# Sprint 126 Plan: Campaign Checkpointing, Resume, and Export

## Context

Sprint 125 added deterministic multi-target debug campaigns and safety envelopes.
Sprint 126 adds checkpoint capture, deterministic resume planning, and export bundles
so agents can pause/recover work and produce machine-readable artifacts.

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## Goals

1. Add campaign checkpoint models and deterministic storage
2. Add deterministic queue/resume planning utilities
3. Add MCP tools for checkpoint save/list/resume and export
4. Preserve deterministic ordering and replayability

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## Steps

### Step 1499: Campaign checkpoint model (10 tests)
### Step 1500: Campaign checkpoint store (10 tests)
### Step 1501: Campaign queue policy model (10 tests)
### Step 1502: Campaign resume planner model (8 tests)
### Step 1503: `whetstone_save_campaign_checkpoint` MCP tool (8 tests)
### Step 1504: `whetstone_list_campaign_checkpoints` MCP tool (8 tests)
### Step 1505: `whetstone_resume_debug_campaign` MCP tool (8 tests)
### Step 1506: Campaign export bundle model (8 tests)
### Step 1507: `whetstone_export_debug_campaign_bundle` MCP tool (8 tests)
### Step 1508: Sprint 126 integration summary + regression (8 tests)

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## Architecture Gate

- Checkpoint ordering must be deterministic and stable
- Resume must use latest checkpoint by deterministic rule
- Export bundles must be machine-readable and replay-friendly
- Max 600 lines per header