decision(security): retain and harden or retire agentic command mode

[WalksWithASwagger]

Summary

Decide whether the optional agentic command-provider mode should be retained and hardened or removed after the GitHub-only migration.

Context

• Related migration: pipeline: disable retired Linear synchronization and remove its client #320 and pipeline: make branch and PR traceability GitHub-only #324.
• Roadmap phase: Phase 3 - workflow security
• Relevant files for later implementation: agentic/contract.json, .github/workflows/agentic-dev-loop.yml, scripts/agentic/provider_adapter.py, scripts/agentic/common.py, scripts/agentic/dev_loop.py, focused agentic tests, and docs/DELIVERY-PIPELINE.md
• Current behavior: the default provider is noop, but an optional repository-configured command can execute inside a checkout and may share workflow context with GitHub credentials.
• Desired behavior: maintainers explicitly choose retirement or a least-privilege hardening contract before command mode is used.

Implementation Notes

• This is a decision issue, not authorization to execute a provider command.
• If retiring, define the exact active contract/workflow/tests/docs to remove.
• If retaining, require checkout credentials not to persist, token-bearing steps to be fixed and isolated, provider environment to use an allowlist, remote validation before push, and tests that assert variable names only.

Acceptance Criteria

• KK records one decision: retire command mode or retain and harden it.
• The decision states whether any current production workflow depends on command mode.
• Retirement criteria or the least-privilege credential boundary is explicit.
• The decision names the bounded follow-up files and tests.
• No provider command, token, secret value, or external mutation is used to reach the decision.

Tests/Evals

• Read-only workflow and code inspection is sufficient.
• Do not execute AGENTIC_PROVIDER_COMMAND or inspect environment values.

Verification

• Review agentic/contract.json, .github/workflows/agentic-dev-loop.yml, and focused provider-adapter tests.
• Confirm the default remains noop until the decision is implemented.

Agent Instructions

• Do not change files in this issue.
• Do not execute provider-capable commands or dump environment variables.
• Do not infer production use from the mere existence of the optional mode.

Human Checkpoints

• KK must decide retain versus retire.
• Any credential, workflow-permission, or provider change requires a separate implementation PR.

Out of Scope

• Implementing retirement or hardening.
• Selecting a new provider.
• Branch protection, deployment, or credential rotation.
• Reading repository or environment secrets.

Linear

Not applicable. Rafiki delivery is GitHub-only; do not create or update a Linear issue.