docs(start): document route and asset base paths

[whizzkid1452]

Summary

• Explain that Vite base prefixes asset URLs while Start router.basepath prefixes application routes and server functions.
• Add examples for matching route and asset prefixes and for serving them from separate paths.
• Add the Base Paths guide to the React and Solid Start navigation.

Closes #4888

Test plan

• pnpm test:docs
• Validate docs/start/config.json with JSON.parse
• Format the changed files with Prettier
• Run affected ESLint, type, unit, and build targets against upstream/main (no affected projects for this documentation-only change)

Summary by CodeRabbit

• Documentation
  • Added a new Base Paths guide covering asset prefixes, application routes, server functions, deployment patterns, and verification steps.
  • Added Base Paths navigation entries for React and Solid framework documentation.
  • Linked the Solid guide to the shared Base Paths documentation.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds Base Paths documentation describing Vite asset prefixes and router route prefixes, provides a Solid reference to the React guide, and links both guides from framework navigation.

Changes

Base Paths Documentation

Layer / File(s)	Summary
Base path configuration guide docs/start/framework/react/guide/base-paths.md, docs/start/framework/solid/guide/base-paths.md	Adds the React Base Paths guide and a Solid reference to it, covering configuration patterns, URL mappings, and verification steps.
Framework navigation integration docs/start/config.json	Adds Base Paths entries to the React and Solid Server & Execution navigation sections.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Possibly related PRs

• TanStack/router#7864: Restructures the same documentation navigation tree modified by this PR.

Suggested labels: documentation

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the doc update about base paths for routes and assets.
Linked Issues check	✅ Passed	The new guides document Vite base, router.basepath, route and asset prefixes, and the deployment patterns requested by #4888.
Out of Scope Changes check	✅ Passed	The changes stay within documentation and navigation updates for base paths, with no unrelated code or config changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 Checkov (3.3.8)

docs/start/config.json

Traceback (most recent call last):
File "/usr/local/bin/checkov", line 2, in
from checkov.main import Checkov
ModuleNotFoundError: No module named 'checkov'

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@docs/start/framework/react/guide/base-paths.md`:
- Around line 38-46: Update the base-paths documentation around the URL table to
define serverFns.base in the preceding configuration example, or explicitly
document its default value and how it combines with router.basepath for
server-function URLs. Ensure the table’s server-function prefix source is
understandable from the surrounding text.

In `@docs/start/framework/solid/guide/base-paths.md`:
- Around line 1-2: Update the Solid base-paths guide referenced by its
frontmatter so it no longer serves the React guide verbatim. Make the shared
explanation framework-neutral and replace React-specific configuration such as
`@tanstack/react-start/plugin/vite`, `@vitejs/plugin-react`, and viteReact() with
valid Solid-specific examples.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 4dff169e-ef4e-4413-b9ca-3c9c6365acd8

📥 Commits

Reviewing files that changed from the base of the PR and between a76c192 and ec92b3a.

📒 Files selected for processing (3)

• docs/start/config.json
• docs/start/framework/react/guide/base-paths.md
• docs/start/framework/solid/guide/base-paths.md

[coderabbitai]

🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Define serverFns.base before using it in the URL table.

The table introduces serverFns.base as part of the server-function URL, but neither example defines it nor explains its default or composition with router.basepath. Add the relevant configuration or document the default and composition explicitly.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@docs/start/framework/react/guide/base-paths.md` around lines 38 - 46, Update
the base-paths documentation around the URL table to define serverFns.base in
the preceding configuration example, or explicitly document its default value
and how it combines with router.basepath for server-function URLs. Ensure the
table’s server-function prefix source is understandable from the surrounding
text.

[coderabbitai]

🎯 Functional Correctness | 🟠 Major | 🏗️ Heavy lift

Make the Solid guide framework-specific before exposing it.

This reference serves the React guide verbatim, including @tanstack/react-start/plugin/vite, @vitejs/plugin-react, and viteReact(). Solid users cannot safely copy that configuration. Keep the shared explanation framework-neutral or add Solid-specific examples.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@docs/start/framework/solid/guide/base-paths.md` around lines 1 - 2, Update
the Solid base-paths guide referenced by its frontmatter so it no longer serves
the React guide verbatim. Make the shared explanation framework-neutral and
replace React-specific configuration such as `@tanstack/react-start/plugin/vite`,
`@vitejs/plugin-react`, and viteReact() with valid Solid-specific examples.