Simplify and modernise tsdown build configuration

[smorimoto]

Summary

• Upgrade tsdown from 0.17 to 0.20 (rolldown 1.0.0-rc.3) and consolidate the build configuration from two separate objects (ESM and CJS) into a single unified configuration object
• Remove redundant options:
  • target — auto-inferred from engines.node
  • unbundle — unnecessary as only two entry points are exported, reducing output from 566 to 12 files
  • outExtensions — auto-derived by tsdown 0.20
• Replace noExternal with inlineOnly, the recommended tsdown 0.20 option that prevents unintended dependency bundling. Also fix the dependency list: remove uint8array-extras (recursively inlined via iron-webcrypto) and add the missing jose (direct ESM-only dependency)
• Add exports option with customExports to auto-manage package.json exports, keeping them in sync with build output. Runtime-specific conditions (workerd, edge-light, convex) route to the worker entry for environments without process global
• Remove deno and bun export conditions as both runtimes resolve correctly through the standard import/require fallback
• Remove explicit types fields from export conditions as co-located .d.mts/.d.cts files are resolved automatically by TypeScript
• Add publint validation to catch export mismatches on every build
• Add attw validation with node16 profile to verify type declarations on every build, replacing the separate check:types npm script which used --ignore-rules no-resolution
• Update ecosystem-check.ts to reference .mjs extensions matching tsdown 0.20 output

Package size comparison

Metric	Before (main)	After	Change
lib/ file count	2,449	18	-99.3%
lib/ disk size	9.1 MB	1.6 MB	-82.4%
npm pack (unpacked)	2.3 MB	1.6 MB	-30.4%
npm pack (.tgz)	399 KB	267 KB	-33.1%
Build time	1,407 ms	693 ms	-50.7%

Breaking change note

Removing unbundle means individual source files are no longer emitted to lib/. Deep imports such as @workos-inc/node/lib/common/net/node-client that previously worked (despite never being officially supported via the exports map) will no longer resolve. Only the documented entry points (. and ./worker) are available. This aligns the actual output with the package's public API surface.

Housekeeping

• Sort package.json fields with sort-package-json for consistent field ordering

Test plan

• npx tsdown builds successfully with no warnings
• publint reports no issues
• attw reports no problems (node16 CJS/ESM, bundler all green)
• npm run check:runtimes passes all 6 runtime tests (node-cjs, node-esm, deno, bun-cjs, bun-esm, worker)

[greptile-apps]

Greptile Overview

Greptile Summary

Consolidated and modernized the build configuration by upgrading tsdown from 0.17 to 0.20, replacing two separate build configs with a unified approach that reduces output from 566 to 12 files while maintaining full compatibility across Node.js, Deno, Bun, and Worker runtimes.

Key changes:

• Switched from unbundle: true with glob patterns to explicit entry points (src/index.ts, src/index.worker.ts)
• Replaced noExternal with inlineOnly and fixed the dependency list: added missing jose (direct ESM-only dependency) and removed uint8array-extras (transitively inlined via iron-webcrypto)
• Added exports.customExports to auto-manage package.json exports, routing runtime-specific conditions (workerd, edge-light, convex) to worker entry
• Removed redundant export conditions (deno, bun) and explicit types fields (auto-resolved by TypeScript)
• Added publint: true for export validation on every build
• Updated file extensions from .js to .mjs matching tsdown 0.20 output conventions

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The changes are well-tested infrastructure improvements to the build system. The PR author verified all 6 runtime tests pass (node-cjs, node-esm, deno, bun-cjs, bun-esm, worker), publint reports no issues, and the build completes successfully. The configuration changes align with tsdown 0.20 best practices and the dependency list corrections (jose added, uint8array-extras removed) are accurate based on the codebase analysis.
• No files require special attention

Important Files Changed

Filename	Overview
tsdown.config.ts	Modernized tsdown configuration from v0.17 to v0.20, replacing two separate configs with a unified build, switching to inlineOnly with correct dependencies (jose added, uint8array-extras removed), and adding publint validation
package.json	Updated dependencies (tsdown 0.17→0.20, added publint), changed file extensions to .mjs/.d.cts, simplified exports by removing redundant deno/bun conditions and explicit types fields
scripts/ecosystem-check.ts	Updated import paths from .js to .mjs extensions to match tsdown 0.20 output format

Flowchart

flowchart TD
    A[Source Files] --> B[tsdown 0.20]
    B --> C{Build Format}
    C -->|ESM| D[index.mjs<br/>index.worker.mjs]
    C -->|CJS| E[index.cjs<br/>index.worker.cjs]
    C -->|Types| F[index.d.cts<br/>index.worker.d.mts]
    
    G[Dependencies] --> H{Bundling Strategy}
    H -->|inlineOnly| I[iron-webcrypto<br/>jose]
    H -->|External| J[Other deps]
    
    I --> D
    I --> E
    J --> D
    J --> E
    
    D --> K[package.json exports]
    E --> K
    F --> K
    
    K --> L{Runtime Condition}
    L -->|workerd/edge-light/convex| M[worker entry]
    L -->|import| N[main ESM]
    L -->|require| O[main CJS]
    
    P[publint] --> K
    P --> Q[Validation]

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