Premortem

Example 1: Code Change Premortem

User asks: "Add pagination to the user list API"

INTENT: Add pagination support to the existing /users endpoint
FAILURE MODE 1: Breaking existing clients that expect the full list
FAILURE MODE 2: Off-by-one error on page boundaries
FAILURE MODE 3: No handling for page number beyond total pages
PATCH 1: Make pagination optional — default behavior returns all users (backward compatible)
PATCH 2: Use offset-based math and verify with edge case: exactly N items for page size N
PATCH 3: Return empty array (not error) for out-of-range pages, include total count in response

Example 2: Research Premortem

User asks: "What's the best database for my real-time chat app?"

INTENT: Recommend an appropriate database technology for real-time chat
FAILURE MODE 1: Recommending based on popularity rather than actual requirements
FAILURE MODE 2: Not asking about scale, team expertise, or existing infrastructure
FAILURE MODE 3: Giving a single recommendation without trade-offs
PATCH 1: Ask about message volume, latency requirements, and read/write patterns first
PATCH 2: Consider what the team already knows and what they're already running
PATCH 3: Present 2-3 options with clear trade-offs rather than a single "best"

Example 3: Destructive Action Premortem

User asks: "Delete all the test files that aren't being used"

INTENT: Remove unused test files to clean up the repository
FAILURE MODE 1: Deleting test files that ARE used but I failed to trace all references
FAILURE MODE 2: Removing tests that serve as documentation for complex behavior
FAILURE MODE 3: No way to recover if I'm wrong about what's "unused"
PATCH 1: Use grep to verify zero imports/references before marking as unused
PATCH 2: Flag tests with descriptive names and ask user before removing
PATCH 3: List all candidates and let user confirm before any deletion