Read $KUBECONFIG env var in kubectl generator

[lucieleblanc]

Summary

Read $KUBECONFIG environment variable in kubectl_script() and pass it to kubectl commands when --kubeconfig is not explicitly specified in the command tokens. This enables resource completions for users who set KUBECONFIG in their shell environment, which is common for multi-cluster Kubernetes setups.

Fixes: warpdotdev/warp#3930
Linear: APP-3478

Changes

Updated kubectl_script() in command-signatures/src/generators/kubectl.rs to apply three levels of kubeconfig resolution:

1. --kubeconfig flag from command tokens (existing behavior, highest priority)
2. KUBECONFIG from inline command environment variables (e.g., KUBECONFIG=/path kubectl get pods)
3. $KUBECONFIG shell variable fallback for session-level env vars forwarded to the child process

Added a helper function env_var_value() to extract values from the KEY=VALUE formatted env vars list.

Testing

Context generator with --kubeconfig flag

Completions dropdown correctly shows staging-context and test-context from the kubeconfig file:

Unit Tests

Added 5 unit tests covering:

• --kubeconfig flag from tokens
• KUBECONFIG from inline env vars
• Flag takes precedence over env var
• Shell variable fallback when neither is specified
• env_var_value() helper function

All tests pass: cargo test -p warp-command-signatures -- kubectl → 5 passed.

script/presubmit passes (22 total tests).

---

Conversation: https://staging.warp.dev/conversation/53c00fa8-fb8d-4ba9-86c8-249585bbba02
Run: https://oz.staging.warp.dev/runs/019d4b05-7ecc-79df-b704-a3d601a24f4b
This PR was generated with Oz.

[linear]

APP-3478 [kubectl] Read $KUBECONFIG env var in generator

The kubectl generator currently only forwards --kubeconfig from tokens but doesn't read the $KUBECONFIG environment variable. Users who set KUBECONFIG in their shell (common for multi-cluster setups) get no resource completion.

Fix: read $KUBECONFIG env var in kubectl_script() in command-signatures/src/generators/kubectl.rs and pass it to kubectl commands.

See GitHub #3930

[lucieleblanc]

Context generator screenshot (--kubeconfig flag)

Testing kubectl --kubeconfig /tmp/kube-test/config config use-context + Tab:

The completions dropdown shows staging-context and test-context from the kubeconfig file, followed by flag completions.

[lucieleblanc]

Context generator with --kubeconfig flag

[lucieleblanc]

Context completions with session KUBECONFIG env var

[lucieleblanc]

Manually attached screenshots:
flag generator

empty generator

[lucieleblanc]

Manually attached screenshots: