diff --git a/scripts/print-scopes.ts b/scripts/print-scopes.ts
new file mode 100644
index 0000000..4d7377c
--- /dev/null
+++ b/scripts/print-scopes.ts
@@ -0,0 +1,19 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Prints the OAuth scopes that should be registered on the GCP consent
+ * screen, one per line. Sourced from FEATURE_GROUPS so the registration
+ * list and the runtime request list cannot drift.
+ *
+ * Used by scripts/setup-gcp.sh.
+ */
+
+import { getAllPossibleScopes } from '../workspace-server/src/features/feature-config';
+
+for (const scope of getAllPossibleScopes()) {
+  console.log(scope);
+}
diff --git a/scripts/setup-gcp.sh b/scripts/setup-gcp.sh
index 639850e..059fafc 100755
--- a/scripts/setup-gcp.sh
+++ b/scripts/setup-gcp.sh
@@ -91,19 +91,31 @@ echo -e "  4. Under ${GREEN}Test users${NC}, add the email addresses of anyone"
 echo -e "     who will use this extension (required while in Testing mode)"
 echo ""
 
-SCOPES=(
-    "https://www.googleapis.com/auth/documents"
-    "https://www.googleapis.com/auth/drive"
-    "https://www.googleapis.com/auth/calendar"
-    "https://www.googleapis.com/auth/chat.spaces"
-    "https://www.googleapis.com/auth/chat.messages"
-    "https://www.googleapis.com/auth/chat.memberships"
-    "https://www.googleapis.com/auth/userinfo.profile"
-    "https://www.googleapis.com/auth/gmail.modify"
-    "https://www.googleapis.com/auth/directory.readonly"
-    "https://www.googleapis.com/auth/presentations.readonly"
-    "https://www.googleapis.com/auth/spreadsheets.readonly"
-)
+# Single source of truth: scopes are computed from FEATURE_GROUPS in
+# workspace-server/src/features/feature-config.ts. See issue #323.
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+SCOPES_OUTPUT=$(cd "$REPO_ROOT" && npx --no-install ts-node --transpile-only scripts/print-scopes.ts 2>&1)
+if [ $? -ne 0 ]; then
+    echo -e "${RED}Error: Failed to compute OAuth scopes from feature-config.ts.${NC}"
+    echo -e "${RED}Did you run 'npm install' at the repo root?${NC}"
+    echo "$SCOPES_OUTPUT"
+    exit 1
+fi
+
+SCOPES=()
+# Filter to https:// lines so any Node/ts-node warnings written to stderr
+# (captured via 2>&1 above so we can surface them on failure) don't end up
+# in the user-visible scope list.
+while IFS= read -r line; do
+    [[ "$line" == https://* ]] && SCOPES+=("$line")
+done <<< "$SCOPES_OUTPUT"
+
+if [ ${#SCOPES[@]} -eq 0 ]; then
+    echo -e "${RED}Error: print-scopes.ts produced no scope output.${NC}"
+    echo "$SCOPES_OUTPUT"
+    exit 1
+fi
 
 for scope in "${SCOPES[@]}"; do
     echo -e "     ${GREEN}$scope${NC}"
diff --git a/workspace-server/src/__tests__/features/feature-config.test.ts b/workspace-server/src/__tests__/features/feature-config.test.ts
index f304664..ce83667 100644
--- a/workspace-server/src/__tests__/features/feature-config.test.ts
+++ b/workspace-server/src/__tests__/features/feature-config.test.ts
@@ -4,8 +4,16 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import { execSync } from 'node:child_process';
+import { readFileSync } from 'node:fs';
+import { join } from 'node:path';
+
 import { describe, it, expect } from '@jest/globals';
-import { FEATURE_GROUPS, featureGroupKey } from '../../features/feature-config';
+import {
+  FEATURE_GROUPS,
+  featureGroupKey,
+  getAllPossibleScopes,
+} from '../../features/feature-config';
 
