samples: FactoryDemo.Api.FSharp — JSON API (v0, in-memory, stack-independent)

Zeta.sln

@@ -20,6 +20,8 @@ Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "Bayesian.Tests", "tests\Bay
 EndProject
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 EndProject
+Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "FactoryDemo.Api.FSharp", "samples\FactoryDemo.Api.FSharp\FactoryDemo.Api.FSharp.fsproj", "{40534D09-439E-4E5F-9A69-A73844DB674D}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -66,5 +68,9 @@ Global
 		{AAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{AAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{AAAAAAAA-AAAA-AAAA-AAAA-AAAAAAAAAAAA}.Release|Any CPU.Build.0 = Release|Any CPU
+		{40534D09-439E-4E5F-9A69-A73844DB674D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{40534D09-439E-4E5F-9A69-A73844DB674D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{40534D09-439E-4E5F-9A69-A73844DB674D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{40534D09-439E-4E5F-9A69-A73844DB674D}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

samples/FactoryDemo.Api.FSharp/FactoryDemo.Api.FSharp.fsproj

@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <RootNamespace>Zeta.Samples.FactoryDemo.Api</RootNamespace>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="Seed.fs" />
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="FSharp.Core" />
+  </ItemGroup>
+</Project>

samples/FactoryDemo.Api.FSharp/Program.fs

@@ -0,0 +1,90 @@
+module Zeta.Samples.FactoryDemo.Api.Program
+
+open System
+open Microsoft.AspNetCore.Builder
+open Microsoft.AspNetCore.Http
+open Microsoft.Extensions.DependencyInjection
+
+// Minimal F# ASP.NET Core Web API serving the seed data for the
+// factory-demo. Stack-independent — any frontend choice (Blazor /
+// React / Vue / Svelte / curl) consumes the same JSON.
+//
+// V0 scope: in-memory seed only, no DB wiring. A Postgres backing
+// with schema.sql + seed-data.sql is a planned follow-up PR; until
+// then this API carries its own in-memory seed so the sample runs
+// with zero external dependencies.
+
+let private pipelineFunnel () =
+    Seed.opportunities
+    |> List.groupBy (fun o -> o.Stage)
+    |> List.map (fun (stage, opps) ->
+        {| Stage = stage
+           Count = opps |> List.length
+           TotalCents = opps |> List.sumBy (fun o -> o.AmountCents) |})
+
+let private duplicateEmails () =
+    Seed.customers
+    |> List.groupBy (fun c -> c.Email)
+    |> List.filter (fun (_, xs) -> xs |> List.length > 1)
+    |> List.map (fun (email, xs) ->
+        {| Email = email
+           CustomerIds = xs |> List.map (fun c -> c.Id) |})
+
+[<EntryPoint>]
+let main args =
+    let builder = WebApplication.CreateBuilder(args)
+    // Emit consistent JSON for an external consumer — default
+    // System.Text.Json options are fine; documented for future tuning.
+    builder.Services.AddEndpointsApiExplorer() |> ignore
+    let app = builder.Build()
+
+    // Trivial root — lets a browser confirm the API is up. The
+    // `endpoints` list is the full contract surface (all 9 paths
+    // listed, including parameterised routes).
+    app.MapGet("/", Func<_>(fun () ->
+        {| name = "Factory-demo API (F#)"
+           version = "0.0.1"
+           endpoints =
+               [ "/"
+                 "/api/customers"
+                 "/api/customers/{id}"
+                 "/api/customers/{id}/activities"
+                 "/api/opportunities"
+                 "/api/opportunities/{id}"
+                 "/api/activities"
+                 "/api/pipeline/funnel"
+                 "/api/pipeline/duplicates" ] |} :> obj))
+        |> ignore
+
+    app.MapGet("/api/customers", Func<_>(fun () -> Seed.customers :> obj)) |> ignore
+    app.MapGet("/api/customers/{id:long}", Func<int64, IResult>(fun id ->
+        Seed.customers
+        |> List.tryFind (fun c -> c.Id = id)
+        |> function
+           | Some c -> Results.Ok c
+           | None -> Results.NotFound()))
+        |> ignore
+
+    app.MapGet("/api/opportunities", Func<_>(fun () -> Seed.opportunities :> obj)) |> ignore
+    app.MapGet("/api/opportunities/{id:long}", Func<int64, IResult>(fun id ->
+        Seed.opportunities
+        |> List.tryFind (fun o -> o.Id = id)
+        |> function
+           | Some o -> Results.Ok o
+           | None -> Results.NotFound()))
+        |> ignore
+
+    app.MapGet("/api/activities", Func<_>(fun () -> Seed.activities :> obj)) |> ignore
+    app.MapGet("/api/customers/{id:long}/activities", Func<int64, obj>(fun id ->
+        Seed.activities
+        |> List.filter (fun a -> a.CustomerId = id)
+        :> obj))
+        |> ignore
+
+    // Derived views that a frontend would otherwise compute client-
+    // side. Landing them server-side keeps the API contract tight.
+    app.MapGet("/api/pipeline/funnel", Func<_>(fun () -> pipelineFunnel () :> obj)) |> ignore
+    app.MapGet("/api/pipeline/duplicates", Func<_>(fun () -> duplicateEmails () :> obj)) |> ignore
+
+    app.Run()
+    0

