tau(x) -> lane_i(endpoint_i)delta = turn_n - cached_prefixcache(prefix) == byte-identicaldiag(t) + edit(t)[ 00 01 10 11 ]x / 128y / 064
Why Tau?
01Tools in every mode
Both /mode cheap and /mode normal include the same standard Tau tools by default: file operations, shell execution, search, and the core agent workflow. Cheap mode keeps that working set without loading extra capability surfaces. Normal mode can add the optional layer through /tools: workflow detection, test pairing, package safety, integration and deploy checks, browser inspection, visual audits, artifacts, diffs, diagrams, AFT, and LSP. It can also load subagents, skills, MCP servers, and plugins when the project needs them.
/tools by task02Provider-native lanes
Tau does not force every model through one generic server. Each provider has a lane that normalizes messages, requests, and responses into the endpoint shape that provider expects, so Anthropic, OpenAI-compatible, Antigravity, Cline, Kiro, local, and gateway models keep their native protocol instead of a flattened imitation.
distributed lanes03Context optimization
Tau treats cache hit rate as a design target. Stable system and tool bytes stay in the cacheable prefix, volatile session context stays after the dynamic boundary, provider lane affinity keeps repeated requests routed consistently, and each lane protects the byte identity needed for cache hits.
cache hit rate04Diagnostics during edits
Optional LSP tools give Tau definitions, references, hover text, symbols, call hierarchy, and diagnostics while code is still active. A broken reference can be caught in the same run instead of after the useful context has already moved on.
optional LSP05Signals from long logs
Lint and exception output can be huge. Tau prunes around the useful signals: the important error, the top and tail, and the nearby lines needed to act. The agent reads the failure, not a wall of repeated log noise.
log pruning06Snapshots and session control
Tau keeps session state project-local. Resume and branch trees carry the run state, while snapshots save working-tree checkpoints into a shadow git store separate from the real .git. Save, list, diff, and restore give time travel without rewriting project history.
sessions / snapshots07Self-learning loop
After meaningful work, /learned can propose one reusable lesson. Approve, edit, or skip it; approved lessons land in project memory with origin: learned, then can be viewed, edited, deleted, or turned off from the same hub.
/learned memory08Claude Code compatible extensions
Tau can load MCP servers, LSP integrations, agents, plugins, and skills shaped for Claude Code. Keep them off in cheap mode, or expose them in normal mode when a project benefits from that surface.
MCP / LSP / agents 
