Add a List Details page for viewing and managing include/exclude list values

[zackcl]

Background

Today a list's values can only be seen and edited through the chip input in the Add/Edit List modal —
a ~2-row box where values can't be searched, copied, or edited. Beyond a handful of values, verifying
or maintaining a list is impractical.

The design in one sentence: every list gets its own details page — a list is created with its
metadata in a small modal, and its values are added and managed on the page. Chips are not used
anywhere for values.

Applies to every place that uses this list UI: include/exclude lists on experiments and feature
flags, segment lists, and Global Exclude.

How it works

1. Lists table — where lists are created and opened

The Include/Exclude Lists cards keep their current layout: same columns, toggles, and row actions.
[Add Include List] starts creating a new list (section 2). A list's name is a link to its
details page (section 3), where its values are viewed and managed. The edit action opens the
metadata modal (section 4).

Include Lists
Define include lists of participants...        (○ Include All)   [Add Include List]   ⋮

  Type          Values           Name             Enable      Actions
  ────────────────────────────────────────────────────────────────────
  schoolId      2,320 Values     My schools        (on)       edit  del
                                 ──────────
                                      └── link: opens the list's details page (section 3)

(Exclude Lists: same table without the Enable column. Segment-type lists have no values of their
own: their name links to the public segment's page and their edit action opens the segment picker
modal, as today. So across all list types, a name leads to that list's contents and the edit
action opens a small edit modal.)

2. Add List modal — metadata only

Creating a list collects just Type, Name, and Description. Create navigates directly to the new
list's details page, where the values are added.

Add Include List
  Type*
  [ Group: schoolId                              ▾ ]
  Name*
  [ My schools                                     ]
  Description (optional)
  [ West coast pilot schools                       ]
                                   Cancel   [Create]

3. List Details page — the single home for a list's values

Create lands here. The list starts empty, and the page prompts for values:

Experiments  >  Math Tutor Experiment  >  My schools
┌───────────────────────────────────────────────────────────────┐
│  My schools                                 [Edit] [Delete]   │
│  Include · Group: schoolId                                     │
│  "West coast pilot schools"                                    │
└───────────────────────────────────────────────────────────────┘
┌───────────────────────────────────────────────────────────────┐
│  Values (0)                                 [Add Values]  ⋮   │
│  ───────────────────────────────────────────────────────────  │
│  No values yet. Add values or import a CSV.                    │
└───────────────────────────────────────────────────────────────┘

[Add Values] opens the entry modal — the only place values are typed or pasted:

Add Values
  [ Type or paste values...                  ] [Add]
  Separate values with commas, tabs, or new lines.
  ┌────────────────────────────────────────────────┐
  │  1014190526892                              ×  │
  │  10855952okoai                              ×  │
  │  1085604lds9w3                              ×  │
  │  ...                                  (scroll) │
  └────────────────────────────────────────────────┘
  ⓘ 2 duplicates were skipped

                              Cancel   [Add 128 values]

• Typing a value and pressing Enter (or comma, or clicking [Add]) moves it into the list below;
  pasting comma/tab/newline-separated text (e.g. a spreadsheet column) splits it into individual
  values. Values keep the order they were typed or pasted in, so a paste can be checked against
  its source top-to-bottom, and rows can be removed before confirming.
• Duplicates are reported instead of silently dropped.

With values in place — just added, or opened later from the lists table — the Values section is a
searchable table:

┌───────────────────────────────────────────────────────────────┐
│  Values (2,320)         [Search...]         [Add Values]  ⋮   │
│  ───────────────────────────────────────────────────────────  │
│  Value                                             Actions    │
│  1014190526892                                    edit  del   │
│  10855952okoai                                    edit  del   │
│  1085604lds9w3                                    edit  del   │
│  ...                                                           │
└───────────────────────────────────────────────────────────────┘

• One value per row, with the total count and a search box. Values are plain text, so they
  can be selected and copied normally.
• edit fixes a value in place (one-field modal, duplicate-checked) · del removes it
  (with confirmation).
• ⋮ = Import CSV (append, or replace — replace shows a count confirmation first, e.g.
  "Replace all 2,320 values with 1,980 values from the file?") and Export CSV.
• [Edit] / [Delete] in the header = edit the list's metadata (section 4) / delete the whole list.
• Single-row changes apply immediately (like the enable toggles); bulk operations (CSV replace,
  list delete) always confirm first.

4. Edit List modal — same form as the Add List modal

Opened from the edit action in the lists table, or [Edit] on the details page. It is the
same Type/Name/Description form, prefilled. Add and Edit are symmetric, and neither contains values.

Edit Include List
  Type*
  [ Group: schoolId                              ▾ ]
  Name*
  [ My schools                                     ]
  Description (optional)
  [ West coast pilot schools                       ]
                                     Cancel   [Save]

(Whether Type should stay editable after creation — today changing it resets all values — is a
separate decision, tracked outside this story.)

Typical flows

Task	Steps
Create a list	[Add Include List] → Type/Name/Description → Create → lands on the list's page → [Add Values] or Import CSV
Open an existing list	click its name in the lists table → the list's details page
Verify a big upload	Import on the page → count and every value visible as rows; search or export
Fix a typo in a value	Page → search → edit row → correct it
Remove values	Page → search → delete row
Spreadsheet round-trip	Page → Export CSV → edit → Import CSV (replace, with count confirmation)
Rename / edit description	edit action in the lists table, or [Edit] on the page → metadata modal