samples/FactoryDemo.Api.FSharp/README.md

@@ -0,0 +1,101 @@
+# Factory-demo — JSON API (F#)
+
+**What this is:** A minimal F# ASP.NET Core Web API that serves
+the demo's seed data as JSON. Stack-independent — any frontend
+(Blazor / React / Vue / curl) consumes the same endpoints.
+
+**What this is NOT:** A pitch for Zeta as a data store. The
+demo sells the **software factory**, not the database layer.
+Backend is in-memory (v0) and will be swapped to Postgres (v1)
+without changing the public API contract.
+
+## Why this sample exists
+
+The factory-demo needs a JSON API that any frontend choice can
+consume. This API ships now so the backend is not on the
+critical path when the frontend stack is chosen.
+
+This is the F# reference implementation. A C# companion sample
+(`samples/FactoryDemo.Api.CSharp/`, sibling PR #147) is planned
+with the same 9 endpoints, matching JSON shapes, and identical
+seed. C# is the more popular .NET language, so it is the natural
+primary demo path; F# stays the reference because F# looks
+closer to math, which makes theorems over the algebra easier
+to express.
+
+## How to run
+
+```bash
+dotnet run --project samples/FactoryDemo.Api.FSharp/FactoryDemo.Api.FSharp.fsproj
+# API is up on http://localhost:5000 (or whatever ASP.NET picks).
+# curl it:
+curl http://localhost:5000/api/customers
+curl http://localhost:5000/api/pipeline/funnel
+curl http://localhost:5000/api/pipeline/duplicates
+```
+
+## Endpoints (v0)
+
+| Method | Path | Returns |
+|---|---|---|
+| GET | `/` | API metadata + endpoint list |
+| GET | `/api/customers` | All customers |
+| GET | `/api/customers/{id}` | Single customer, 404 if missing |
+| GET | `/api/customers/{id}/activities` | Activities for one customer |
+| GET | `/api/opportunities` | All opportunities |
+| GET | `/api/opportunities/{id}` | Single opportunity, 404 if missing |
+| GET | `/api/activities` | All activities |
+| GET | `/api/pipeline/funnel` | Per-stage count + $ total |
+| GET | `/api/pipeline/duplicates` | Customers sharing an email |
+
+All responses are JSON.
+
+## V0 seed data
+
+`Seed.fs` carries the in-memory seed (v1 will mirror a Postgres
+seed-data.sql under `samples/FactoryDemo.Db/`, not yet in repo):
+
+- 20 customers (trades contractors — plumbing, HVAC, electric, roofing, etc.)
+- 30 opportunities across 5 stages (Lead, Qualified, Proposal, Won, Lost)
+- 33 activities (calls, emails, SMS, notes)
+- 2 intentional email collisions to drive the duplicate-review scenario
+
+Seed is deterministic — restarting the server replays the same data.
+
+## What v1 adds
+
+- Postgres backing (Npgsql) wired against a planned
+  `samples/FactoryDemo.Db/` schema + seed (not yet in repo)
+- CRUD endpoints (POST / PUT / DELETE) — v0 is read-only
+- docker-compose for one-command Postgres + API
+- Environment-variable configuration for connection string
+
+Each of those is a follow-up PR.
+
+## Design notes
+
+- **`Microsoft.NET.Sdk.Web` SDK.** Pulls in ASP.NET Core via
+  framework reference — no package version edit in
+  `Directory.Packages.props` needed. Only `FSharp.Core` is an
+  explicit package reference.
+- **Minimal APIs over MVC.** F# + minimal APIs is a clean
+  combination: one file, no controllers, no heavy routing ceremony.
+- **Anonymous records for derived views.** `/api/pipeline/funnel`
+  returns an anonymous record with `Stage`, `Count`, and
+  `TotalCents` fields using F#'s `{| Stage = ...; Count = ...;
+  TotalCents = ... |}` syntax. Keeps the output shape local to
+  the endpoint handler.
+- **`System.Text.Json` defaults.** No converter customisation in v0.
+  If a frontend needs camelCase / different date shapes, add it as
+  a targeted follow-up rather than reshape everything.
+- **No OpenAPI / Swagger yet.** v0 intentionally minimal; Swagger
+  UI lands when endpoint count grows or frontend needs it.
+
+## What this does NOT do
+
+- Does not persist writes — v0 is read-only
+- Does not authenticate or authorise — no auth for the demo v0
+- Does not wire to Postgres — in-memory for v0
+- Does not expose algebraic-delta / retraction-native internals
+  to the frontend (that's the internal kernel sample's job; the
+  factory-demo audience gets standard CRUD shape)

