Work Plan — branch-scoped working memory

One line: the branch is the unit of work; one committed plan per branch is its memory. Plans hold volatile state (what we're doing, where we stopped). Durable truth — specs, glossary, decisions — lives in _docs/ and is owned by rjv-spec-driven. The plan links to durable docs, never duplicates them.

• .plans/<name>.md = working memory for ONE branch (one plan per branch). Committed, so any agent on any machine that checks out the branch resumes from it.
• Each plan declares Branch: <name> in its header. The file itself can be named anything readable (a topic name is fine); the current branch is the key, and resume finds the plan whose Branch: matches git branch --show-current. No index to maintain — git branches ARE the active-work index, and the branch you have checked out is which plan, without being told.
• A plan is never deleted. It ships with the code: on merge it moves to .plans/shipped/ with a final status and dates. .plans/*.md (top level) = work in flight; .plans/shipped/ = the delivery record. The lifecycle runs past merge into maintenance — see LIFECYCLE.md.