feat(router-generator): add isolatedDeclarations config option by guru-irl · Pull Request #7289 · TanStack/router

guru-irl · 2026-04-29T12:44:46Z

Summary

When a project enables TypeScript's --isolatedDeclarations (or the equivalent oxc setting), the route tree generated by router-generator currently triggers TS9010:

error TS9010: Variable must have an explicit type annotation with --isolatedDeclarations.
  const PostsRoute = PostsRouteImport.update({...} as any)
                                                        ^

This happens because the type of PostsRoute must be inferred from the return type of .update() — which crosses a file boundary, violating the isolated-declarations constraint.

Solution

Add an isolatedDeclarations boolean option to tsr.config.json (defaults to false). When enabled, the generator emits explicit : any annotations on route constants:

// Before (fails with --isolatedDeclarations)
const PostsRoute = PostsRouteImport.update({...} as any)

// After (isolatedDeclarations: true)
const PostsRoute: any = PostsRouteImport.update({...} as any)

The option is opt-in to avoid any impact on existing users. It is a no-op when disableTypes: true.

Type safety tradeoff

Using : any on route constants means typeof PostsRoute === any, which does collapse the router's type tree (breaking useRouteContext, useParams inference etc.). This is an accepted tradeoff for projects that need isolatedDeclarations compliance — they already pay the same price for other as any patterns in the generated file.

A future improvement could use a more precise type (e.g. the specific Route class type), but that would require the generator to know the exact return type of .update(), which is not currently feasible.

Test plan

Added isolated-declarations generator test fixture (copied from single-level)
Snapshot asserts : any is emitted on route constants when option is enabled
All 234 existing generator tests pass unchanged (option defaults to false)
tsc proof: const X = import.update({} as any) + export interface I { '/': typeof X } → TS9010 without : any, clean with : any

Summary by CodeRabbit

Release Notes

New Features
- Added isolatedDeclarations configuration option to the router generator for enhanced type handling in route declarations.
Tests
- Added test coverage for the new isolatedDeclarations configuration.

When `isolatedDeclarations: true` is set in tsr.config.json, the generator emits explicit `: any` type annotations on route constants: const PostsRoute: any = PostsRouteImport.update({...} as any) Without this annotation, TypeScript and oxc raise TS9010 ("Variable must have an explicit type annotation with --isolatedDeclarations") because the return type of `.update()` must be inferred across files. The option defaults to `false` to preserve existing behaviour. It is a no-op when `disableTypes: true` (JS output). Adds an `isolated-declarations` test fixture (copied from `single-level`) with a snapshot that asserts the `: any` annotations are emitted.

coderabbitai · 2026-04-29T12:45:05Z

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📝 Walkthrough

Walkthrough

This pull request introduces a new optional configuration flag, isolatedDeclarations, to the router generator. When enabled in combination with type generation, the generator conditionally adds a : any type annotation to generated route constants. Test fixtures and snapshots are provided to validate the feature.

Changes

Cohort / File(s)	Summary
Configuration & Core Logic `packages/router-generator/src/config.ts`, `packages/router-generator/src/generator.ts`	Adds `isolatedDeclarations` optional boolean flag (default `false`) to the configuration schema, and conditionally applies `: any` type annotation to generated route constants when this flag is enabled with types.
Test Configuration `packages/router-generator/tests/generator.test.ts`	Registers a new test case configuration path for `isolated-declarations` to run the generator with the flag enabled.
Test Fixtures & Generated Snapshot `packages/router-generator/tests/generator/isolated-declarations/routes/__root.tsx`, `packages/router-generator/tests/generator/isolated-declarations/routes/index.tsx`, `packages/router-generator/tests/generator/isolated-declarations/routes/posts.tsx`, `packages/router-generator/tests/generator/isolated-declarations/routeTree.snapshot.ts`	Provides test route fixtures and an auto-generated route tree snapshot demonstrating the output when `isolatedDeclarations` is enabled.

Poem

🐰 A flag so fine, isolatedDeclarations declared,
Type annotations added where routes are prepared,
Conditional logic, gentle and neat,
Making router generation more complete! ✨

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: adding a new isolatedDeclarations config option to router-generator, which is the primary feature introduced across all modified files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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github-actions · 2026-04-29T12:47:52Z

Bundle Size Benchmarks

Commit: d6decca41807
Measured at: 2026-04-29T14:28:02.557Z
Baseline source: history:d6decca41807
Dashboard: bundle-size history