samples/FactoryDemo.Api.FSharp/Seed.fs

@@ -0,0 +1,151 @@
+module Zeta.Samples.FactoryDemo.Api.Seed
+
+open System
+
+// Deterministic in-memory seed data for the API sample. Keep these
+// values stable so the same demo scenarios work whether the backing
+// store is Postgres (production-shape, planned follow-up) or this
+// in-memory fallback (zero-dependency, current).
+
+type Customer =
+    { Id: int64
+      Name: string
+      Email: string
+      Phone: string
+      Address: string
+      CreatedAt: DateTimeOffset
+      UpdatedAt: DateTimeOffset }
+
+type Opportunity =
+    { Id: int64
+      CustomerId: int64
+      Stage: string
+      AmountCents: int64
+      CreatedAt: DateTimeOffset
+      UpdatedAt: DateTimeOffset }
+
+type Activity =
+    { Id: int64
+      CustomerId: int64
+      OpportunityId: int64 option
+      Kind: string
+      Notes: string
+      OccurredAt: DateTimeOffset }
+
+// Fixed clock so the seed is deterministic. Any timestamp computed
+// from this is reproducible across restarts.
+let private now = DateTimeOffset(2026, 4, 23, 0, 0, 0, TimeSpan.Zero)
+let private ago (days: int) = now.AddDays(float -days)
+
+let customers : Customer list =
+    let mk id name email phone address =
+        { Id = id
+          Name = name
+          Email = email
+          Phone = phone
+          Address = address
+          CreatedAt = ago 120
+          UpdatedAt = ago 1 }
+    // Email collision #1: Alice Plumbing (1) and Aaron Smith (13) share alice@acme.example.
+    // Email collision #2: Bob HVAC (5) and Quincy Assistant (19) share bob@trades.example.
+    [ mk 1L  "Alice Plumbing LLC"        "alice@acme.example"    "555-0101" "123 Elm St, Portland OR"
+      mk 2L  "Benson Roofing"             "benson@roof.example"   "555-0102" "45 Oak Ave, Seattle WA"
+      mk 3L  "Crystal Electric"           "crystal@sparks.example" "555-0103" "9 Pine Rd, Boise ID"
+      mk 4L  "Delta HVAC & Mechanical"    "delta@hvac.example"    "555-0104" "700 Main St, Spokane WA"
+      mk 5L  "Bob HVAC Services"          "bob@trades.example"    "555-0105" "12 Bay Blvd, Tacoma WA"
+      mk 6L  "Evergreen Landscaping"      "info@evergreen.example" "555-0106" "88 Forest Ln, Eugene OR"
+      mk 7L  "Fairbanks Plumbing"         "contact@fairbanks.example" "555-0107" "5 River Rd, Anchorage AK"
+      mk 8L  "Granite Pest Control"       "hello@granite.example" "555-0108" "301 Stone Way, Boise ID"
+      mk 9L  "Highland Roofing Co"        "highland@roof.example" "555-0109" "22 Hill Dr, Bend OR"
+      mk 10L "Iron Tree Electric"         "iron@tree.example"     "555-0110" "17 Spruce St, Salem OR"
+      mk 11L "Jackson Pool Services"      "jackson@pools.example" "555-0111" "600 Lake Rd, Reno NV"
