wayfinder-router 0.1.0

A deterministic prompt-complexity router: score a prompt's structure and recommend a local or cloud model — offline, reproducible, no model call.

A deterministic prompt-complexity router. Hand it a prompt, get back a reproducible structural complexity score and a recommendation:

route this prompt to your local model, or to the cloud model?

It is a standalone tool. It calls no model, needs no API key, makes no network request, and has zero dependency on RAC — it is pure text scanning plus a threshold. The recommendation is a fact you act on; Wayfinder stops there, and the caller runs inference.

Quickstart (gateway)

Put Wayfinder in front of your models — your app keeps using the OpenAI API, you just change base_url. Pilot-facing one-pager: EXPLAINER.md.

1. Describe your two models in wayfinder-router.toml:

   [routing]
   threshold = 0.5            # below -> local, at/above -> cloud
   
   [gateway.models.local]
   base_url = "http://localhost:11434/v1"
   model = "llama3.2"
   
   [gateway.models.cloud]
   base_url = "https://api.openai.com/v1"
   model = "gpt-4o"
   api_key_env = "OPENAI_API_KEY"   # key read from this env var, never stored
   

2. Run the gateway:

   pip install -e ".[gateway]"
   export OPENAI_API_KEY=sk-...
   wayfinder-router serve --port 8088
   

3. Point your existing client at it — no code change:

   client = openai.OpenAI(base_url="http://localhost:8088/v1", api_key="unused")
   client.chat.completions.create(model="auto", messages=[{"role": "user", "content": "..."}])
   

Easy prompts go to local, hard ones to cloud; each response carries x-wayfinder-router-model and x-wayfinder-router-score so you can see the routing.

Check it's working (the headers show where each request went):

curl -s localhost:8088/healthz                         # {"status":"ok","models":["cloud","local"]}
curl -s -D - -o /dev/null http://localhost:8088/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{"model":"auto","messages":[{"role":"user","content":"hi"}]}' \
  | grep -i x-wayfinder-router
# x-wayfinder-router-model: local
# x-wayfinder-router-score: 0.00

Why deterministic

The obvious way to route by complexity is to ask a model how complex the prompt is — an LLM-as-judge router. That is non-deterministic, costs a model call to decide whether to make a model call, and cannot be reproduced or tested. Wayfinder takes the opposite stance: it scores structure — length, headings, instruction steps, links, code blocks, tables — combines the signals into a bounded 0.0–1.0 score, and compares that to a threshold you control. Same prompt and same threshold always give the same answer.

The score is a structural proxy, not a verdict on difficulty: whether it tracks "this prompt needs the cloud model" is your calibration, which is exactly why the threshold is yours to set.

Run it (offline, no install)

cd wayfinder-router
echo "Summarise this paragraph in one sentence." | python -m wayfinder_router.cli route -
make route PROMPT=path/to/prompt.md

Recommended Model: local
Complexity Score: 0.00  (mode: tiered)

Tiers:
  >= 0.00  local <-
  >= 0.50  cloud

Contributing Features:
  Word Count: 6
  ...

JSON for machine consumers (an agent reads this and routes to its own model):

wayfinder-router route prompt.md --json

{
  "schema_version": "2",
  "score": 0.66,
  "recommendation": "cloud",
  "mode": "tiered",
  "features": { "word_count": 545, "heading_count": 12, "...": 0 },
  "tiers": [{ "min_score": 0.0, "model": "local" }, { "min_score": 0.5, "model": "cloud" }]
}

Install

pip install -e .              # the `wayfinder-router` command on PATH (zero dependencies)
pip install -e ".[gateway]"   # plus the OpenAI-compatible routing gateway
pip install -e ".[ui]"        # plus the local calibration/explain/configure UI
pip install -e ".[dev]"       # plus the test runner

Configure routing

Wayfinder reads its own config — never RAC's .rac/. Drop a wayfinder-router.toml anywhere at or above where you run it. Three modes, in precedence order (classifier > tiers > threshold); weights (the scalar-score weights) apply to any of them.

