Fix process spawn

[marcotc]

Fixes #5621

What does this PR do?

Motivation:

Change log entry

Additional Notes:

How to test the change?

[dd-octo-sts]

👋 Hey @marcotc, please fill "Change log entry" section in the pull request description.

If changes need to be present in CHANGELOG.md you can state it this way

**Change log entry**

Yes. A brief summary to be placed into the CHANGELOG.md

(possible answers Yes/Yep/Yeah)

Or you can opt out like that

**Change log entry**

None.

(possible answers No/Nope/None)

^{Visited at: 2026-04-23 00:38:31 UTC}

[dd-octo-sts]

Typing analysis

Note: Ignored files are excluded from the next sections.

Untyped methods

This PR introduces 1 untyped method and 2 partially typed methods, and clears 1 untyped method and 1 partially typed method. It decreases the percentage of typed methods from 61.33% to 61.28% (-0.05%).

Untyped methods (+1-1)

❌ Introduced:

sig/datadog/core/utils/spawn_monkey_patch.rbs:11
└── def spawn: (*untyped args) -> untyped

✅ Cleared:

sig/datadog/core/utils/spawn_monkey_patch.rbs:11
└── def spawn: (*untyped args, **untyped opts) -> untyped

Partially typed methods (+2-1)

❌ Introduced:

sig/datadog/core/utils/spawn_monkey_patch.rbs:8
└── def self.apply!: (env_provider: ^() -> ::Hash[::String, ::String]) -> untyped
sig/datadog/core/utils/spawn_monkey_patch.rbs:14
└── def self.inject_envs: (untyped args) -> ::Array[untyped]

✅ Cleared:

sig/datadog/core/utils/spawn_monkey_patch.rbs:14
└── def self.inject_lineage_envs: (untyped args) -> ::Array[untyped]

If you believe a method or an attribute is rightfully untyped or partially typed, you can add # untyped:accept on the line before the definition to remove it from the stats.

[Strech]

Suggested change

	def self.apply!: (env_provider: ^() -> ::Hash[::String, ::String]) -> untyped
	def self.apply!: (env_provider: ^() -> ::Hash[::String, ::String]) -> void

[mabdinur]

Thanks for opening this PR 😄.

Can we update the PR and add a changelog? Also we need to address some failing tests. I'd love to get this fix out as soon as possible

[mabdinur]

nit: We can improve clarity

Suggested change

	# Vessel for env_provider propagation.
	# Prepends Process.spawn to merge env_provider into the child env.

[mabdinur]

this should fix the failing tests

Suggested change

	read_io.read.lines.map { |line| line.chomp.split('=', 2) }.to_h
	read_io.read.lines.filter_map do |line|
	parts = line.chomp.split("=", 2)
	parts if parts.size == 2
	end.to_h

[ivoanjo]

Hey @mabdinur @marcotc since this is still an active regression, what's missing to land this?