fix: read templates off the LSP event loop - #1662
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megha-narayanan merged 2 commits intoJun 23, 2026
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Convert the two synchronous template reads on the LSP request paths (onDefinition and the CodeLens provider) to fs.promises, continuing the async direction from aws#1631. A blocking read stalled the single LSP event loop and delayed every other editor request. resourceTarget, codeLensesForFile, and commandFor are now async and read sequentially, so the number of concurrent reads never grows with app size. The LspHandlers interface widens onCodeLens and onDefinition to return Promises; the connection wiring passes the Promise through unchanged. readAssembly and the source-map reads stay synchronous: they run at startup and on watch events, not per request, and convert-source-map takes a synchronous reader.
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…p-async-io # Conflicts: # packages/@aws-cdk/cdk-explorer/test/lsp/server.test.ts
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Merges the`feat/cdk-lsp' branch into `main`. The change is additive and introduces no behavior change to existing CLI commands. - New `@aws-cdk/cdk-explorer` package containing the Language Server under `lib/lsp` (server, diagnostics, CodeLens, template locator, position mapping). - Extends `@aws-cdk/cloud-assembly-api` with two parsing modules consumed by the server: `construct-tree.ts` (builds the construct tree from a cloud assembly) and `template-ranges.ts` (resolves a logical ID or property to its byte range in the template). Capabilities (folds in aws#1559, aws#1593, aws#1592, aws#1617, aws#1624, aws#1630, aws#1631, aws#1662, aws#1634, aws#1674): - Diagnostics: surfaces synth errors and policy-validation violations in the editor, mapped back to the source. - Surfaces CFN resources and adds CodeLens navigation from a construct to its template resource. - Navigation between construct source and the synthesized template in both directions. - Live refresh: diagnostics and CodeLens update when `cdk.out` changes. - Reads are constrained to the project directory, and template reads run off the LSP event loop. This PR is the server and parsing foundation. It does not add a shipped CLI command or the web explorer. ### Checklist - [ ] This change contains a major version upgrade for a dependency and I confirm all breaking changes are addressed - Release notes for the new version: --- By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license --------- Signed-off-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Otavio Macedo <288203+otaviomacedo@users.noreply.github.com>
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Convert the two synchronous template reads on the LSP request paths (onDefinition and the CodeLens provider) to fs.promises, continuing the async direction from #1631.
resourceTarget, codeLensesForFile, and commandFor are now async and read sequentially, so the number of concurrent reads never grows with app size. The LspHandlers interface widens onCodeLens and onDefinition to return Promises; the connection wiring passes the Promise through unchanged.
readAssembly and the source-map reads stay synchronous: they run at startup and on watch events, not per request, and convert-source-map takes a synchronous reader.
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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license