+      mk 12L "Klein Garage Doors"         "klein@doors.example"   "555-0112" "44 4th Ave, Medford OR"
+      mk 13L "Aaron Smith (new contact)"  "alice@acme.example"    "555-0113" "123 Elm St, Portland OR"
+      mk 14L "Lakeview Solar"             "lakeview@solar.example" "555-0114" "250 Shore Dr, Bellevue WA"
+      mk 15L "Mountain Well Drilling"     "mountain@wells.example" "555-0115" "12 Ridge Rd, Coeur dAlene ID"
+      mk 16L "Nightingale Security"       "ngale@secure.example"  "555-0116" "88 Watch Way, Vancouver WA"
+      mk 17L "Oak Hill Septic"            "oak@septic.example"    "555-0117" "14 Rural Rt 3, Gresham OR"
+      mk 18L "Prairie Window Cleaning"    "prairie@windows.example" "555-0118" "66 Glass Rd, Kennewick WA"
+      mk 19L "Quincy Assistant (Bob HVAC)" "bob@trades.example"   "555-0119" "12 Bay Blvd, Tacoma WA"
+      mk 20L "Redwood Tree Service"       "redwood@trees.example" "555-0120" "3 Canopy Ct, Hillsboro OR" ]
+
+let opportunities : Opportunity list =
+    let mk id custId stage amount =
+        { Id = id
+          CustomerId = custId
+          Stage = stage
+          AmountCents = amount
+          CreatedAt = ago 30
+          UpdatedAt = ago 2 }
+    [ mk 1L  1L  "Lead"      250000L
+      mk 2L  1L  "Qualified" 800000L
+      mk 3L  2L  "Lead"      180000L
+      mk 4L  3L  "Proposal"  450000L
+      mk 5L  3L  "Won"       120000L
+      mk 6L  4L  "Lead"      2200000L
+      mk 7L  4L  "Qualified" 600000L
+      mk 8L  5L  "Proposal"  350000L
+      mk 9L  5L  "Won"       900000L
+      mk 10L 6L  "Lead"      150000L
+      mk 11L 7L  "Qualified" 500000L
+      mk 12L 7L  "Proposal"  700000L
+      mk 13L 8L  "Won"       220000L
+      mk 14L 9L  "Lead"      300000L
+      mk 15L 9L  "Lead"      1800000L
+      mk 16L 10L "Qualified" 950000L
+      mk 17L 11L "Proposal"  1400000L
+      mk 18L 12L "Won"       380000L
+      mk 19L 13L "Lead"      50000L
+      mk 20L 14L "Proposal"  2500000L
+      mk 21L 14L "Qualified" 1100000L
+      mk 22L 15L "Won"       600000L
+      mk 23L 16L "Lead"      180000L
+      mk 24L 17L "Qualified" 270000L
+      mk 25L 18L "Lead"      80000L
+      mk 26L 19L "Proposal"  320000L
+      mk 27L 20L "Won"       450000L
+      mk 28L 20L "Lead"      210000L
+      mk 29L 2L  "Lost"      90000L
+      mk 30L 6L  "Lost"      400000L ]
+
+let activities : Activity list =
+    let mk id custId oppId kind notes daysAgo =
+        { Id = id
+          CustomerId = custId
+          OpportunityId = oppId
+          Kind = kind
+          Notes = notes
+          OccurredAt = ago daysAgo }
+    [ mk 1L  1L  (Some 1L)  "Call"  "Initial intake call — 3 units, basement finish" 14
+      mk 2L  1L  (Some 1L)  "Email" "Sent follow-up with rough estimate"              13
