PHASE 7 FAILURE MODEL — CONTROL PLANE CRASH, ERROR, AND RECOVERY SEMANTICS¶

Project: AeroDB Phase: Phase 7 — Control Plane, Admin UI, and Operator Tooling Status: AUTHORITATIVE · NON-NEGOTIABLE

1. Purpose of This Document¶

This document defines the failure model for Phase 7.

Phase 7 failures are fundamentally different from data-plane failures:

• They MUST NOT affect data correctness
• They MUST NOT alter kernel state implicitly
• They MUST NOT create ambiguity about what has or has not executed

This document ensures that control-plane failure cannot become system failure.

2. Failure Philosophy¶

When the control plane fails, the system must remain unchanged.

Phase 7 failures are handled by:

• Explicit rejection
• Explicit termination
• Explicit operator re-issuance

Phase 7 never attempts to repair, retry, or complete an action after failure.

3. Failure Domains¶

Phase 7 defines the following failure domains:

1. Client-side failures (UI / CLI)
2. Control-plane process failures
3. Network and transport failures
4. Kernel rejection or failure
5. Operator-induced errors

Each domain is handled explicitly and deterministically.

4. Client-Side Failures (UI / CLI)¶

4.1 Crash or Termination Before Request Submission¶

If the UI or CLI crashes before a request is submitted:

• No request reaches the kernel
• No state change occurs
• No audit record of execution is created

Outcome:

• System state is unchanged
• Operator must reissue the request

4.2 Crash After Request Submission, Before Confirmation¶

If a mutating action requires confirmation and the client crashes before confirmation:

• The request MUST NOT be executed
• No kernel action occurs

Outcome:

• Action is discarded
• Operator must restart and reissue

4.3 Client Crash After Confirmation, Before Response¶

If the client crashes after confirmation but before receiving a response:

• The execution outcome MUST be determined from kernel state
• The control plane MUST NOT guess

Rules:

• If kernel state reflects execution → action succeeded
• Otherwise → action did not occur

Client-side uncertainty does not alter system truth.

5. Control-Plane Process Failures¶

5.1 Crash Before Kernel Request Dispatch¶

If the control-plane process crashes before forwarding a request:

• No kernel request occurs
• No state change occurs

Outcome:

• Action did not execute

5.2 Crash During Kernel Request Dispatch¶

If the control-plane process crashes while dispatching a request:

• The request is treated as not executed unless kernel durability proves otherwise

Rules:

• No assumptions are allowed
• Kernel state is authoritative

5.3 Crash After Kernel Acknowledgement¶

If the control-plane process crashes after the kernel acknowledges execution:

• The action is considered executed
• Recovery MUST rely on kernel state only

The control plane does not attempt replay.

6. Network and Transport Failures¶

6.1 Request Transmission Failure¶

If a request fails to reach the kernel:

• The action MUST NOT execute

Outcome:

• Operator must reissue

6.2 Duplicate Requests¶

If duplicate requests are received:

Rules:

• The control plane MUST detect duplicates where possible
• Otherwise, the kernel MUST reject duplicates deterministically

Silent duplicate execution is forbidden.

7. Kernel Rejection and Failure¶

7.1 Kernel Rejection¶

If the kernel rejects a request:

• The rejection MUST be surfaced verbatim
• The control plane MUST NOT reinterpret or retry

Kernel rejection is final.

7.2 Kernel Failure¶

If the kernel fails (crash, fatal error) during request handling:

• The control plane MUST treat the request as not executed unless kernel durability proves otherwise

Operator must investigate kernel state explicitly.

8. Operator-Induced Errors¶

8.1 Invalid Requests¶

If an operator issues an invalid request:

• The request is rejected
• The rejection must include explanation

No attempt is made to auto-correct input.

8.2 Abandoned Operations¶

If an operator abandons an operation mid-flow:

• No partial execution may occur
• No cleanup action is triggered automatically

The system remains unchanged.

9. Failure Visibility and Audit¶

All failures MUST:

• Be observable
• Be logged
• Be explainable

Audit records MUST include:

• Failure type
• Time
• Affected request
• Outcome (executed / not executed)

10. Recovery Rules¶

Phase 7 recovery is trivial by design.

Rules:

• No in-flight state is recovered
• No partial execution is completed
• No retries are attempted

Recovery means restart and resume observation only.

11. Explicit Non-Recovery¶

Phase 7 MUST NOT:

• Attempt rollback
• Attempt roll-forward
• Attempt reconciliation

Those concepts belong to the kernel only.

12. Testing Requirements¶

Phase 7 failure handling MUST be tested for:

• Client crash scenarios
• Control-plane crash scenarios
• Network failure scenarios
• Kernel rejection propagation

Tests MUST assert:

• No partial execution
• No hidden retries
• Deterministic outcomes

13. Final Statement¶

Phase 7 failure handling exists to protect correctness by doing nothing.

It prefers:

• Rejection over uncertainty
• Restart over repair
• Human re-issuance over automation

If the control plane fails, the safest action is inaction.

This failure model is absolute.

END OF PHASE 7 FAILURE MODEL