# Sprint 64 Plan: Cost-Aware Transpilation Planning

## Context

As pair matrix grows, planning compute and human-review cost becomes essential.
Sprint 64 adds cost-aware planning before execution.

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## Goals

1. Estimate cost for transpilation plans (compute, review, time)
2. Offer plan alternatives by cost/risk profile
3. Improve scheduling for high-value pair upgrades
4. Enforce budget policies in orchestrated runs

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## Steps

### Step 869: Porting cost model v1 (12 tests)
### Step 870: Review effort estimator from ambiguity/risk packets (10 tests)
### Step 871: Compute/runtime cost estimator from prior runs (10 tests)
### Step 872: Multi-plan alternative generator (`cheap`, `balanced`, `rigorous`) (10 tests)
### Step 873: Budget policy enforcer integration (10 tests)
### Step 874: Cost-vs-quality tradeoff report generator (8 tests)
### Step 875: `whetstone_plan_transpilation_run` MCP tool (8 tests)
### Step 876: `whetstone_estimate_porting_cost` MCP tool (8 tests)
### Step 877: Cost telemetry integration in metrics stack (8 tests)
### Step 878: Sprint 64 integration summary + regression (8 tests)

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## Policy Rule

- Over-budget plans require explicit reviewer approval token.