feat(webapp): add RUNTIME_API_ORIGIN to decouple runner traffic from external origin

[ThullyoCunha]

Closes #2821

✅ Checklist

• I have followed every step in the contributing guide
• The PR title follows the convention.
• I ran and tested the code works

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Summary

The webapp publishes API_ORIGIN to runner pods as TRIGGER_API_URL, so runner-to-webapp traffic flows back through whatever URL is configured for external clients. Self-hosting behind a tracing-enabled gateway (Envoy, Istio, kgateway, ...) breaks the parent->child run link in trigger.dev's run-detail tree because the gateway's W3C traceparent rewrite on egress overwrites the SDK's triggerAndWait() span id. The webapp then writes that gateway-generated span id as the child run's parentSpanId, which never reaches the trigger event store, so the child renders as an orphan in the UI.

We hit this on our self-hosted v4 cluster running kgateway with tracing enabled (spawnUpstreamSpan: true). Reproduced with three rounds of SDK debug instrumentation (capturing the active span at propagation.inject, the wire undici:request:headers payload, and the value the webapp receives at the route level) plus a direct curl bypassing each hop until we isolated kgateway as the rewriter. Details on the investigation are in #2821 — several self-hosted users report the same symptom.

This PR splits the two concerns without sacrificing external auth/callbacks/UI flows that rely on the public API_ORIGIN:

• Set RUNTIME_API_ORIGIN=http://<service>.<namespace>:<port> (k8s) or http://webapp:3000 (docker) to keep runner->webapp traffic on a cluster-internal hop that bypasses the gateway.
• Leave API_ORIGIN on the public URL so the dashboard, magic-link emails, waitpoint callbacks, and API apiUrl responses keep working for external clients.

The new env is optional and falls back to API_ORIGIN/APP_ORIGIN, so existing deployments are unaffected.

Changes

• apps/webapp/app/env.server.ts: new optional RUNTIME_API_ORIGIN env.
• apps/webapp/app/v3/environmentVariables/environmentVariablesRepository.server.ts: prefer RUNTIME_API_ORIGIN when resolving TRIGGER_API_URL/TRIGGER_STREAM_URL for both dev and prod runner pods, falling back to the existing chain.
• hosting/k8s/helm/values.yaml + templates/webapp.yaml: expose webapp.runtimeApiOrigin (defaults to empty -> existing behavior).
• hosting/docker/webapp/docker-compose.yml + hosting/docker/.env.example: same opt-in for docker self-host.

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Testing

Validated on our self-hosted v4 staging cluster (kgateway + Envoy tracing).

Before (runners going through public URL, gateway rewrites traceparent):

• Parent runner SDK triggerAndWait() wrapper spanId: 070bcfdd63b42d2a (confirmed via wire-level undici:request:headers debug)
• Webapp receives traceparent with spanId: b8298ebb884ade7e (gateway-rewritten)
• Child TaskRun.parentSpanId = b8298ebb... (orphan: never in event store)

After (with apiOrigin pointed at the in-cluster service):

• Parent SDK injects spanId 66fa71fda94ccdb9
• Webapp receives spanId 66fa71fda94ccdb9 unchanged
• Child TaskRun.parentSpanId = 66fa71fda94ccdb9 matches the parent's triggerAndWait() event in TaskEvent table
• Run-detail tree renders the child nested under the parent, matching SaaS behavior

End-to-end test task at https://github.com/meistrari/trigger-self-tests/blob/main/src/tasks/link-test.ts (parent does linkTestChild.triggerAndWait(...)).

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Changelog

• webapp: add optional RUNTIME_API_ORIGIN env to advertise a runner-only API origin separate from API_ORIGIN. Lets self-hosted operators route runner-to-webapp traffic cluster-internally, bypassing tracing-enabled gateways that rewrite the W3C traceparent header on egress and break parent-to-child run linkage in the trace tree. Optional and backward-compatible (falls back to existing API_ORIGIN/APP_ORIGIN).
• hosting/k8s/helm + hosting/docker: expose the new env via webapp.runtimeApiOrigin (Helm) and RUNTIME_API_ORIGIN (docker-compose).

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Screenshots

N/A — no UI change. The visible effect is the run-detail tree correctly showing child task runs nested under their parent's triggerAndWait() span (matching trigger.dev SaaS behavior).

💯

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Walkthrough

This PR adds a new optional RUNTIME_API_ORIGIN environment variable to support self-hosted deployments where traffic routes through tracing-aware gateways. The variable is defined in the environment schema with normalization for empty strings, documented in Docker Compose configuration, and wired into Helm values and the webapp container template via conditional rendering. The value allows operators to specify an in-cluster origin that takes precedence in runner URL resolution.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~4 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title clearly describes the primary change: adding RUNTIME_API_ORIGIN to separate runner traffic from the external origin.
Description check	✅ Passed	Description comprehensively covers the problem, solution, testing results, and changes. All required template sections are addressed with detailed explanations.
Linked Issues check	✅ Passed	Changes fully address issue #2821 by implementing RUNTIME_API_ORIGIN to allow runners to bypass tracing-enabled gateways and preserve W3C traceparent span linkage.
Out of Scope Changes check	✅ Passed	All changes are scoped to implementing RUNTIME_API_ORIGIN configuration across webapp, Helm, and Docker deployment artifacts per the objective.
Docstring Coverage	✅ Passed	Docstring coverage is 80.00% which is sufficient. The required threshold is 80.00%.

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[devin-ai-integration]

Devin Review found 1 new potential issue.

🐛 1 issue in files not directly in the diff

🐛 RUNTIME_API_ORIGIN not passed through in docker-compose.yml, making the feature inoperative for Docker self-hosting (hosting/docker/webapp/docker-compose.yml:45)

The env.server.ts comment at line 136-137 explicitly references ${RUNTIME_API_ORIGIN:-} passthroughs in docker-compose.yml, and the .env.example documents RUNTIME_API_ORIGIN as a user-configurable option (hosting/docker/.env.example:57). However, hosting/docker/webapp/docker-compose.yml does not include RUNTIME_API_ORIGIN in its environment: section (lines 42-85). Docker Compose only passes env vars to containers that are explicitly listed in the environment: block — values from .env are used for variable substitution in the compose file, not automatically forwarded as container env vars. As a result, Docker self-hosting users who set RUNTIME_API_ORIGIN in their .env file will find it has no effect; the webapp container never receives the value, and runners will continue using API_ORIGIN/APP_ORIGIN. The Helm chart (hosting/k8s/helm/templates/webapp.yaml:189-192) correctly handles this, but the Docker path is broken.

View 4 additional findings in Devin Review.