feat: add ephemeral-counter and ephemeral-todos examples by adnaan · Pull Request #41 · livetemplate/examples

adnaan · 2026-03-31T20:12:46Z

Summary

Add ephemeral-counter/ — demonstrates WithEphemeralState() with an in-memory store as the source of truth. No SQLite dependency — just a mutex-protected counter.
Add ephemeral-todos/ — demonstrates WithEphemeralState() with SQLite for CRUD. Supports both WebSocket and HTTP-only modes via LVT_WEBSOCKET_DISABLED=true.
Update go.mod to livetemplate v0.8.11 (which includes WithEphemeralState())

What is Ephemeral State?

With WithEphemeralState(), LiveTemplate skips session persistence entirely. Every request starts with fresh state rebuilt via Mount(). The database (or any external store) is the canonical source of truth — LiveTemplate state is just a rendering projection.

Test plan

Both examples build (go build -o /dev/null ./ephemeral-counter/ ./ephemeral-todos/)
Chromedp E2E tests: initial render, actions, page refresh loads from DB
Updated README.md examples table
Updated test-all.sh WORKING_EXAMPLES

Implements examples for livetemplate/livetemplate#299.

🤖 Generated with Claude Code

Demonstrate WithEphemeralState() from livetemplate v0.8.11 (#299). - ephemeral-counter: in-memory store as source of truth, state rebuilt from it on every request. No SQLite — just a mutex-protected counter. - ephemeral-todos: SQLite as source of truth, CRUD with ephemeral state. Supports both WebSocket and HTTP-only modes. - Both include chromedp E2E tests following existing patterns. - Updated go.mod to livetemplate v0.8.11. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

Adds two new LiveTemplate examples showcasing the new WithEphemeralState() option, plus supporting repo updates (deps/docs/scripts) so the examples build and run in CI like the rest of the examples suite.

Changes:

Add ephemeral-counter/ example using an in-memory mutex-protected “DB” as the canonical store with WithEphemeralState().
Add ephemeral-todos/ example using SQLite as the canonical store with WithEphemeralState(), plus E2E coverage.
Bump github.com/livetemplate/livetemplate to v0.8.11 and register the new examples in README + test-all.sh.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
`test-all.sh`	Adds the two new examples to the WORKING_EXAMPLES list so they are built/tested.
`README.md`	Documents the new examples in the examples table.
`go.mod`	Updates LiveTemplate dependency to `v0.8.11` (for `WithEphemeralState()`).
`go.sum`	Records new module sums for the updated LiveTemplate version.
`ephemeral-counter/main.go`	New in-memory ephemeral-state counter server using `WithEphemeralState()`.
`ephemeral-counter/counter.tmpl`	Template for the ephemeral counter UI and client bootstrapping.
`ephemeral-counter/counter_test.go`	Chromedp E2E test validating refresh behavior in ephemeral mode.
`ephemeral-todos/main.go`	New SQLite-backed ephemeral-state todos server + optional WebSocket disable via env var.
`ephemeral-todos/todos.tmpl`	Template for the todos UI and client bootstrapping.
`ephemeral-todos/todos_test.go`	Chromedp E2E test for initial render, add, and refresh-from-DB behavior.

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Copilot · 2026-03-31T20:17:38Z

ephemeral-todos/todos.tmpl

+            <form>
+                <fieldset role="group">
+                    <input type="text" name="title" placeholder="What needs to be done?" required>
+                    <button type="submit">Add</button>
+                </fieldset>


The Add form defaults to GET because it omits method="POST". For the HTTP-only / progressive-enhancement behavior (and consistency with other examples), set method="POST" so submissions route through LiveTemplate actions without relying on query params.

Copilot · 2026-03-31T20:17:38Z

ephemeral-todos/todos.tmpl

+            <ul>
+                {{range .Items}}
+                <li>
+                    <label>
+                        <input type="checkbox" name="toggle" value="{{.ID}}" {{if .Done}}checked{{end}}>
+                        {{if .Done}}<s>{{.Title}}</s>{{else}}{{.Title}}{{end}}
+                    </label>
+                    <button name="delete" value="{{.ID}}" class="outline secondary" style="padding: 0.25rem 0.5rem; font-size: 0.8rem;">Delete</button>
+                </li>


Toggle/Delete controls are not inside a
and the checkbox doesn’t auto-submit, so Toggle() / Delete() won’t be triggered in non-JS / HTTP-only mode (and may not send a stable id parameter). Wrap each item’s toggle/delete in method="POST" forms (with a hidden id field) and submit the toggle form on checkbox change, as done in other todo examples.

