====== P4-REQ-21-11-007 ======

[[dido:99_annexes:annex-d-requirements:part-04:start| Return to Requirements]]

===== Statement =====

The Developer Handbook SHALL define exception-handling patterns.

===== Source =====

Part 4, Section 21.11: Developer Handbook Requirements.

===== Rationale =====

Exception-handling patterns ensure that implementation failures are handled or reported consistently rather than being silently hidden.

Defined patterns support operational condition reporting, processing accountability, recovery coordination, audit and provenance, and later evidence planning.

===== Applies To =====

This requirement applies to:

  * hand-authored implementation code;
  * implementation node artifacts;
  * supporting modules;
  * scripts where applicable; and
  * logging, status, control, and audit mechanisms.

===== Verification =====

Verification SHALL confirm that the Developer Handbook defines exception-handling patterns.

Verification activities should include review checks confirming that:

  * exception context requirements are defined;
  * processing outcomes are addressed;
  * retry or recovery expectations are addressed;
  * logging and status effects are addressed; and
  * applicable Audit and Provenance or Control Plane effects are addressed.

===== Traceability =====

This requirement establishes the exception-handling discipline applied across Phase 0 implementation artifacts and interaction realizations.

Related requirement identifiers:

  * [[dido:99_annexes:annex-d-requirements:part-04:p4-req-21-11-006]]
  * [[dido:99_annexes:annex-d-requirements:part-04:p4-req-21-8-008]]

Related source section:

  * [[fxdemo:04-part:21-phase-0-implementation-requirements:21-11-developer-handbook-requirements:start]]

===== Status =====

Draft

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