# Faithful R2 lean-ctx arm — engine config (config.toml).
#
# Copy to the lean-ctx config dir ($XDG_CONFIG_HOME/lean-ctx/config.toml) or drop
# into the repo workspace as `.lean-ctx.toml` (project-local override). Every key
# below is a real engine setting — no env var is required for these to take effect,
# though each also has a LEAN_CTX_* override (see faithful-arm.env).
#
# Goal: neutralize the R1 +38% injected-prefix tax and keep cold reads
# capability-safe-cheap on a phase-isolated harness.

# Zero-injection: do not inject rule files into the agent's context. The R1 tax
# was a ~3K-token per-turn prefix (rule file + tool schemas) re-billed every turn
# on a non-caching rail. "off" removes the rule-file half entirely.
rules_injection = "off"

# Minimal overhead: trims the per-tool schema/preamble surface so the fixed
# injected cost per turn is as small as possible.
minimal_overhead = true

# Minimal tool profile: expose the 6-tool core instead of the full ~15 ctx_*
# surface, shrinking the other half of the injected prefix (the tool schemas).
tool_profile = "minimal"

# Structure-first cold reads: on a fresh process (no warm session cache to
# amortize a full read) bias `auto` toward `map` for medium source files. This
# is the only read saving that survives phase isolation, and it aids
# localization (deps + located API + task-relevant body). All capability guards
# stay in force: active_diagnostic / edit-fail / small-file / task-named files
# are always read full.
structure_first = true

# Proxy: the cross-tool wire compressor. The only path that reaches another
# tool's output (e.g. forge_* store reads) and native shell/build/test logs, so
# "installed = compressing the whole addressable surface", not just ctx_* tools.
proxy_enabled = true
proxy_port = 4444

[proxy]
# cache-aware history pruning keeps the request prefix byte-stable so a
# cache-priced rail (Anthropic) keeps hitting the prompt cache (#498). Never use
# "rolling" on a cached rail — it rewrites a stable message every turn and turns
# cheap cache reads into full-price writes.
history_mode = "cache-aware"