Copilot · 2026-03-31T20:17:39Z

ephemeral-todos/main.go

+func (c *TodoController) Toggle(state TodoState, ctx *livetemplate.Context) (TodoState, error) {
+	id, _ := strconv.Atoi(ctx.GetString("value"))
+	_, err := c.DB.Exec("UPDATE todos SET done = NOT done WHERE id = ?", id)


Toggle()/Delete() parse the id from ctx.GetString("value") and ignore Atoi errors. This makes the parameter contract unclear and can silently operate on id=0 when the param is missing/invalid. Prefer an explicit parameter (e.g., "id") and return a validation error when conversion fails.

Copilot · 2026-03-31T20:17:39Z

ephemeral-todos/main.go

+	db, err := sql.Open("sqlite", "file:todos.db?cache=shared&mode=rwc")
+	if err != nil {
+		slog.Error("Failed to open database", "error", err)


initDB() opens a relative on-disk DB (todos.db) in the repo/example directory. This will leave an untracked file after running the example/tests and can make the E2E test flaky (it expects an empty DB on initial load). Consider defaulting to an in-memory DB or a temp dir path, and/or allow overriding the DB path via env var so tests can isolate state.

Suggested change

db, err := sql.Open("sqlite", "file:todos.db?cache=shared&mode=rwc")

if err != nil {

slog.Error("Failed to open database", "error", err)

// Allow overriding the DB path/DSN via environment variable so tests and

// deployments can control persistence and isolation. By default, use an

// in-memory SQLite database to avoid creating on-disk files in the repo.

dsn := os.Getenv("EPHEMERAL_TODOS_DB")

if dsn == "" {

dsn = "file:memdb1?mode=memory&cache=shared"

}

db, err := sql.Open("sqlite", dsn)

if err != nil {

slog.Error("Failed to open database", "error", err, "dsn", dsn)

Copilot · 2026-03-31T20:17:39Z

ephemeral-todos/main.go

+			return state, err
+		}
+		state.Items = append(state.Items, t)
+	}


Mount() iterates rows.Next() but never checks rows.Err() after the loop. Add a rows.Err() check to surface any scan/iteration errors from the driver.

Suggested change

}

}

if err := rows.Err(); err != nil {

return state, err

}

Copilot · 2026-03-31T20:17:39Z

ephemeral-todos/main.go

+		return state, err
+	}
+
+	id, _ := result.LastInsertId()


Submit() ignores the error return from result.LastInsertId(). If the driver can’t provide it, id may be 0 and the returned state will diverge from the DB. Handle the error (or query the inserted row id) before appending to state.Items.

Suggested change

id, _ := result.LastInsertId()

id, err := result.LastInsertId()

if err != nil {

return state, err

}

Copilot · 2026-03-31T20:17:40Z

ephemeral-todos/todos_test.go

+func TestEphemeralTodosE2E(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping E2E test in short mode")
+	}
+


This example claims to support HTTP-only mode via LVT_WEBSOCKET_DISABLED=true, but the E2E test only exercises the WebSocket path (WaitForWebSocketReady). Add a test variant that starts the server with LVT_WEBSOCKET_DISABLED=true and waits for client readiness in HTTP mode (similar to ws-disabled/ws_disabled_test.go) to prevent regressions.

Copilot AI review requested due to automatic review settings March 31, 2026 20:12

Copilot started reviewing on behalf of adnaan March 31, 2026 20:13 View session

Copilot AI reviewed Mar 31, 2026

View reviewed changes

adnaan merged commit 133bd41 into main Mar 31, 2026
16 checks passed

adnaan deleted the feat/ephemeral-examples branch March 31, 2026 20:27

adnaan mentioned this pull request Apr 3, 2026

upgrade 08.14 #49

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feat: add ephemeral-counter and ephemeral-todos examples#41

feat: add ephemeral-counter and ephemeral-todos examples#41
adnaan merged 1 commit intomainfrom
feat/ephemeral-examples

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-	db, err := sql.Open("sqlite", "file:todos.db?cache=shared&mode=rwc")
-	if err != nil {
-		slog.Error("Failed to open database", "error", err)
+	// Allow overriding the DB path/DSN via environment variable so tests and
+	// deployments can control persistence and isolation. By default, use an
+	// in-memory SQLite database to avoid creating on-disk files in the repo.
+	dsn := os.Getenv("EPHEMERAL_TODOS_DB")
+	if dsn == "" {
+		dsn = "file:memdb1?mode=memory&cache=shared"
+	}
+	db, err := sql.Open("sqlite", dsn)
+	if err != nil {
+		slog.Error("Failed to open database", "error", err, "dsn", dsn)

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adnaan commented Mar 31, 2026

Summary

What is Ephemeral State?

Test plan

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