 describe('feature-config', () => {
   it('should have unique feature group keys', () => {
@@ -57,3 +65,64 @@ describe('feature-config', () => {
     expect(timeRead!.scopes).toEqual([]);
   });
 });
+
+describe('getAllPossibleScopes (issue #323)', () => {
+  it('should include both write and readonly scopes for paired groups', () => {
+    const scopes = getAllPossibleScopes();
+    // Both must be registered on the consent screen — users may flip
+    // <service>.write off, which causes <service>.readonly to be requested.
+    expect(scopes).toContain('https://www.googleapis.com/auth/drive');
+    expect(scopes).toContain('https://www.googleapis.com/auth/drive.readonly');
+    expect(scopes).toContain('https://www.googleapis.com/auth/gmail.modify');
+    expect(scopes).toContain('https://www.googleapis.com/auth/gmail.readonly');
+    expect(scopes).toContain('https://www.googleapis.com/auth/calendar');
+    expect(scopes).toContain(
+      'https://www.googleapis.com/auth/calendar.readonly',
+    );
+  });
+
+  it('should exclude default-OFF group scopes that are not in any default-ON group', () => {
+    const scopes = getAllPossibleScopes();
+    // tasks.* are default-OFF and their scopes are not shared with any
+    // default-ON group, so they shouldn't be in the registration list.
+    expect(scopes).not.toContain('https://www.googleapis.com/auth/tasks');
+    expect(scopes).not.toContain(
+      'https://www.googleapis.com/auth/tasks.readonly',
+    );
+  });
+
+  it('should be sorted and deduplicated', () => {
+    const scopes = getAllPossibleScopes();
+    const sortedUnique = [...new Set(scopes)].sort();
+    expect(scopes).toEqual(sortedUnique);
+  });
+
+  it('print-scopes.ts should emit the same list (drift guard for setup-gcp.sh)', () => {
+    // setup-gcp.sh shells out to scripts/print-scopes.ts; if this test
+    // fails, the consent screen registration list will drift from
+    // FEATURE_GROUPS — which is the bug in issue #323.
+    const repoRoot = join(__dirname, '..', '..', '..', '..');
+    // execSync (not execFileSync) so Windows can resolve npx.cmd via the
+    // shell. Tests run on ubuntu/macos/windows.
+    const output = execSync(
+      'npx --no-install ts-node --transpile-only scripts/print-scopes.ts',
+      { cwd: repoRoot, encoding: 'utf8' },
+    );
+    const printed = output.trim().split(/\r?\n/);
+    expect(printed).toEqual(getAllPossibleScopes());
+  });
+
+  it('setup-gcp.sh should not contain a hardcoded SCOPES list (drift guard)', () => {
+    // If someone re-inlines the list, this test catches it.
+    const repoRoot = join(__dirname, '..', '..', '..', '..');
+    const setupScript = readFileSync(
+      join(repoRoot, 'scripts', 'setup-gcp.sh'),
+      'utf8',
+    );
+    // A hardcoded list would have a literal scope URL inside SCOPES=( ... ).
+    const hardcodedMatch = setupScript.match(
+      /SCOPES=\(\s*"https:\/\/www\.googleapis\.com\//,
+    );
+    expect(hardcodedMatch).toBeNull();
+  });
+});
diff --git a/workspace-server/src/__tests__/features/feature-resolver.test.ts b/workspace-server/src/__tests__/features/feature-resolver.test.ts
index c8390c4..fa473f3 100644
--- a/workspace-server/src/__tests__/features/feature-resolver.test.ts
+++ b/workspace-server/src/__tests__/features/feature-resolver.test.ts
@@ -196,4 +196,58 @@ describe('resolveFeatures', () => {
     const unique = new Set(requiredScopes);
     expect(requiredScopes.length).toBe(unique.size);
   });
+
+  describe('read/write scope dedup (issue #323)', () => {
+    const READONLY_PAIRS: Array<[string, string]> = [
+      ['drive.readonly', 'drive'],
+      ['calendar.readonly', 'calendar'],
+      ['chat.spaces.readonly', 'chat.spaces'],
+      ['chat.messages.readonly', 'chat.messages'],
+      ['chat.memberships.readonly', 'chat.memberships'],
+      ['gmail.readonly', 'gmail.modify'],
+    ];
+    const fullUrl = (s: string) => `https://www.googleapis.com/auth/${s}`;
+
+    it.each(READONLY_PAIRS)(
+      'should not request %s when paired write scope is enabled (defaults)',
+      (readonlyScope, writeScope) => {
+        const { requiredScopes } = resolveFeatures();
+        expect(requiredScopes).not.toContain(fullUrl(readonlyScope));
+        expect(requiredScopes).toContain(fullUrl(writeScope));
+      },
+    );
+
+    it.each([
+      ['drive.write:off', 'drive.readonly'],
+      ['calendar.write:off', 'calendar.readonly'],
+      ['gmail.write:off', 'gmail.readonly'],
+      ['chat.write:off', 'chat.spaces.readonly'],
+    ])(
+      'should request readonly scope when write group disabled (%s)',
+      (override, readonlyScope) => {
+        const { requiredScopes } = resolveFeatures(undefined, override);
+        expect(requiredScopes).toContain(fullUrl(readonlyScope));
+      },
+    );
+
+    it('should not affect tool registration — read tools stay enabled when write is on', () => {
+      const { enabledTools } = resolveFeatures();
+      expect(enabledTools.has('drive.search')).toBe(true);
+      expect(enabledTools.has('gmail.search')).toBe(true);
+      expect(enabledTools.has('calendar.list')).toBe(true);
+      expect(enabledTools.has('chat.listSpaces')).toBe(true);
+    });
+
+    it('should still include read scopes for services without a write group (people)', () => {
+      const { requiredScopes } = resolveFeatures();
+      expect(requiredScopes).toContain(fullUrl('directory.readonly'));
+      expect(requiredScopes).toContain(fullUrl('userinfo.profile'));
+    });
+
+    it('should still include readonly scopes for default-OFF write groups (slides, sheets)', () => {
+      const { requiredScopes } = resolveFeatures();
+      expect(requiredScopes).toContain(fullUrl('presentations.readonly'));
+      expect(requiredScopes).toContain(fullUrl('spreadsheets.readonly'));
+    });
+  });
 });
diff --git a/workspace-server/src/features/feature-config.ts b/workspace-server/src/features/feature-config.ts
index e3a2cb1..5b4e810 100644
--- a/workspace-server/src/features/feature-config.ts
+++ b/workspace-server/src/features/feature-config.ts
@@ -255,3 +255,23 @@ export const FEATURE_GROUPS: readonly FeatureGroup[] = [
     defaultEnabled: false,
   },
 ] as const satisfies readonly FeatureGroup[];
+
+/**
+ * Every scope that any default-enabled feature group could request.
+ *
+ * This is the registration list for the OAuth consent screen — broader than
+ * the runtime request set, because users can disable individual write groups
+ * via WORKSPACE_FEATURE_OVERRIDES, which causes the paired read group's
+ * `.readonly` scope to be requested. Both must already be registered, or
+ * unverified apps hit "This app is blocked."
+ *
+ * Returned sorted for stable diffs in `setup-gcp.sh`.
+ */
+export function getAllPossibleScopes(): string[] {
+  const set = new Set<string>();
+  for (const fg of FEATURE_GROUPS) {
+    if (!fg.defaultEnabled) continue;
+    for (const scope of fg.scopes) set.add(scope);
+  }
+  return [...set].sort();
+}
diff --git a/workspace-server/src/features/feature-resolver.ts b/workspace-server/src/features/feature-resolver.ts
index 6551a91..ec9712d 100644
--- a/workspace-server/src/features/feature-resolver.ts
+++ b/workspace-server/src/features/feature-resolver.ts
@@ -145,7 +145,13 @@ export function resolveFeatures(
     }
   }
 
