Add endpoint option to trace-plugin target property

[lsk567]

Summary

• Adds an optional endpoint field to the trace-plugin target property
• When specified, generates setenv("TRACE_PLUGIN_ENDPOINT", "<url>", 1) in main() before lf_reactor_c_main(). The environment variable gets read by the trace plugin at runtime, allowing it to stream data to the right destination.

Usage

target C {
    tracing: true,
    trace-plugin: {
        package: "lf-trace-xronos",
        library: "lf::trace-impl",
        endpoint: "http://192.168.1.100:4317" // optional. Only needed when the trace dashboard runs on a separate machine.
    }
}

Test plan

• Build and run an LF program with endpoint specified, verify the environment variable is set

🤖 Generated with Claude Code. Edited with ❤️ by @lsk567.

[Copilot]

Pull request overview

Adds support for configuring an optional trace-plugin endpoint via the trace-plugin target property, so generated C code can pass the endpoint to the runtime trace plugin through an environment variable.

Changes:

• Extend trace-plugin dictionary schema to accept an optional endpoint field.
• Emit setenv("TRACE_PLUGIN_ENDPOINT", ...) early in generated C entrypoints when an endpoint is configured.
• Conditionally include <stdlib.h> in generated C includes to support setenv().

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
core/src/main/java/org/lflang/target/property/TracePluginProperty.java	Adds endpoint to the trace-plugin dictionary spec and AST (de)serialization.
core/src/main/java/org/lflang/generator/c/CPreambleGenerator.java	Conditionally includes <stdlib.h> when tracing is enabled and an endpoint is provided.
core/src/main/java/org/lflang/generator/c/CMainFunctionGenerator.java	Generates setenv("TRACE_PLUGIN_ENDPOINT", ...) statements in generated main()/setup().

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