Fix declaration emit readonly tuple regression from as const satisfies

[Copilot]

• Understand the issue: regression in declaration emit where readonly is incorrectly added to tuple types after PR Port --isolatedDeclarations related node builder logic, with baseline updates #2459
• Create test case from issue comment #4105762522
• Run test and accept baselines to show the declaration emit issue
• Identify root cause: pseudoTypeEquivalentToType doesn't check the tuple readonly flag, and pseudoTypeToNode always emits tuples as readonly
• Apply fix to pseudoTypeEquivalentToType in pseudotypenodebuilder.go
• Run test and verify fix produces correct output matching TypeScript 5.9/6.0
• Accept corrected baselines
• Run full test suite - all tests pass

Original prompt

---

This section details on the original issue you should resolve

<issue_title>0320 vs 0321</issue_title>
<issue_description>## Steps to reproduce

clone, do a bun i and then bun run build
see https://github.com/workglow-dev/workglow/actions/runs/23388170259/job/68038462188

tsc and tsgo as of yesterday had no issues. This only started today with Saturday March 21 build. tsgo =7.0.0-dev.20260321.1

when pinned to 7.0.0-dev.20260320.1

https://github.com/workglow-dev/workglow/actions/runs/23388410799/job/68039071095 (no issues)</issue_description>

<agent_instructions>See #3192 (comment) for the test. Make the test first, run and accept baselines to show the declaration emit issue, then work on the bug. See all referenced issues and PRs.</agent_instructions>

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

@jakebailey A CI log isn't a repro; can you give us something we can test in isolation without a big repo? Or bisect it? @jakebailey Yes, if it differs from TS6, it should be reported; I am assuming a regression from #2459

Custom agent used: Issue Investigator
An expert at reproducing, investigating, and diagnosing issues

• Fixes 0320 vs 0321 #3192

---

⌨️ Start Copilot coding agent tasks without leaving your editor — available in VS Code, Visual Studio, JetBrains IDEs and Eclipse.

[jakebailey]

@copilot delete this

[Copilot]

Done in c45b733.