Fix declaration emit for symbol property keys from external modules

[Copilot]

• Understand the issue: Declaration emit uses symbol property keys without importing them
• Create test case to reproduce the issue
• Identify root cause: UniqueESSymbol property keys from external modules weren't being validated for value accessibility
• Implement fix: Add accessibility check in getPropertyNameNodeForSymbolFromNameType and addPropertyToElementList
• Update test baseline to reflect the fix (now generates TS4118 error instead of broken d.ts)
• Verify existing tests still pass (uniqueSymbolPropertyDeclarationEmit)
• Run linting and formatting
• Run full test suite to check for regressions
• Request code review

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Declaration file emits symbol property keys without importing them</issue_title>
<issue_description>### 🔎 Search Terms

missing import in d.ts, symbol key not imported, unique symbol dts emit, dataTagSymbol not found, declaration file missing import

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about "Behavior That Looks Wrong (And Arguably Is) But Is Currently Working As Intended"
• This bug is reproducible in the latest stable (5.9.2), and still occurs in next (6.0.0-dev.20250811)

⏯ Playground Link

https://stackblitz.com/edit/stackblitz-starters-vflvduch?file=src%2Findex.ts

💻 Code

Here's the code from the Stackblitz reproduction above.

src/index.ts:

import { fn } from 'test-pkg';
export const value = fn();

node_modules/test-pkg/index.d.ts:

declare const lostSymbol: unique symbol;
type lostSymbol = typeof lostSymbol;

type SomeGeneric<T> = {
    [lostSymbol]: T;
};

declare function fn(): SomeGeneric<unknown>;

export {
    lostSymbol,
    fn
};

🙁 Actual behavior

dist/index.d.ts:

export declare const value: {
    [lostSymbol]: unknown; // lostSymbol is not defined here and errors on the consumer's type check
};

🙂 Expected behavior

dist/index.d.ts:

import { lostSymbol } from 'test-pkg'; // should import from pacakge

export declare const value: {
    [lostSymbol]: unknown;
};

Additional information about the issue

Related?: #49065</issue_description>

Comments on the Issue (you are @copilot in this section)

@RyanCavanaugh I don't know why the bot did that 🤔

• Fixes Declaration file emits symbol property keys without importing them #62257

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[DanielRosenwasser]

@copilot keep at it