Deliverables

gantt
  title Target state — 18 months
  dateFormat YYYY-MM-DD
  axisFormat %b %y

  section Foundation
  Landing zone and connectivity      :done,   f1, 2026-01-01, 60d
  Identity federation                :done,   f2, after f1, 45d
  Observability baseline             :active, f3, after f1, 75d

  section Decouple
  Strangler facade at edge           :active, d1, 2026-03-15, 90d
  Extract order domain               :        d2, after d1, 120d
  Extract pricing domain             :        d3, after d2, 90d
  Retire shared order database       :crit,   d4, after d3, 60d

  section Data
  Ingest to raw zone                 :        a1, 2026-04-01, 75d
  Conformed customer entity          :        a2, after a1, 90d
  Retire nightly extract jobs        :        a3, after a2, 45d

  section Resilience
  Multi-zone for tier 0              :        r1, 2026-06-01, 60d
  Automated failover rehearsal       :        r2, after r1, 45d
  Second region for tier 0           :crit,   r3, after r2, 90d

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

flowchart TB
  subgraph l1["Capabilities delivered"]
    direction LR
    c1["Product<br/>engineering"] --- c2["Data &<br/>analytics"] --- c3["Platform &<br/>infrastructure"] --- c4["Security &<br/>risk"]
  end
  subgraph l2["Organisation"]
    direction LR
    o1["Stream-aligned teams<br/><i>×9 · own build and run</i>"] --- o2["Platform team<br/><i>×1 · paved road</i>"] --- o3["Enabling team<br/><i>×1 · coaching</i>"] --- o4["Architecture chapter<br/><i>federated</i>"]
  end
  subgraph l3["Ways of working"]
    direction LR
    p1["Product-funded<br/><i>not project</i>"] --- p2["You build it<br/>you run it"] --- p3["Continuous<br/>delivery"] --- p4["Design authority<br/><i>advisory + gates</i>"]
  end
  subgraph l4["Governance"]
    direction LR
    g1["ARB<br/><i>off-radar only</i>"] --- g2["Tech radar<br/><i>quarterly</i>"] --- g3["Automated<br/>compliance"] --- g4["Exception<br/>register"]
  end
  subgraph l5["People"]
    direction LR
    s1["Skills gaps<br/><i>SRE ×6 · data eng ×4</i>"] --- s2["Sourcing<br/><i>hire 6 · reskill 4</i>"] --- s3["Career paths<br/><i>IC track added</i>"]
  end
  l1 --> l2 --> l3 --> l4 --> l5