COM-191 - prefill CloudFormation template params in Launch Stack link

[rossnelson]

Summary

The serverless worker deployment "Launch Stack" button (CloudFormation, under the "I don't have a role yet" accordion) previously linked to a bare CloudFormation console URL and prefilled nothing. This wires the form's field values into the launch URL using AWS's param_<ParameterName>=<value> convention so the CloudFormation quick-create form opens with the template and parameters prefilled.

Changes

compute-fields.svelte: launchStackHref is now a $derived.by() that, when cfnTemplateUrl is set, builds a #/stacks/quickcreate?templateURL=... URL and appends:

• param_AssumeRoleExternalId from roleExternalId
• param_LambdaFunctionARNs from lambdaArn

RoleName is left to the template default (no form field exists for it). Each param_* entry is omitted when its source field is empty, and the template URL plus every param value are encodeURIComponent-encoded. When cfnTemplateUrl is falsy, the existing bare-console fallback is preserved.

Decisions worth a look

• RoleName: left at the template default since there is no form field for it. Easy to expose a role-name input if we want one.
• quickcreate vs create/review: used #/stacks/quickcreate for the prefilled-but-editable UX. Can pin to #/stacks/create/review for strict parity with the S3 export / Kinesis audit-log forms if preferred.

Notes for the integrator (out of scope here)

End-to-end this requires cloud-ui to pass a real, publicly-hosted cfnTemplateUrl and repack the tarball. The local temporal-worker-role.yaml is download-only and currently has no Parameters section; the parameterized hosted template is handled separately in cloud-ui.

Test plan

• pnpm check clean
• pnpm lint clean
• Verified generated href for sample inputs contains the encoded templateURL, param_AssumeRoleExternalId, and param_LambdaFunctionARNs, and omits empty params

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Project	Deployment	Actions	Updated (UTC)
holocene	Ready	Preview, Comment	Jun 30, 2026 8:05pm