Binary (the default) — one cut:

[routing]
threshold = 0.6
weights = { word_count = 4.0, list_item_count = 2.5 }

--threshold N overrides it for one run; WAYFINDER_ROUTER_THRESHOLD overrides via the environment.

Tiered (WF-ADR-0002) — ordered score bands route to any number of models:

[[routing.tiers]]
min_score = 0.0
model = "llama-3b"
[[routing.tiers]]
min_score = 0.3
model = "llama-70b"
[[routing.tiers]]
min_score = 0.6
model = "claude-cloud"

Classifier (WF-ADR-0003) — a fitted multinomial-logistic model; argmax over per-model linear scores. Usually produced by calibrate, not hand-written.

Calibrate from data

The cut is a proxy; calibrate it against your traffic. wayfinder-router calibrate reads a labeled JSONL dataset ({"text": ..., "label": ...}) and emits a config fragment — offline, deterministic, and it never calls a model (labels come from your own oracle):

wayfinder-router calibrate data.jsonl --mode threshold              # sweep the binary cut
wayfinder-router calibrate data.jsonl --mode tiers                  # ordinal multi-model
wayfinder-router calibrate data.jsonl --mode classifier --out wayfinder-router.toml

The emitted fragment drops straight into wayfinder-router.toml; the summary (accuracy, chosen breakpoints) is printed to stderr. The classifier is fit by deterministic L2-regularized Newton/IRLS — pure Python, converging in a handful of iterations.

Route with your own key (gateway)

To actually route — score the prompt, then call the chosen model with your own key — run the OpenAI-compatible gateway (WF-ADR-0004). Your existing client points its base_url at Wayfinder; no application code changes.

# wayfinder-router.toml — map each routed model name to an upstream + a key env var.
[routing]
threshold = 0.6

[gateway.models.local]
base_url = "http://localhost:11434/v1"
model = "llama3.2"

[gateway.models.cloud]
base_url = "https://api.example.com/v1"
model = "big-model"
api_key_env = "EXAMPLE_API_KEY"   # the *name* of the env var; the secret is never in this file

pip install -e ".[gateway]"
export EXAMPLE_API_KEY=...     # read at request time, only inside the gateway
wayfinder-router serve --port 8088

import openai
client = openai.OpenAI(base_url="http://localhost:8088/v1", api_key="unused")
client.chat.completions.create(model="auto", messages=[{"role": "user", "content": "..."}])
# Wayfinder scores the prompt, forwards to local or cloud, and returns the response.
# Response headers carry x-wayfinder-router-model and x-wayfinder-router-score.

The gateway is the only part that touches keys or the network; the scorer, config, and calibrator stay pure, offline, and deterministic. Keys are read from the environment at request time and never enter wayfinder-router.toml or the scored path.

Learn from feedback (onboarding)

Don't guess the cut — learn it from your own judgment of local vs hosted output (WF-ADR-0006). The loop is: collect judgments → calibrate → route automatically.

Bootstrap with A/B onboarding. For each sample prompt, wayfinder-router onboard runs both arms and asks which was good enough; the answer is a label:

wayfinder-router onboard prompts.jsonl --arms local,cloud --calibrate > wayfinder-router.toml

The A/B comparison and the prompt go to stderr; --calibrate prints the resulting config to stdout. Each judgment appends a {"text", "label"} line to a feedback log — which is the calibrate dataset, so the log turns straight into a config.

Keep it honest with steady-state feedback. Once routing automatically, record which model was actually good enough; the label feeds the next recalibration:

curl localhost:8088/v1/feedback -d '{"text": "...", "label": "cloud"}'

Recalibrate on a schedule (WF-ADR-0007). Re-fit the routing config from the log — run it from cron / a k8s CronJob, or click "Recalibrate & save" in the UI's Onboard tab. It rewrites only the [routing] section and preserves your [gateway] endpoints; a running gateway hot-reloads the new config with no restart:

wayfinder-router recalibrate                  # log → calibrate → write wayfinder-router.toml
wayfinder-router recalibrate --min-labels 50  # no-op until you have enough signal

The judging runs models, so it lives in the gateway/invocation layer (BYO key); the deterministic core is untouched and the label log carries no secrets.

