D841 — lint folds its output with one digest enum, not three parameters

Decision. The lint tool gains one optional parameter, digest, an enum of by_map (adds counts_by_check_and_map), paths (one check, answers its distinct sorted paths) and compact (each finding as {check, path} only). A limit above the page cap is reported with limit_clamped: true. The default output is unchanged; the modes are read-only and add no lock or commit.

Why. Issue #841 proposed three separate parameters (group_by, distinct, a compact flag). The agent-profile tools/list budget (D285) is shared by every tool, and each top-level parameter costs bytes there for every session whether it uses the feature or not. One enum costs one key and its values; a further mode is a new value, not a new key.

Alternatives rejected. Three parameters: more schema bytes and combinations that must be refused (distinct without a check). omitempty on the shared finding type for the compact form: it would change the full-output contract (message always present, D342); compact uses its own type.

Consequences. by_map counts are built on the unfiltered findings, like counts_by_check, so the rows add up to it whatever check says. A mode that returns a different shape (paths) is a mode, not a flag: a new digest value must say what it answers in docs/control-plane.md §API MCP, and detail stays there, not in the tool description.