docs(switch): clarify mTLS service selection

[jayzhudev]

Document how switch_mtls_services and nmx_cluster_switch_mtls_services select switch mTLS certificate bindings. Clarify each setting's workflow, target, defaults, replacement behavior, accepted values, and binding targets.

Related issues

Resolves #5038

Type of Change

• Add - New feature or capability
• Change - Changes in existing functionality
• Fix - Bug fixes
• Remove - Removed features or deprecated functionality
• Internal - Internal changes (refactoring, tests, docs, etc.)

Breaking Changes

• This PR contains breaking changes

Existing configuration defaults remain unchanged.

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• No testing required (docs, internal refactor, etc.)

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📥 Commits

Reviewing files that changed from the base of the PR and between abc0b31 and 1b5e277.

📒 Files selected for processing (1)

• deploy/nico-base/api/config-files/carbide-api-config.toml

🚧 Files skipped from review as they are similar to previous changes (1)

• deploy/nico-base/api/config-files/carbide-api-config.toml

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Summary by CodeRabbit

• Documentation
  • Clarified configuration options for selecting mTLS services used by rack and switch state controllers.
  • Documented supported services, default selections, replacement behavior, and handling of empty or omitted lists.
  • Explained that service selection requests certificate bindings but does not enable the services.
  • Updated state-machine references for clearer guidance on rack and switch certificate configuration.

Walkthrough

The pull request updates configuration and architecture documentation for rack and switch mTLS service selection. It documents defaults, supported service values, replacement behavior, certificate binding targets, and the distinction between selecting bindings and enabling services.

Changes

mTLS service selection documentation

Layer / File(s)	Summary
Configuration reference updates crates/api-core/src/cfg/README.md, deploy/nico-base/api/config-files/carbide-api-config.toml	The configuration references document rack and switch mTLS service lists, default values, supported services, list replacement behavior, and service enablement semantics.
Certificate workflow reference docs/architecture/state_machines/switch_configure_certificate.md	The workflow documentation distinguishes switch and rack service lists, maps service values to certificate bindings, and links the rack state machine documentation.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 1b5e2

This PR clarifies mTLS service-selection documentation and preserves existing configuration defaults; no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The PR also adds and updates rack state-controller mTLS documentation, which is outside the switch-focused scope of #5038.	Remove rack-specific documentation changes or link an issue that explicitly requires rack state-controller mTLS documentation.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the primary change: clarifying switch mTLS service selection.
Description check	✅ Passed	The description directly explains the documented configuration behavior and identifies the related issue.
Linked Issues check	✅ Passed	The PR documents all switch mTLS service-selection requirements from #5038, including scope, defaults, replacement behavior, and binding-only semantics.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Actionable comments posted: 1

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Inline comments:
In `@deploy/nico-base/api/config-files/carbide-api-config.toml`:
- Around line 121-122: Update the switch_state_controller comment to refer to
the four SwitchMtlsService values instead of SwitchService, matching the
configuration contract documented by the referenced type.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 880221f8-2adb-4d33-8a9c-799eb9a5d2d5

📥 Commits

Reviewing files that changed from the base of the PR and between 2d3b497 and abc0b31.

📒 Files selected for processing (3)

• crates/api-core/src/cfg/README.md
• deploy/nico-base/api/config-files/carbide-api-config.toml
• docs/architecture/state_machines/switch_configure_certificate.md