A Hunk Map for a Ninety-Minute Spike

Description and use

A hunk map tracks changes in a 90‑minute spike, ensuring only hypothesis‑related edits are merged.

Problem

Time‑boxed agent work often leaves untracked, unrelated edits that slip into the main branch, making review and merge risky.

Outcome

The hunk map enforces that only changes directly tied to the hypothesis are merged, preventing accidental code drift during time‑boxed spikes.

Workflow

• Freeze baseline commit and create .spike/hypothesis.txt and .spike/hunk-map.yml
• Run the spike in a dedicated worktree
• After each agent turn, run host‑side checker to parse git diff
• Checker matches each hunk header to the map and verifies tags
• If any hunk is unlisted or tag mismatches, the spike is killed
• Otherwise continue until deadline or all hunks are accepted

Evidence

The host will append tags only after reading a real diff, never in advance of the change.

Source

A small checker then becomes the ship‑or‑kill gate for the rest of the ninety minutes.

Source