[ewanharris]

Refs #22
Refs #23

Extensions run the server on the Node their editor ships. VS Code 1.100 is Electron 34 and Pulsar is Electron 32, and both are Node 20.18. A floor of 22 meant every user of either editor installing a newer Node before the server would start. This lowers the floor to 20.18. Day to day development and the test matrix don't change.

What changed

• Map.groupBy → a loop in core/tiapp.ts. It was the only Node 21+ API the server used.
• Node 20's types. @tsconfig/node20 sets the library to ES2023, and @types/node is pinned to ~20.17 (there's no 20.18 release of it). A newer API is now a compile error in npm run build and in the lint job, rather than a crash in an editor.
• engines is >=20.18.
• A Node 20 compatibility CI job builds on Node 20.18, starts out/server.js, and checks it answers initialize. tsc checks the API surface; this checks that what tsc emitted loads and runs there. That is all it does. The suite runs the sources through type stripping, which Node 20 lacks, so tests stay on 22 and 24.
• AGENTS.md says where the floor comes from and what holds it there.

Why 20.18 and not 20.11

20.11 is what import.meta.dirname needs, so I tried that first. Pinning the types to 20.11 found Dirent.parentPath in core/fs.ts, which only arrived in 20.12. Neither runtime check would have caught it, because nothing in the smoke test reads a directory. 20.18 is what both editors ship, so it's the floor that matters.

Checked

What	Where	Result
The CI step, run exactly as written in the YAML	Node 20.18.0	answers initialize
The same step against a missing server	Node 20.20.2	fails at once, exit 1
tsc with Map.groupBy put back	Node 20 types	TS2550
The whole compiled suite, as a one-off (not in CI)	Node 20.18.0	1219/1219
npm test	Node 22	1219/1219, above the coverage floor
npm run test:package	Node 22	10/10
Lint	—	clean

🤖 Generated with Claude Code

https://claude.ai/code/session_01AAKDFVwAZoxefLNvX45pE4

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Generated by Claude Code

[Copilot]

🟡 Changes recommended

The lockfile has an inconsistent engine floor, and module grouping introduces quadratic copying.

1 open finding

• Avoid quadratic module grouping from repeated bucket copying · New

What changed in this PR

Lowers runtime support to Node 20.18 for editor compatibility while retaining newer development environments.

Changes:

• Targets Node 20 APIs and replaces Map.groupBy.
• Adds a Node 20.18 initialization smoke test.
• Documents the runtime/development version split.

File	Description
tsconfig.json	Targets Node 20 configuration.
src/​core/​tiapp.ts	Replaces unsupported grouping API.
package.json	Lowers engine floor and pins Node 20 types.
package-lock.json	Updates dependency resolutions.
AGENTS.md	Documents Node compatibility constraints.
.github/​workflows/​ci.yml	Adds Node 20.18 smoke testing.

🧠 Review effort: Balanced

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