Scenario	Current (gzip)	Delta vs baseline	Raw	Brotli	Trend
`react-router.minimal`	87.30 KiB	0 B (0.00%)	274.68 KiB	75.83 KiB	████████▁▁▁
`react-router.full`	90.80 KiB	0 B (0.00%)	286.19 KiB	79.00 KiB	▁▁▁▁▁▁▁▁███
`solid-router.minimal`	35.55 KiB	0 B (0.00%)	106.95 KiB	31.97 KiB	▁▁▁▁████▁▁▁
`solid-router.full`	40.28 KiB	0 B (0.00%)	121.16 KiB	36.16 KiB	▁▁▁▁▄███▄▄▄
`vue-router.minimal`	53.30 KiB	0 B (0.00%)	152.09 KiB	47.88 KiB	████████▁▁▁
`vue-router.full`	58.44 KiB	0 B (0.00%)	168.27 KiB	52.33 KiB	▁▁▁▁▁▁▁▁███
`react-start.minimal`	101.92 KiB	0 B (0.00%)	322.84 KiB	88.06 KiB	▁▁▁▁▁▁▁▁███
`react-start.full`	105.34 KiB	0 B (0.00%)	333.17 KiB	90.98 KiB	████████▁▁▁
`react-start.rsbuild.minimal`	101.45 KiB	0 B (0.00%)	325.78 KiB	87.12 KiB	▁▁▁▁▁▁▁▁███
`react-start.rsbuild.full`	104.76 KiB	0 B (0.00%)	336.47 KiB	89.88 KiB	▁▁▁▁▁▁▁▁███
`solid-start.minimal`	49.55 KiB	0 B (0.00%)	152.77 KiB	43.68 KiB	▁▁▁▁████▂▂▂
`solid-start.full`	55.33 KiB	0 B (0.00%)	169.68 KiB	48.71 KiB	▁▁▁▁▃███▅▅▅

Trend sparkline is historical gzip bytes ending with this PR measurement; lower is better.

coderabbitai

🧹 Nitpick comments (1)

packages/router-generator/tests/generator.test.ts (1)

124-126: Add one combo fixture to lock the disableTypes no-op contract.

Consider adding a dedicated folder/case for isolatedDeclarations: true + disableTypes: true so this behavior is snapshot-guarded going forward.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@packages/router-generator/tests/generator.test.ts` around lines 124 - 126,
Add a new combo fixture/case that sets both config.isolatedDeclarations = true
and config.disableTypes = true so the no-op contract for disableTypes is
snapshot-guarded; create a dedicated test folder/case name (e.g.,
"isolated-declarations-disable-types") in the generator fixtures and ensure the
test runner picks it up and a snapshot is committed to lock current behavior for
the combination, referencing the config object and the existing
'isolated-declarations' case handling to mirror how other combos are added.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@packages/router-generator/tests/generator.test.ts`:
- Around line 124-126: Add a new combo fixture/case that sets both
config.isolatedDeclarations = true and config.disableTypes = true so the no-op
contract for disableTypes is snapshot-guarded; create a dedicated test
folder/case name (e.g., "isolated-declarations-disable-types") in the generator
fixtures and ensure the test runner picks it up and a snapshot is committed to
lock current behavior for the combination, referencing the config object and the
existing 'isolated-declarations' case handling to mirror how other combos are
added.

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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📥 Commits

Reviewing files that changed from the base of the PR and between d6decca and 58b9ddf.

📒 Files selected for processing (7)

packages/router-generator/src/config.ts
packages/router-generator/src/generator.ts
packages/router-generator/tests/generator.test.ts
packages/router-generator/tests/generator/isolated-declarations/routeTree.snapshot.ts
packages/router-generator/tests/generator/isolated-declarations/routes/__root.tsx
packages/router-generator/tests/generator/isolated-declarations/routes/index.tsx
packages/router-generator/tests/generator/isolated-declarations/routes/posts.tsx

@ts-nocheck

…tants and header Three correctness gaps in the original PR: 1. RouteWithChildren constants (generated by buildRouteTreeConfig for parent routes with children) were missing ': any' annotations. Add isolatedDeclarations param to buildRouteTreeConfig and propagate it through recursive calls. 2. rootRouteWithChildren (generated when the root route has component piece files) was also missing ': any'. Apply the same conditional. 3. The default routeTreeFileHeader includes '// @ts-nocheck', which opts the generated file out of type-checking entirely — defeating the purpose of isolatedDeclarations mode. Automatically strip '// @ts-nocheck' from the header when isolatedDeclarations: true. Add 'isolated-declarations-nested' fixture to cover the WithChildren code path (PostsRouteWithChildren: any on line 92 of snapshot). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

@ts-nocheck

// @ts-nocheck is intentionally included in TanStack's default routeTreeFileHeader. Users who need isolatedDeclarations type-checking should configure a custom routeTreeFileHeader that omits it — that is the right locus of control, not the generator silently overriding it. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

schiller-manuel · 2026-04-29T18:58:39Z

This is an accepted tradeoff for projects that need isolatedDeclarations compliance

not really. this either needs to be fixed correctly or we cant support this

guru-irl · 2026-04-30T06:05:34Z

This is an accepted tradeoff for projects that need isolatedDeclarations compliance

not really. this either needs to be fixed correctly or we cant support this

@schiller-manuel Yep yep, this is a vibe coded draft. I'll update this with real code EOD

github-actions Bot added the package: router-generator label Apr 29, 2026

guru-irl marked this pull request as draft April 29, 2026 12:49

coderabbitai Bot reviewed Apr 29, 2026

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Gurupungav Narayanan Codespace and others added 2 commits April 29, 2026 13:44

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feat(router-generator): add isolatedDeclarations config option#7289

feat(router-generator): add isolatedDeclarations config option#7289
guru-irl wants to merge 3 commits intoTanStack:mainfrom
guru-irl:feat/router-generator-isolated-declarations

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Summary

Solution

Type safety tradeoff

Test plan

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