feat(fleet): YAML tab for fleet plans (view + edit source inline)

[corey-aloia]

What

Adds a first-class YAML tab to the Fleet Plan detail view (Overview · Settings · Agents · YAML) for viewing and editing a plan's source inline, and removes the old "Import/Export YAML" toggle button that opened an empty editor and never saved.

Why the old button was broken

A fleet plan row stores two columns: definition (the JSON source of truth every other tab and execution reads) and yaml_content (a separate raw string). Platform mode never reconciled them:

• GetPlanYAML returned only yaml_content, which is empty for any plan created in the UI → blank editor.
• SavePlanYAML wrote only yaml_content; it never parsed the YAML back into definition, so edits never reached the other tabs or execution.

Changes

Backend — pkg/store/entstore/team_fleet.go:

• GetPlanYAML serializes definition → YAML (healing name/key from the row columns), so the tab always matches the other tabs and is never blank. Falls back to yaml_content only if marshalling fails.
• SavePlanYAML parses the YAML, runs Validate() (errors surface as HTTP 400 in the editor), reconciles into definition via Save(), and also stores the raw text.

Frontend:

• fleetHooks.ts — accept yaml as a valid detail tab (hash routing).
• FleetConfigEditor.tsx — FleetDetailTabs takes an optional tabs prop; templates keep three tabs, only plans opt into YAML.
• PlanDetail.tsx — render the YAML editor as a full-height tab; remove the toggle button, its state, and the bottom-dock render.

Scope is fleet plans only — fleet templates have no yaml_content column or YAML endpoint.

Tests

• Go (team_fleet_plan_test.go): GetPlanYAML from definition-only rows (blank-editor regression), name healing from the column, SavePlanYAML reconciliation into definition, and validation of invalid/name-less YAML.
• Vitest (fleetHooks.test.ts): the yaml tab is accepted from the hash.
• Verified in-browser (Studio, platform mode): tab appears, editor is populated, valid save reflects in Overview, invalid YAML returns a 400 without corrupting the plan, old button gone.

go build ./... clean; full Vitest suite (737 tests) green.

resolves #555

[cla-assistant]

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1 out of 2 committers have signed the CLA.

✅ corey-aloia
❌ rschardosin
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[rschardosin]

Thank you!