fix(spec)!: refuse a padded groupByField on kanban, gantt and timeline instead of handing the renderer a lookup that always misses (#18695)

Fixes #17499
Clause-②: no

## What changed

`KanbanConfigSchema.groupByField` (**required**),
`GanttConfigSchema.groupByField` and `TimelineConfigSchema.groupByField`
were bare `z.string()`, so `' stage'` was valid authored metadata. All
three now carry the **non-padded** pattern this repo already chose for
the same defect on the sibling axis — `grouping.fields[].field`, landed
as `f8e5790593` (#17360 / PR #17498), which scoped this axis out by
name.

The refusal is addressed to the offending key (`kanban.groupByField`,
`gantt.groupByField`, `timeline.groupByField`), quotes the offending
spelling so the invisible whitespace is visible, and carries the name to
write instead.

### Reusing the precedent, and the three places it does not fit

- The regex is the precedent's, not a second one. Its module-private
constant is renamed `GROUPING_FIELD_NON_PADDED_PATTERN` to
`NON_PADDED_FIELD_NAME_PATTERN` and now serves both axes. No exported
symbol moves (`check:api-surface` is clean with no regeneration).
- **The kanban key is REQUIRED** — the precedent's is not. That is the
whole reason this is its own card: a padded value there cannot be
withdrawn by omitting the key, so a `.trim()` producer would be the
author's only feedback channel and it would say nothing. The refusal is
sharper here, not milder.
- **Refuse, not `.trim()`** — the precedent's stated reason, re-checked
and unchanged: a trimming schema makes `' stage'` and `'stage'` silently
equivalent, the consumer-tolerance direction AGENTS.md #0.1 refuses.
None of these three rows honestly wants the other answer, and the
required key is the strongest case against it.
- **No ruling citation in the message.** The precedent's message ends
with its ruling date; ruling C on objectui#7347 is about
`grouping.fields[].field` and explicitly not about this axis, so quoting
it here would attribute a decision nobody made. The code comment says
so.

## ADR-0087 disposition: `registered`, and the entry is in this PR

The changeset carries an `adr-0087: registered
ui-list-view-groupbyfield-padded-refused` marker (the HTML-comment form
the gate reads), and
`packages/spec/src/migrations/entries/semantic/18.ui-list-view-groupbyfield-padded-refused.ts`
registers it under protocol major 18, with the regeneration lap
committed beside it.

Why `registered` and not a `not-required` category, measured against the
gate's closed vocabulary:

| category | verdict here |
|:--|:--|
| `unpublished` | refused — `@objectstack/spec` publishes to npm. |
| `already-registered` | **false**. The precedent's entry scopes itself
to `grouping.fields[].field` and says in its own text that the
`groupByField` axis is not touched by it. |
| `no-migration-prescription` | refused — the changeset body carries a
FROM/TO block, and there genuinely is a prescription: stored views with
a padded name are refused on their next authoring-path save and must be
re-authored. |
| `runtime-interface-only` | refused — this is a spec schema, not a
runtime TS interface. |
| `type-surface-only` | refused — the narrowing is a parse-time refusal,
not a type-only change. |

The same-defect precedent took `registered` with a new semantic entry,
for the same stored-metadata reason.

**The regeneration lap, and why two of its three files show no diff.**
`pnpm --filter @objectstack/spec gen:migration-registry` inserted the
entry into `registry.ts`'s generated region (56 lines, insertion-only,
comment run carried through; nothing hand-edited inside the markers).
`gen:spec-changes` and `gen:upgrade-guide` both ran and wrote
byte-identical files: each projects majors up to `PROTOCOL_VERSION`,
which is `17.0.0`, and this entry registers under **18**. The control is
the landed sibling `f8e5790593` — its file list touched neither
projection either. `check:migration-registry`, `check:spec-changes` and
`check:upgrade-guide` are all green.

