# Phase 156 — tables: sticky headers + ellipsis on clipped labels

**Source:** owner UX audit 2026-10-03 (live interactive-browser pass): "sticky table headers (RAG/Sources/History — the tables are long; the header scrolls away)" + "At ~1,009px window width the rightmost table columns start clipped with no ellipsis hint on the 'Hidden'/'Edit' labels (the wrapper scrolls fine — just subtle)".
**Story:** n/a (audit-derived phase; the table machinery is phase 97's `97_kb_tree_catalog` + phase 86's `86_history_page_width`, both complete)
**Context:** `styles.css:: .table-wrap` (L2528–2534: `position: relative; background; border; radius; box-shadow; overflow-x: auto`) wraps `.docs-table` (`width: 100%; min-width: 640px`) — the RAG folder table (the `kb-folders-table` class), the Sources table (`#git-sources-table-wrap`, L3390), and the History table (the phase-50/86 width contract, L5583). The thead already has a TINTED background (L530 comment: "the thead tinted") — the sticky design needs it OPAQUE (rows must not show through on scroll). The clipped cells: the Sources table's `Hidden` checkbox label + `Ignore paths`/`Remove` buttons, the RAG table's `Edit` button, the History table's `Copy`/`Unshare`/`Create link`/`Delete` buttons — today a clipped label hard-cuts (no `text-overflow: ellipsis`). **The sticky constraint (the design's load-bearing fact):** a `position: sticky` `th` sticks to its NEAREST SCROLLING ANCESTOR — with `overflow-x: auto`, the wrapper's computed `overflow-y` is `auto` too, so the wrapper IS the scroll container; but it has no height bound, so it never scrolls vertically — the PAGE does. A sticky header in an unbounded wrapper therefore scrolls away with the page. The header sticks only if the wrapper itself is the vertical scroll region (a bounded `max-height`) — the standard scrollable-table-with-sticky-header pattern. That is the UX trade this phase makes (ASSUMPTION A1): the tables become bounded internal-scroll panels; the page no longer carries their height.

## Objective
On the three catalogue tables (RAG folders, Sources, History): the header row stays pinned while the user scrolls the table's own (now bounded) vertical scroll, and a clipped cell label shows `…` instead of a hard cut — the full text remains reachable (title/aria, the established idiom).

## Dependencies
- `97_kb_tree_catalog` (complete) — the RAG folder table + the `.table-wrap` card.
- `86_history_page_width` (complete) — the History table's width contract (the sticky design must keep it — the table stays full-width inside the bounded panel).
- `63_unambiguous_document_listing` (complete) — the Sources table's column idiom (the `Hidden` label + per-row actions).

## Design (shared by all tasks — the executor reads this, not the chat)
- **A1 (owner-locked):** the bounded-panel design — `.table-wrap` gains `max-height` (ASSUMPTION A2: `min(70vh, 64rem)` — the phase picks this; it must keep a 15-row table scrolling while a 3-row one fits without a scrollbar: the `min()` of a viewport fraction and a fixed cap does exactly that) + `overflow: auto` (superseding `overflow-x: auto` — the horizontal scroll contract is UNCHANGED: the table's `min-width: 640px` still triggers the wrapper's horizontal scroll at narrow widths; `overflow: auto` keeps both axes). The `th` sticky: `position: sticky; top: 0; z-index: 1;` on `.table-wrap table thead th` with an OPAQUE background (the existing tint made opaque — `background: var(--surface)` or the existing tint token, whichever the L530 comment names; check the current value and make it non-transparent; do NOT add a new palette variable — B3: the 17-variable contract is untouched, and an all-default theme stays byte-identical in the served CSS — the rule changes apply to BOTH themes equally).
- **A3 (owner-locked):** the ellipsis hint — the clipped cell LABELS get `max-width` + `overflow: hidden; text-overflow: ellipsis; white-space: nowrap;` (a `.cell-clip` class or a direct selector on the action-cell text nodes — the executor's choice; the `docs-table`'s existing cell padding is untouched). Coverage: the Sources `Hidden` checkbox label + `Ignore paths` + `Remove`; the RAG `Edit`; the History action buttons (`Copy`/`Unshare`/`Create link`/`Delete`). The FULL text stays reachable: every clipped label's control already carries its accessible name (the `Remove` button's `aria-label` names the full source — the phase-89 idiom; CHECK each of the other controls and add a `title`/`aria-label` where one is missing — the audit: the RAG `Edit` button, the History action buttons, the `Ignore paths` button — add the missing labels in the same task).
- **Scope guard:** the CHAT view's `.md-table-wrap` (L539 — the markdown-rendered tables) is a DIFFERENT class — UNTOUCHED (it has no card, no height bound; the design is for the catalogue tables only). The mobile ≤640px contract (PLAN §7.1) is re-verified in the E2E (the hamburger nav + the tables' horizontal scroll at ≤640px still work — the `max-height` must not break the mobile scroll model).

## Tasks
1. `01_sticky_header.md` — the bounded-panel `max-height`/`overflow: auto` + the opaque sticky `th` (all three catalogue tables share the class — one rule).
2. `02_ellipsis_hints.md` — the clipped-label ellipsis + the missing title/aria audit (the five control families).
3. `03_unit_pins.md` — the CSS contract pins (the existing styles-pinning idiom — the `:root`-drift test parses `styles.css`; extend the same suite).
4. `04_e2e_table_polish.md` — the dedicated Playwright suite (narrow viewport: the sticky offset + the computed ellipsis style + the mobile contract).

## Testing & Quality
- Unit: the CSS pins — `.table-wrap` carries `max-height: min(70vh, 64rem)` + `overflow: auto`; `.table-wrap table thead th` carries `position: sticky; top: 0; z-index: 1` + an opaque `background` (parse the stylesheet — the styles-pinning idiom, the `:root`-drift test's precedent); the `.md-table-wrap` rule is byte-UNCHANGED (the scope guard).
- Integration: none (CSS-only phase — the server pins stay byte-identical as regression guards).
- Coverage: **>90%** on modified code (CSS pinned by the source-level suite + the E2E).
- The phase is "Complete" only when the **entire** project test suite passes 100% (every test in the project, not just this phase's).
- E2E: `uv run pytest tests/e2e/test_table_ux_polish.py -v --no-cov` in isolation (DB up: `podman compose up -d db`).

## Documentation & Consistency
- The final pass reviews `README.md` and `AGENTS.md` in full against the project as it stands after this phase — fixing every inconsistency found, **including pre-existing ones not caused by the phase**.
- Tasks update `README.md`/`AGENTS.md` immediately when their own changes are user-visible (the bounded-panel scroll is a visible UX change — name it where the pages' layout is described, if anywhere).

## Completion Criteria
- [ ] all three catalogue tables: after scrolling the wrapper's vertical scroll, the `thead` stays at the panel top (the E2E asserts the `th`'s offsetTop ≈ 0 while the wrapper's scrollTop > 0)
- [ ] the horizontal-scroll contract is unchanged (narrow viewport: the table's `min-width: 640px` still scrolls inside the wrapper — the E2E)
- [ ] a clipped action label shows `text-overflow: ellipsis` (the E2E asserts the COMPUTED style on a forced-narrow cell — deterministic, no pixel assertions) and its full text is reachable (title/aria present on every clipped control)
- [ ] the mobile ≤640px contract holds (the hamburger nav + the table scroll — the E2E)
- [ ] `uv run pytest` green; the dedicated E2E green in isolation; `uv run ruff check . && uv run pyright` clean; `app/` coverage >90%
- [ ] one atomic commit per AGENTS.md rule 8 (`--no-gpg-sign`)