> ## Documentation Index
> Fetch the complete documentation index at: https://docs.reasonos.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Ten minutes with Casework

> Understand a small service, change it, verify it with RBS, preview it, and work on it together — in one branch workspace.

Casework is a small sample service: a team's case queue with a browser page, an HTTP API, and RBS build and test targets. This walkthrough adds one improvement the team asks for — an **Overdue cases** filter — and shows the result at every step. It assumes a project already imported from the Casework sample with a branch workspace open on `cases.go`.

## 1. Read the code (1 minute)

Open `web.go` (the page and its **Show cases** selector) and `cases.go` (`selectCases`, and the fixed demonstration date `demoToday`, which keeps the walkthrough repeatable).

## 2. Prove the baseline and see it running (2 minutes)

```sh theme={null}
rbs build //:server && rbs test //:test --no-cache
```

Expect `Test PASSED: test` and `Successfully passed all targets`.

```sh theme={null}
CASEWORK_ADDR=127.0.0.1:8177 rbs run //:server
```

Expect `Casework demo: http://127.0.0.1:8177 (synthetic data; fixed demo date 2026-09-14)`; the process keeps running. Open **Tools → Browser**, enter that URL: the page lists four cases under **All**. The preview is served through ReasonOS; you never connect to the branch server directly.

## 3. Describe the behavior as a test, watch it fail (2 minutes)

Append to `cases_test.go` and save:

```go theme={null}
func TestOverdueCases(t *testing.T) {
	got, err := selectCases(sampleCases(), "overdue")
	if err != nil {
		t.Fatalf("overdue filter refused: %v", err)
	}
	if len(got) != 1 || got[0].ID != "CW-101" {
		t.Fatalf("overdue = %+v; want exactly CW-101 (open, due 2026-09-12, before %s)", got, demoToday)
	}
	for _, c := range got {
		if c.ID == "CW-102" {
			t.Fatalf("due-today case CW-102 must not be overdue: %+v", c)
		}
		if c.ID == "CW-104" {
			t.Fatalf("closed case CW-104 must not be overdue: %+v", c)
		}
	}
}
```

In a second terminal: `rbs test //:test`. Expect `--- FAIL: TestOverdueCases` with `overdue filter refused: status must be all, open or closed` — the service does not know the word yet.

## 4. Make the change, pass the gate (2 minutes)

Replace `selectCases` in `cases.go`:

```go theme={null}
func selectCases(cases []Case, status string) ([]Case, error) {
	if status != "" && status != "all" && status != "open" && status != "closed" && status != "overdue" {
		return nil, fmt.Errorf("status must be all, open, closed or overdue")
	}
	selected := make([]Case, 0, len(cases))
	for _, c := range cases {
		matches := status == "" || status == "all" || c.Status == status
		if status == "overdue" {
			matches = c.Status == "open" && c.Due < demoToday
		}
		if matches {
			selected = append(selected, c)
		}
	}
	return selected, nil
}
```

Add the option in `web.go` after **Closed cases**: `<option value="overdue">Overdue cases</option>`. Save both, then:

```sh theme={null}
rbs test //:test --no-cache
rbs coverage //:test
```

Expect `Result: PASSED` and a line coverage above the sample's 80% floor.

## 5. Preview the improvement (1.5 minutes)

In the first terminal press Ctrl-C and run the same `rbs run` command again (the binary is rebuilt). In the Browser panel load `http://127.0.0.1:8177/?demo=2` (re-entering an unchanged URL does not reload; a changed query does) and choose **Overdue cases**: exactly **CW-101** appears. All, Open and Closed still work.

## 6. Work on it together (1 minute)

Open the same branch workspace in a second browser window. In that window use **Split Editor Right** and open `web.go` in the right-hand pane (under one sign-in, a second window opening the file in the same pane position takes over the first window's connection; the split pane is the verified way around that — see [Collaboration](/editor/collaboration)). Turn **Collab** on in both windows. Type ` (late work)` after `Overdue cases` in the second window: the first window shows it as it is typed — press Cmd+F there and search `late work` if the line is wider than the pane. Save in the second window; the branch's file now carries the shared edit.

## What this shows, and what it does not

Understand → change → verify → preview → collaborate in one workspace, with real build and test results at each step. Two windows on one login show shared editing, not two authenticated people; the sample uses synthetic data and a fixed date on purpose.