Predictive Cost Estimation¶

Before RoboDev launches a task, the cost estimator predicts how much it will cost and how long it will take. This gives operators visibility into expensive tasks before they run — and optionally blocks tasks that exceed a configured threshold until a human approves them.

How It Works¶

Estimation runs in two stages:

1. Complexity Scoring¶

The task is scored across four dimensions, each normalised to [0, 1]:

Dimension	What it measures
`description_complexity`	Length and vocabulary of the ticket description
`task_type_complexity`	Task category — bug fix, refactor, feature, migration, etc.
`repo_size`	Number of files in the repository
`label_complexity`	Labels attached to the ticket

A weighted average produces an overall complexity score. The weights are configurable.

2. k-NN Prediction¶

The overall score and the selected engine are used to query a SQLite store of historical task outcomes. The k=5 nearest neighbours (by complexity score and engine) are retrieved, and P25/P75 percentile ranges are computed for cost and duration:

Predicted cost:     $2.10 – $4.80   (P25–P75)
Predicted duration: 8 – 22 minutes  (P25–P75)
Confidence:         0.8              (based on sample count)

Confidence increases with the number of matching historical outcomes, up to 1.0 at k=5 neighbours. With fewer than 2 neighbours, the predictor falls back to engine-specific cold-start defaults from configuration, with a confidence of 0.1.

Every task outcome — actual cost, actual duration, complexity score, engine used — is fed back into the store after completion, so predictions improve continuously as the system accumulates history.

Auto-Rejection Threshold¶

When max_predicted_cost_per_job is configured, tasks whose predicted cost exceeds the threshold are automatically rejected before a job is created. The controller calls MarkFailed on the ticket, logs a warning, and emits a Prometheus metric. The ticket is not held for human approval — it is failed immediately.

estimator:
  enabled: true
  max_predicted_cost_per_job: 10.00   # USD — auto-reject above this

This is distinct from max_cost_per_job in the guard rails, which is a hard runtime ceiling enforced by the watchdog. The estimator threshold fires before the job starts; the guard rail fires during execution.

Cold-Start Defaults¶

For engines with no historical data, the predictor uses configurable per-engine defaults scaled by complexity:

estimator:
  default_cost_per_engine:
    claude-code:
      low: 1.00
      high: 8.00
    codex:
      low: 0.50
      high: 5.00
  default_duration_per_engine:
    claude-code:
      low_minutes: 5
      high_minutes: 45

Prometheus Metrics¶

Metric	Description
`robodev_estimator_predictions_total`	Total predictions issued
`robodev_estimator_predicted_cost`	Histogram of midpoint predicted costs
`robodev_estimator_auto_rejections_total`	Tasks auto-rejected for exceeding the cost threshold