fix: copy the config on browser creation instead of mutating the caller's

[nathanfallet]

Problem

DefaultBrowser.start() writes runtime state onto the Config it is given — it assigns host and port, and appends launch arguments:

val connectExisting = config.host != null && config.port != null
if (!connectExisting) {
    config.host = "127.0.0.1"
    config.port = freePort()          // writes into the caller's instance
}
...
if (!connectExisting) {
    process = startProcess(exe, params)   // only launched in this branch
}

So passing the same Config to a second browser makes it take the connectExisting branch: it never launches a browser process, and only tries to reach the previous one's port, which is dead by then. The start then fails after the full connect window, logging Browser process started with PID: null.

This bites anyone retrying a failed start with the same config, which is a natural thing to do.

Fix

DefaultBrowser now works on its own copy:

open class DefaultBrowser(
    val coroutineScope: CoroutineScope,
    config: Config,
) : Browser {
    override val config: Config = config.copy()

Copying rather than making Config immutable keeps this a small, non-breaking change: browser.config.port still returns the port actually in use, and no public API changes shape.

Config.copy() is deep where it matters, with three details worth noting:

• it duplicates the argument and extension lists, so mutating one config never affects the other;
• it passes the already-resolved browserExecutablePath, so the copy does not re-run the executable disk search;
• it copies the userDataDir backing field rather than the getter — reading the getter would materialise a temporary profile directory on a config that may never be started.

Tests

Three tests on Config.copy(): independence of args/host/port, no duplication of the default arguments across repeated copies, and correct userDataDir handling in both the custom and default cases.

ConfigDslTest.testCreateBrowserWithDslConfig asserted assertEquals(cfg, browser.config), which encoded the old instance-sharing behaviour. It now asserts the stronger contract: the browser holds a distinct copy, the values carry over, and the caller's config is left untouched (cfg.port stays null while browser.config.port is set).

Note: :core:build fails on kotlinStoreYarnLock on this branch, but it does so on main too — unrelated to this change. :core:jvmTest passes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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