make rvn-stack workspace settings immutable

[flybayer]

Greptile Summary

This PR marks two Terraform state backend workspace settings — use_ravion_state_backend and ravion_state_backend_workspace — as immutable: true in the rvn-stack-definition.yml module definition, preventing users from changing the state backend configuration after a stack is initially created.

• use_ravion_state_backend (boolean, default true) is now locked at creation time, preventing any switch between Ravion-managed state and a self-managed backend after deployment.
• ravion_state_backend_workspace (string, optional, no default in YAML) is also locked; since the field is only visible when use_ravion_state_backend is true, it must be set during initial configuration or it will remain unset permanently.

Confidence Score: 4/5

Safe to merge with a minor clarification needed: the optional workspace name field can be permanently left unset once immutability is enforced.

The change is minimal and intentional — locking the Terraform state backend settings prevents dangerous mid-lifecycle state migrations. The only concern is that ravion_state_backend_workspace, being optional and shown only conditionally, could end up permanently unset if a user skips it at creation time. Whether this is acceptable depends on how the platform handles the absence of this field at runtime.

stack/terraform/rvn-stack-definition.yml — specifically the interaction between immutable: true and the optionality of ravion_state_backend_workspace.

Important Files Changed

Filename	Overview
stack/terraform/rvn-stack-definition.yml	Adds immutable: true to use_ravion_state_backend and ravion_state_backend_workspace workspace settings to prevent changes after initial configuration.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[User creates stack] --> B{use_ravion_state_backend?}
    B -- "true (default)" --> C[Ravion manages state backend]
    B -- "false" --> D[User manages own backend]
    C --> E{ravion_state_backend_workspace set?}
    E -- "yes" --> F[Use custom workspace name]
    E -- "no" --> G[Use default: project+env+module ids]
    F --> H[🔒 immutable: true — cannot change]
    G --> H
    D --> I[🔒 immutable: true — cannot change]
    C --> I2[🔒 immutable: true — cannot change]

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flowchart TD
    A[User creates stack] --> B{use_ravion_state_backend?}
    B -- "true (default)" --> C[Ravion manages state backend]
    B -- "false" --> D[User manages own backend]
    C --> E{ravion_state_backend_workspace set?}
    E -- "yes" --> F[Use custom workspace name]
    E -- "no" --> G[Use default: project+env+module ids]
    F --> H[🔒 immutable: true — cannot change]
    G --> H
    D --> I[🔒 immutable: true — cannot change]
    C --> I2[🔒 immutable: true — cannot change]

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Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
stack/terraform/rvn-stack-definition.yml:123-130
**Immutable optional field may be permanently unset**

`ravion_state_backend_workspace` has no `required: true` and no `default` value set in the YAML. Once it is marked `immutable: true`, a user who skips setting this field during initial stack creation can never populate it afterward. This is likely intentional since the system resolves it to `project + environment + module` IDs at runtime, but it is worth verifying that the immutability guard is only applied after the field has been given an opportunity to be set (i.e., when `use_ravion_state_backend` is `true` and the form is visible).

_{Reviews (1): Last reviewed commit: "make rvn-stack workspace settings immuta..." | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

[github-actions]

Ravion Module Publish Plan

Dry run only. No Ravion API mutations were made.

Module	Current Version	New Version	Description
rvn-stack	1.2.3	1.2.4	Make the stack backend settings immutable

Diffs

rvn-stack 1.2.3 -> 1.2.4

--- remote
+++ compiled
   - default: true
     description: Use Ravion-managed state. Your Terraform configuration must include an empty `terraform { cloud {} }` block; Ravion supplies the workspace configuration. Disable to use your own backend, including S3 or Terraform Cloud.
     id: use_ravion_state_backend
+    immutable: true
     label: Use Ravion for your Terraform state
     type: boolean
   - collapsible: true
     description: Override Terraform state backend workspace name. Defaults to project + environment + module given ids.
     id: ravion_state_backend_workspace
+    immutable: true
     label: Ravion Terraform workspace name
     show_when:
       use_ravion_state_backend: true