Deliverables

flowchart LR
  crm["CRM"]
  oms["Order Mgmt"]
  erp["ERP"]
  wms["WMS"]
  bill["Billing<br/><i>mainframe</i>"]
  dw[("Warehouse")]
  ptnr["Partner"]

  crm -->|"I-01 · REST · on demand"| oms
  oms -->|"I-02 · SFTP CSV · nightly"| erp
  oms -->|"I-03 · MQ · near real time"| wms
  wms -->|"I-04 · REST · on demand"| oms
  erp -->|"I-05 · flat file · nightly"| bill
  bill -->|"I-06 · DB link · nightly"| dw
  oms -->|"I-07 · CDC · continuous"| dw
  ptnr -->|"I-08 · AS2 EDI · hourly"| oms
  oms -->|"I-09 · AS2 EDI · hourly"| ptnr

flowchart TB
  t1["T-7d · Dry run in staging<br/><i>full rehearsal, timed</i><br/>owner: Delivery"]
  t2["T-1d · Freeze changes · verify backups<br/>confirm rota and bridge<br/>owner: Ops"]
  t3["T-0 00:00 · Enable read-only on legacy<br/>owner: Ops"]
  t4["T-0 00:15 · Final delta migration<br/><i>est 90 min · checkpoint at 60</i><br/>owner: Data"]
  t5["T-0 01:45 · Reconcile counts + checksums<br/>owner: Data"]
  g1{"T-0 02:15 · GO / NO-GO<br/><i>criteria: 100% row match,<br/>0 critical defects, all owners present</i>"}
  t6["T-0 02:30 · Repoint DNS + feature flag<br/><i>TTL pre-lowered to 60s</i><br/>owner: Platform"]
  t7["T-0 02:45 · Smoke suite + 10 manual journeys<br/>owner: QA"]
  g2{"T-0 03:30 · Accept or roll back"}
  t8["T-0 03:30 · Open to 10% traffic<br/>owner: Platform"]
  t9["T-0 06:00 · 100% traffic<br/>owner: Platform"]
  t10["T+24h · Hypercare ends<br/>legacy kept read-only 30d"]
  rb(["ROLLBACK · revert DNS<br/>re-enable legacy writes<br/><i>est 20 min</i>"])
  pnr["POINT OF NO RETURN<br/><i>after first write to new system<br/>rollback needs reverse migration</i>"]

  t1 --> t2 --> t3 --> t4 --> t5 --> g1
  g1 -->|"no-go"| rb
  g1 -->|"go"| t6 --> t7 --> g2
  g2 -->|"roll back"| rb
  g2 -->|"accept"| t8 --> t9 --> t10
  t8 -.-> pnr

flowchart LR
  subgraph w0["Wave 0 — Foundation"]
    direction TB
    f1["Landing zone"]
    f2["Connectivity + DNS"]
    f3["Identity federation"]
    f4["Observability + backup"]
  end

  subgraph w1["Wave 1 — Prove it (6 apps)"]
    direction TB
    a1["Internal wiki<br/><i>rehost</i>"]
    a2["Reporting portal<br/><i>rehost</i>"]
    a3["Batch scheduler<br/><i>replatform</i>"]
  end

  subgraph w2["Wave 2 — Bulk (34 apps)"]
    direction TB
    b1["Departmental apps<br/><i>rehost ×26</i>"]
    b2["Shared services<br/><i>replatform ×8</i>"]
  end

  subgraph w3["Wave 3 — Hard cases (9 apps)"]
    direction TB
    c1["Order management<br/><i>refactor</i>"]
    c2["Data warehouse<br/><i>replatform</i>"]
    c3["Partner gateway<br/><i>refactor</i>"]
  end

  subgraph w4["Wave 4 — Exit"]
    direction TB
    d1["Mainframe interfaces<br/><i>replace</i>"]
    d2["Data centre exit<br/><i>contract ends Q3</i>"]
  end

  w0 -->|"platform accepted<br/>by security + ops"| w1
  w1 -->|"runbook proven<br/>rollback rehearsed"| w2
  w2 -->|"shared services live<br/>latency measured"| w3
  w3 -->|"last dependency<br/>severed"| w4