Module rules_overhead 

Shared accounting for the rules files an agent auto-loads each session.

A “rules file” (CLAUDE.md, AGENTS.md, .cursor/rules/*.mdc, …) is injected into every session as fixed context — it costs tokens before lean-ctx saves anything. This module enumerates those files, attributes the lean-ctx-owned share of each, and flags clients that load the same guidance more than once.

Used by lean-ctx doctor overhead (fixed-cost board) and lean-ctx tools health (token-budget / rot report, #848). Lives in core so neither caller has to depend on the other.

Structs

DuplicateChannel

One host whose session receives lean-ctx rules (the tool mapping) through more than one channel (A3: exactly one channel per host).

RulesFileCost

One rules file a client auto-loads into context.

Functions

collect_rules_files

Collects every rules file that an agent auto-loads for work in project: global per-client files, the project root, and the parent chain up to home (Cursor merges parent .cursor/rules/ and AGENTS.md in monorepos).

duplicate_channels

Hosts that load the lean-ctx rules block more than once per session: several auto-loaded files carrying it, or one such file plus the full MCP instructions skeleton (the server only collapses it to the anchor when the host’s canonical carrier holds the block, rules_channel::client_autoloads_rules). instruction_tokens_for prices the skeleton a client receives (doctor passes the live builder).

duplicate_clients

Clients that auto-load more than one file carrying a full lean-ctx payload — the same guidance billed multiple times per session (#578/#684).