+      mk 3L  1L  (Some 2L)  "Call"  "Scope expanded to full house repipe"             6
+      mk 4L  2L  (Some 3L)  "Email" "Insurance paperwork sent for roof claim"         10
+      mk 5L  3L  (Some 4L)  "Call"  "Walkthrough scheduled for Tuesday"               8
+      mk 6L  3L  (Some 5L)  "Note"  "Payment received — closed won"                   3
+      mk 7L  4L  (Some 6L)  "Call"  "Commercial HVAC replacement — 6 rooftop units"   20
+      mk 8L  4L  (Some 6L)  "Email" "Technical specs and load calcs sent"             18
+      mk 9L  4L  (Some 7L)  "Call"  "Second opportunity — server-room cooling"        5
+      mk 10L 5L  (Some 8L)  "SMS"   "Confirmed 10am arrival window"                   2
+      mk 11L 5L  (Some 9L)  "Note"  "Deposit received; scheduled for next week"       7
+      mk 12L 6L  (Some 10L) "Email" "Initial inquiry from website"                    4
+      mk 13L 7L  (Some 11L) "Call"  "Alaska project — remote site, flew tools in"     30
+      mk 14L 7L  (Some 12L) "Email" "Proposal sent with permitting schedule"          15
+      mk 15L 8L  (Some 13L) "Note"  "Quarterly service contract signed"               45
+      mk 16L 9L  (Some 14L) "Call"  "Storm damage — needs quick turnaround"           1
+      mk 17L 9L  (Some 15L) "Email" "Large hotel roof — sent credentials package"     2
+      mk 18L 10L (Some 16L) "Call"  "Panel upgrade consult"                           11
+      mk 19L 11L (Some 17L) "SMS"   "Pool opening scheduled for May 1"                5
+      mk 20L 12L (Some 18L) "Note"  "Installed — 3yr warranty registered"             60
+      mk 21L 13L (Some 19L) "Email" "Intro call tomorrow 2pm"                         1
+      mk 22L 14L (Some 20L) "Call"  "Roof assessment + solar compatibility check"     12
+      mk 23L 14L (Some 21L) "Email" "Federal tax credit paperwork sent"               9
+      mk 24L 15L (Some 22L) "Note"  "Test-well results clean; contract signed"        25
+      mk 25L 16L (Some 23L) "Call"  "Camera system walkthrough"                       6
+      mk 26L 17L (Some 24L) "SMS"   "Septic pump appointment confirmed"               3
+      mk 27L 18L (Some 25L) "Email" "Storefront window quote"                         7
+      mk 28L 19L (Some 26L) "Call"  "Coordinating with Bob HVAC on combined job"      4
+      mk 29L 20L (Some 27L) "Note"  "Repeat customer — 2nd tree removal this year"    40
+      mk 30L 20L (Some 28L) "Email" "Quarterly pruning proposal"                      2
+      mk 31L 2L  (Some 29L) "Note"  "Customer went with competitor on price"          22
+      mk 32L 6L  (Some 30L) "Note"  "Lost deal — decided to self-install"             18
+      mk 33L 1L  None       "Email" "General follow-up — hope repipe went well"       90 ]