docs(collab): add user journey and E2E scenario requirements

Every feature issue must include a User Journey and E2E Scenarios
section before implementation begins.

Refs #48
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

COLLABORATING.md

@@ -43,6 +43,42 @@ Repeat for each new behavior.
 - The Refactor step must not change behavior — if a test breaks, the refactor introduced a bug.
 - If a bug is reported with no test, write the failing test first, then fix it.
 
+## User Journeys & E2E Acceptance Criteria
+
+Every `feature` issue must include two sections before any implementation begins:
+
+### 1. User Journey
+
+A plain-prose description of the steps a user takes to get value from the feature. Written from the user's perspective, not the implementation's:
+
+> User opens a document, clicks "History", sees a chronological list of changes with editor name and timestamp. Clicking a row expands the old vs. new values.
+
+This makes the scope concrete and prevents scope creep — anything not in the journey is out of scope for the issue.
+
+### 2. E2E Scenarios
+
+One or more acceptance criteria written as Playwright-ready scenarios. These become the outermost Red test in the TDD cycle — no feature is considered done until all its E2E scenarios pass:
+
+```
+Scenario: View edit history of a document
+  Given I am on a document detail page
+  When I click the "History" tab
+  Then I see at least one revision entry
+  And each entry shows the editor's name and a timestamp
+```
+
+Use this format consistently. It maps directly to `test.describe` / `test` blocks in the Playwright spec.
+
+### Where this fits in the workflow
+
+```
+Issue (Journey + Scenarios) → Red E2E test → Implementation → Green
+```
+
+The scenarios in the issue are the contract. Write them before planning, treat them as failing tests from day one.
+
+---
+
 ## Issue Tracking (Gitea)
 
 All work is tracked in **Gitea** at `http://192.168.178.71:3005` (repo `marcel/familienarchiv`). Never use todo files or CLAUDE.md notes as a substitute.