[rush-serve-plugin] The auto-picked port never reaches the port parameter: _value is ignored since ts-command-line uses #value #6144

Summary

When rush start (or another watch-mode phased command with portParameterLongName) runs without an explicit port, @rushstack/rush-serve-plugin listens on an OS-assigned port and then tries to publish it through the command-line parameter, so that other plugins (and the operations that receive the parameter) see the real port. It does so by writing portParameter._value. Since @rushstack/ts-command-line switched parameters to native private fields (#5943), CommandLineIntegerParameter stores its value in #value, so the assignment only adds an unused property. portParameter.value stays undefined, and nothing downstream sees the port.

Versions

• @microsoft/rush / @rushstack/rush-serve-plugin 5.181.0
• @rushstack/ts-command-line 5.3.17 (any version that includes Use native private members in core tooling #5943)
• Node.js 22

Repro

1. Configure rush-serve-plugin with portParameterLongName: "--port", and define --port as an integer parameter of the start command, associated with a phase.
2. Add a second plugin that taps createOperationsAsync after the serve plugin (any stage above -1) and logs context.customParameters.get('--port').value.
3. Run rush start without --port.

Expected

The serve plugin logs Content is being served from: https://localhost:<port>/, and the second plugin logs the same <port>.

Actual

The second plugin logs undefined. An explicit --port 4321 works, because then the value comes from the parser.

Code pointer (main)

• rush-plugins/rush-serve-plugin/src/phasedCommandHandler.ts, line 241: (portParameter as unknown as { _value?: string })._value = `${activePort}`;
• libraries/ts-command-line/src/parameters/CommandLineIntegerParameter.ts: the value lives in #value and is written only by _setValue().

Suggested fix

Set the value through the parameter's setter (it also stores a number, as the integer parameter expects, instead of a string):

(portParameter as unknown as { _setValue(data: unknown): void })._setValue(activePort);

Since _setValue is @internal, a public way for a plugin to override a parsed parameter value (or a session-level API that publishes the serve plugin's active port) would avoid the cast. A unit test that runs the handler with port 0 and checks portParameter.value would catch a regression.

Filed with help from GitHub Copilot (AI); reviewed by the reporter.