/src/config/legacy.ts b/src/config/legacy.ts
index 79bac2bd033..1fb703432d5 100644
--- a/src/config/legacy.ts
+++ b/src/config/legacy.ts
@@ -14,6 +14,20 @@ function getPathValue(root: Record<string, unknown>, path: string[]): unknown {
   return cursor;
 }
 
+function collectExplicitRuleOwnedChannelIds(
+  extraRules: readonly LegacyConfigRule[],
+): ReadonlySet<string> | undefined {
+  const channelIds = new Set<string>();
+  for (const rule of extraRules) {
+    const [first, second] = rule.path;
+    if (first !== "channels" || typeof second !== "string" || second === "defaults") {
+      continue;
+    }
+    channelIds.add(second);
+  }
+  return channelIds.size > 0 ? channelIds : undefined;
+}
+
 export function findLegacyConfigIssues(
   raw: unknown,
   sourceRaw?: unknown,
@@ -27,9 +41,10 @@ export function findLegacyConfigIssues(
   const sourceRoot =
     sourceRaw && typeof sourceRaw === "object" ? (sourceRaw as Record<string, unknown>) : root;
   const issues: LegacyConfigIssue[] = [];
+  const explicitRuleOwnedChannelIds = collectExplicitRuleOwnedChannelIds(extraRules);
   for (const rule of [
     ...LEGACY_CONFIG_RULES,
-    ...collectChannelLegacyConfigRules(raw, touchedPaths),
+    ...collectChannelLegacyConfigRules(raw, touchedPaths, explicitRuleOwnedChannelIds),
     ...extraRules,
   ]) {
     const cursor = getPathValue(root, rule.path);