Revert template state model

[sjmiller609]

Summary

• revert the template VM state, API endpoints, and metadata fields
• remove template-specific fork and deletion behavior so snapshot fanout can replace it

Tests

• go test ./lib/instances/ -run 'Test(StateTransitions|ResolveForkTargetState|ValidateForkRequest|ForkInstanceFromStandbyCancelsCompressionJobAndCopiesRawMemory)'\n- go test ./cmd/api/api ./lib/scopes ./lib/builds (fails locally: bridge setup is not permitted and mkfs.erofs is unavailable)

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Note

Medium Risk
Removes the Template lifecycle state and associated API endpoints, which is a breaking change for clients and alters fork/delete/restore behavior for standby instances. Risk is moderate due to lifecycle semantics and generated OpenAPI client/server surface changes.

Overview
Reverts the template instance concept by removing the Template state from instances (state machine, metadata fields, state derivation, and transition tests) and deleting all template-specific logic such as fork-from-template handling and delete/demote fork-count guards.

Removes the POST /instances/{id}/promote-template and POST /instances/{id}/demote-template endpoints end-to-end (API handlers, scopes, OpenAPI schema/enum, generated lib/oapi client/server code, and stainless.yaml), and drops the now-obsolete template-focused unit test suite.

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[github-actions]

✱ Stainless preview builds for hypeman

This PR will update the hypeman SDKs with the following commit message.

feat: Revert template state model

✅ hypeman-openapi studio · code

Your SDK build had at least one "note" diagnostic.
generate ✅

⚠️ hypeman-typescript studio · code

Your SDK build had a failure in the lint CI job, which is a regression from the base state.
generate ✅ → build ✅ → lint ❗ → test ✅

✅ hypeman-go studio · code

Your SDK build had at least one "note" diagnostic.
generate ✅ → build ⏭️ → lint ✅ → test ✅

go get github.com/stainless-sdks/hypeman-go@537a68947307effc1c8a9efec8a9041fd6319e9d

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Last updated: 2026-05-18 14:39:18 UTC

[firetiger-agent]

Monitoring Plan: Remove Template Instance State

This PR removes the Template VM instance state and its associated PromoteInstanceToTemplate / DemoteInstanceTemplate API endpoints entirely. The change deletes ~1,400 lines across the instance manager, state machine, API handlers, OpenAPI spec, and OAPI client — cleaning up an unused lifecycle concept. After this deploy, instances with IsTemplate=true in stored metadata will be read back as plain Standby (since deriveState no longer checks IsTemplate), and callers hitting the removed endpoints will receive 404s.

Key risks to watch post-deploy: (1) any existing Template-state instances whose metadata is read back and misclassified, triggering unexpected state transitions; (2) a spike in 4xx/5xx errors on /instances/{id}/fork, /instances/{id}/restore, or the removed paths; (3) any panics or invalid_state errors in the API logs from code paths that still referenced StateTemplate but weren't caught by the test suite. Status updates will be posted automatically on this PR as monitoring progresses.

Key risks:

• Fork/restore 5xx errors rising above baseline (~0.01–0.018%)
• invalid_state or failed to promote/demote errors appearing in API logs post-deploy
• 404s on /instances/{id}/promote-template or /instances/{id}/demote-template (expected/benign if callers already migrated, but volume worth confirming is zero)
• Metadata misread: instances previously in Template state now incorrectly treated as Standby

View agent