Deploy & integrate (WF-ADR-0008)

Wayfinder doesn't only work from the CLI — the CLI, onboarding, and UI are the operator/bootstrap surfaces. In production, prompts flow through the gateway (transparent) or the library (in-process); routing happens where prompts already are, not by re-typing them.

Run the gateway as a service (sidecar or standalone):

docker build -t wayfinder-router . && docker run -p 8088:8088 -v "$PWD/data:/data" wayfinder-router
# or: docker compose up gateway   (see docker-compose.example.yml)

Point your existing client at it — no app code change. Anything that speaks the OpenAI API takes a base_url:

client = openai.OpenAI(base_url="http://localhost:8088/v1", api_key="unused")

The same base_url works for agent frameworks (LangChain/LlamaIndex), IDE assistants that allow a custom endpoint (Cursor, Continue), or a gateway like LiteLLM. Wayfinder scores each incoming prompt and forwards to the chosen model with your key.

Wire feedback from the host surface. Your app/IDE/chat decides how to show a 👍/👎 and posts the judgment; Wayfinder records it and the next recalibration learns from it:

fetch("http://localhost:8088/v1/feedback", {
  method: "POST",
  body: JSON.stringify({ text: prompt, label: wasGoodEnough ? "local" : "cloud" }),
});

Schedule recalibration with cron / a k8s CronJob (or docker compose run --rm recalibrate); the gateway hot-reloads the result. Keys always come from the environment (each model's api_key_env) — never the image or the config file.

Explain & tune

To see why a prompt routed where, ask for the per-feature breakdown — each feature's value, its normalized level, its weight, and its share of the score:

wayfinder-router route prompt.md --explain

For interactive tuning there's a local web UI (WF-ADR-0005) with three tabs:

• Explain — paste a prompt; see the score, tier ladder, and contribution bars, and drag a threshold slider to watch routing change live.
• Calibrate — paste a labeled JSONL dataset; run a mode; see accuracy, the threshold-sweep curve, and the resulting config fragment, then send it to Configure.
• Configure — edit wayfinder-router.toml with live validation (the real loaders) and save.
• Onboard — A/B a local vs hosted model on sample prompts in the browser, judge each, record labels, then calibrate from the log (needs [gateway] too, for the model calls).

pip install -e ".[ui]"
wayfinder-router ui --port 8099    # then open http://localhost:8099

The UI is a thin consumer of the same pure functions; it never calls a model, and no secret ever appears in it (a gateway model names an api_key_env; the key lives in the environment).

Python API

from wayfinder_router import score_complexity, RoutingConfig, explain_score

result = score_complexity(prompt_text, config=RoutingConfig.binary(threshold=0.7))
print(result.recommendation, result.score, result.features)
for fc in explain_score(result.features, RoutingConfig().weights):
    print(fc.name, fc.contribution)

Heritage

Wayfinder began as the rac route exploration inside requirements-as-code, and its scoring shape is inspired by RAC's deterministic classification.py (points / ceiling). It was split out because routing is a runtime inference concern, divergent from RAC/Lore's recorded-knowledge product line — a prompt router should not require installing a requirements-as-code engine. The shipped tool shares no runtime code with RAC; see decisions/WF-ADR-0001.

Repository layout

wayfinder-router/
  wayfinder_router/     the package: complexity scorer, tiers + classifier, own config
                 loader + writer, offline calibration (Newton/IRLS), explain, the
                 feedback log + onboarding harness, recalibration, CLI, and the
                 optional OpenAI-compatible gateway and local UI (impure layers,
                 behind their extras)
  tests/         scorer, config, calibration, explain, feedback, onboard,
                 recalibrate, CLI, gateway, and UI coverage
  decisions/     ADRs grounding the tool's own choices (dogfooded)
  Dockerfile, docker-compose.example.yml   deploy the gateway as a service

Test

pip install -e .[dev]   # or: pip install pytest
make test