Error Page And Fallback Planner

error-page-and-fallback-planner

Purpose

Plan user-visible recovery behavior for invalid input, unauthorized access, not found, server failure, and degraded capability cases.

Expected inputs

• feature scope
• existing routes or pages
• data inputs/outputs
• constraints or stack context

Deliverables

• structured recommendation
• design notes
• risks or gaps
• recommended next artifact

Trigger this skill when

• You are designing or reviewing a web feature rather than a generic backend-only function.
• Request flow, form handling, rendering, state, or navigation decisions materially affect correctness.
• A feature needs clearer boundaries between route handling, server logic, and presentation.

Operating procedure

1. Clarify the feature, request path, actors, and current or intended flow.
2. Separate facts, assumptions, constraints, and unresolved web-specific risks.
3. Prefer concrete request/response behavior over abstract framework talk.
4. Explicitly handle invalid, missing, unauthorized, and degraded states where relevant.
5. Recommend the next most useful web engineering or testing skill.

Quality gates

• The recommendation respects actual web request boundaries and browser behavior.
• Missing and invalid states are not ignored.
• Assumptions and unresolved decisions are visible.
• Output is specific enough to influence implementation or testing.

Output style

• Be concrete and structured.
• Separate findings, assumptions, and recommendations.
• Prefer explicit tradeoffs over single-answer absolutism.
• Use severity or priority where useful.

Failure modes to avoid

• Do not rely on client-side behavior as the only safeguard.
• Do not blur controller, rendering, validation, and persistence responsibilities.
• Do not describe happy-path behavior only.
• Do not hide uncertainty behind framework-specific jargon.

Minimum output skeleton

## Summary
## Findings or proposal
## Evidence vs assumptions
## Risks or tradeoffs
## Recommended next skill

Handoff targets

• server-side-validation-enforcer
• presentation-model-designer
• progressive-enhancement-reviewer