Agents that must edit files beyond a task's declared ## File Scope had no
way to keep the scope in sync, so those edits were stranded at merge (the
squash merge is scoped to ## File Scope, and cross-task overlap blocking +
the merge file-scope invariant both read it).
New executor tool fn_task_file_scope_add validates repo-relative
paths/globs with isValidFileScopeEntry, de-dupes against existing scope,
appends them to the ## File Scope section of PROMPT.md, and persists via
store.updateTask({ prompt }) (same validation + task.json/PROMPT.md sync as
fn_task_prompt_write). Registered in the main coding-agent tool list; the
base executor prompt now instructs the agent to call it when editing beyond
the declared scope. Merge-time peer-claim refusal is unchanged and remains
the cross-task backstop.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
f10c39fa0b