-  // Collect enabled tools and scopes
+  // Collect enabled tools and scopes.
+  //
+  // Scope dedup: when a service's `.write` group is enabled alongside its
+  // `.read` group, the write scope already grants read access at the API
+  // level, so we skip the read group's scopes. Avoids prompting the user
+  // for both `drive` and `drive.readonly` (and equivalents) on consent.
+  // Tools are unaffected — read tools still get registered.
   const enabledTools = new Set<string>();
   const scopeSet = new Set<string>();
 
@@ -153,9 +159,17 @@ export function resolveFeatures(
     const key = featureGroupKey(fg);
     if (!groupEnabled.get(key)) continue;
 
-    // Add scopes for this enabled group
-    for (const scope of fg.scopes) {
-      scopeSet.add(scope);
+    const writeKey = `${fg.service}.write`;
+    const subsumedByWrite =
+      fg.group === 'read' &&
+      writeKey !== key &&
+      groupIndex.has(writeKey) &&
+      groupEnabled.get(writeKey) === true;
+
+    if (!subsumedByWrite) {
+      for (const scope of fg.scopes) {
+        scopeSet.add(scope);
+      }
     }
 
     // Add tools (minus individually disabled ones)
diff --git a/workspace-server/src/features/index.ts b/workspace-server/src/features/index.ts
index c94cd04..ea418e5 100644
--- a/workspace-server/src/features/index.ts
+++ b/workspace-server/src/features/index.ts
@@ -4,7 +4,11 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-export { FEATURE_GROUPS, featureGroupKey } from './feature-config';
+export {
+  FEATURE_GROUPS,
+  featureGroupKey,
+  getAllPossibleScopes,
+} from './feature-config';
 export type { FeatureGroup } from './feature-config';
 export { resolveFeatures, parseOverrides } from './feature-resolver';
 export type { ResolvedFeatures } from './feature-resolver';