feat(nexus-operations): standalone nexus operation commands (start/cancel/terminate) [DT-4008]

[rossedfort]

Description & motivation 💭

Adds the three command actions for standalone nexus operations: Request Cancellation, Terminate, and Start Nexus Operation Like This One (start form). This is Phase 6 of the standalone nexus operations feature, building on the details page (DT-4002).

What changed

Cancel/Terminate confirmation modals (cancel-confirmation-modal.svelte, terminate-confirmation-modal.svelte):

• Cancel modal calls cancelNexusOperationExecution and shows a confirmation dialog with no extra input
• Terminate modal calls terminateNexusOperationExecution and includes an optional reason text input
• Both show toast on success and call onConfirm to trigger a live poll refresh + abort

Actions menu (nexus-operation-actions.svelte):

• "Request Cancellation" primary button — disabled when operation is not in RUNNING state
• "More Actions" dropdown with "Terminate" (destructive, disabled when not running) and "Start Nexus Operation Like This One"
• "Start Like This One" navigates to the start form pre-filled with endpoint/service/operation/operationId query params

Header wiring (nexus-operation-header.svelte):

• Added poller: StandaloneNexusOperationPoller prop
• Wired NexusOperationActions into the header flex row with ml-auto

Start nexus operation form (start-standalone-nexus-operation-form/form.svelte, types.ts):

• Fields: Operation ID (with random UUID button), Endpoint, Service, Operation Name
• Single payload input with encoding selector
• Timeouts card: Start To Close (required if no Schedule To Close), Schedule To Close (required if no Start To Close), Schedule To Start — with cross-field validation
• Advanced options toggle: Nexus Header key-value pairs, Search Attributes, User Metadata (summary + details markdown), ID Policies (reuse + conflict)
• On success: toast with link to the newly created operation detail page
• Pre-fills from URL query params (operationId, endpoint, service, operation)

Start page + route (start-standalone-nexus-operation.svelte, nexus-operations/start/+page.svelte):

• Back link to nexus operations list (preserving search params)
• Page title and route at /namespaces/[namespace]/nexus-operations/start

Screenshots (if applicable) 📸

No screenshots — UI follows existing patterns (activity start form, workflow cancel/terminate modals).

Design Considerations 🎨

• Start form mirrors start-standalone-activity-form/form.svelte exactly in structure, adapted for nexus-specific fields (endpoint/service/operation instead of task queue, nexus header section, no heartbeat/retry policy)
• Cancel/terminate modals mirror the workflow cancel/terminate pattern
• Actions button layout matches the workflow detail page actions pattern

Testing 🧪

How was this tested 👻

• Manual testing
• E2E tests added
• Unit tests added

Steps for others to test: 🚶🏽‍♂️🚶🏽‍♀️

1. Navigate to a namespace with standalone nexus operations enabled
2. Open a running nexus operation detail page
3. Verify "Request Cancellation" button is enabled; confirm the modal and check the operation status updates
4. Verify "More Actions > Terminate" is enabled for running operations; confirm the modal with an optional reason
5. Click "Start Nexus Operation Like This One" — verify the start form opens pre-filled with the operation's endpoint/service/operation/operationId
6. Submit the start form — verify toast appears with a link to the new operation detail page
7. For a non-running operation, verify both Cancel and Terminate actions are disabled

Checklists

Draft Checklist

• Type check passes (pnpm check --threshold error — only 2 pre-existing errors in package/ files)
• Lint clean for all new files
• Follows existing component patterns

Merge Checklist

• E2E test coverage for cancel/terminate/start flows
• Design review

Issue(s) closed

DT-4008

Docs

Any docs updates needed?

No docs updates needed — this is UI-only feature work for an existing API.

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Project	Deployment	Actions	Updated (UTC)
holocene	Ready	Preview, Comment	Jun 5, 2026 7:10pm