docs: capture design from walk-with-me (CONTEXT, DESIGN, ADR-0001)

CONTEXT.md

@@ -0,0 +1,67 @@
+# photofetch
+
+Pick a Napta **Project** and see a grid of its **Members** — each shown with their
+Slack **Avatar**, name, and **Role**. The shared vocabulary below is the ubiquitous
+language: it must appear verbatim in conversation, code, tests, commits, and docs.
+
+## Language
+
+**Project**:
+A Napta project that people are staffed on; the unit you select to see its team.
+_Avoid_: mission, engagement.
+
+**Person**:
+An employee in Napta (a Napta `user`), carrying an email, first/last name, and Position.
+_Avoid_: collaborator, resource, user (ambiguous — there are no app accounts).
+
+**Staffing Assignment**:
+A Napta `user_project` row linking one Person to one Project; may be real or `simulated`.
+_Avoid_: allocation, booking.
+
+**Member**:
+A Person with a real (non-`simulated`) Staffing Assignment on the selected Project who is still an active employee — one cell in the grid.
+_Avoid_: teammate, staff.
+
+**Role**:
+A Member's Napta job Position (`user_position`), shown under their name.
+_Avoid_: title, grade, seniority.
+
+**Match**:
+The link from a Member to their Slack profile, made by equal email. A Member is _matched_ or _unmatched_.
+_Avoid_: lookup, mapping.
+
+**Avatar**:
+A matched Member's Slack profile picture. Unmatched Members fall back to an initials Avatar.
+_Avoid_: photo, picture, image.
+
+**Selection**:
+The set of one or more Projects currently chosen, whose teams are shown together.
+_Avoid_: filter.
+
+**Project Group**:
+One selected Project plus its Members — a section in the grid and a folder in an Export.
+_Avoid_: section, bucket.
+
+**Export**:
+A downloadable zip of Member Avatars, organized as one folder per Project Group (folder named after the Project).
+_Avoid_: download, dump.
+
+## Relationships
+
+- A **Project** has many **Staffing Assignments**; each Assignment links one **Person**.
+- A **Member** is a **Person** with a qualifying **Staffing Assignment** on a selected **Project**.
+- A **Member** has exactly one **Role** and at most one **Avatar** (via an email **Match**).
+- A **Selection** contains one or more **Projects**; each renders as a **Project Group**.
+- A Person staffed on several selected **Projects** appears in each of those **Project Groups**.
+- An **Export** writes one folder per **Project Group**, holding its Members' **Avatar** files.
+
+## Example dialogue
+
+> **Dev:** "When I pick a **Project**, do I show every **Person** who has a **Staffing Assignment** on it?"
+> **Domain expert:** "Only real ones — drop the `simulated` assignments, and drop people who've left."
+> **Dev:** "And if a **Member**'s email has no **Match** in Slack?"
+> **Domain expert:** "Still show them — initials **Avatar**, real name and **Role**. A missing photo isn't a missing person."
+
+## Flagged ambiguities
+
+- "user" is avoided: Napta calls a Person a `user`, but photofetch has no login/accounts, so the word would mislead. A Person on the selected Project is a **Member**.