## Evidence

**Red before green — ablation, on-disk proof, hash-verified restore.**
The fix was committed first; the mutation removed the three
`superRefine` calls from `packages/spec/src/ui/view.zod.ts` (the subject
resolves through the same-package relative import `./view.zod`, so there
is no `dist` leg to prove — the test never resolves through `exports`).

```
BEFORE   HEAD blob 6ff7ba3 == on-disk hash; 3 occurrences
MUTATED  on-disk hash bf9424b852ac545affc8d69abc8548e1114817da; 0 occurrences; git diff --stat: 3 deletions
ABLATED  24 failed | 40 passed   (exit 1)
RESTORE  git checkout HEAD -- packages/spec/src/ui/view.zod.ts; on-disk hash back to 6ff7ba3…, git status clean
GREEN    64 passed | 387 skipped (exit 0)
```

The direction was predicted before the run and observed as predicted:
turning red, 24 of the 64 arms. The 40 that stayed green are the LIT and
no-trim arms, which is what makes the 24 a reading rather than a
restatement.

**⭐ LIT — the narrowing does not over-reach.** Every distinct
`groupByField` spelling this repo carries still parses, on all three
schemas: harvested across every `.ts` / `.tsx` / `.mdx` / `.json` /
`.mjs` outside `node_modules`, **14 distinct literals, zero of them
padded**. `owner.name` is the load-bearing member and is pinned — these
keys hold a field reference, not a machine name, which is why the
snake_case grammar `/^[a-z_][a-z0-9_]*$/` is the wrong vocabulary
(`packages/lint`'s `validate-list-view-field-refs.test.ts` carries
`kanban: { groupByField: 'owner.name' }` in a case asserting no
findings; that suite is green here, 137 tests). Three of the 14 —
`'warning'`, `'error'`, a bracketed `select_or_status_field` placeholder
— are a severity-map value and prose in a completeness hint, so they are
not authored names and are not pinned.

**⭐ DARK — three readings that must be 0, before and after.**

| reading | before | after |
|:--|:--|:--|
| other bare `z.string()` keys in `view.zod.ts` reached by this change |
0 | 0 — the edit touches exactly the 3 `groupByField` declarations; `git
diff` shows 3 changed property sites and no other schema key. A
per-schema test probes every sibling string key (`summarizeField`,
`titleField`, `startDateField`, `endDateField`, `progressField`,
`colorField`) with a padded value and requires it to still parse. |
| `authorable-surface/` rows moved | 0 | 0 — `check:authorable-surface`
green with no regeneration; a value-level refusal adds no key. |
| `api-surface/` entries moved | 0 | 0 — `check:api-surface` green with
no regeneration; the published type surface is byte-unchanged. |

**Which gate can actually go red on this — measured, not guessed.**
`check:docs` reads these three `describe()` strings: it exited **1**
naming `content/docs/references/ui/view.mdx` and
`content/docs/references/ui/component.mdx` before `gen:schema &&
gen:docs`, and 0 after. `check:adr-0087-registration` reads the
changeset and exited **1** before the ledger entry landed, naming
exactly the missing id, and **0** after it — red before green on that
gate too. The remaining 13 of the 15 spec artifact gates were green
throughout — they structurally cannot see a value-level refine, and are
recorded as DARK rather than claimed as coverage.

**Commands run.** The schema and test blobs have not moved since the
first lap (`view.zod.ts` is `6ff7ba320a8fa445fa34e421b39716359194bc1b`
at both heads and on disk, `view.test.ts` is `162772c6…`), so the
ablation above stands unrepeated; every other reading below was re-taken
at `ca0dd6ce0e` after the ledger entry landed:

| command | result |
|:--|:--|
| `pnpm --filter @objectstack/spec test` | 485 files / **13932 passed**
|
| `pnpm --filter @objectstack/spec typecheck` | exit 0 (test layer
compiles; debt ledger held) |
| `pnpm --filter @objectstack/spec check:generated` | **all 15 artifacts
up to date** (both laps) |
| `pnpm --filter @objectstack/lint exec vitest run
src/validate-list-view-field-refs.test.ts
src/runtime-gate.view-writes.test.ts` | 137 passed |
| `pnpm exec eslint . --no-inline-config` | **6819 files, 0 errors, 0
warnings** — the whole population at `ca0dd6ce0e`, no narrowing claimed;
both files this lap added or changed are provably in the run |
| `pnpm check:nul-bytes` | 8804 files, no raw control bytes |
| `pnpm check:empty-changeset`, `check-changeset-no-major.mjs` | exit 0
|
| `check-adr-0087-registration.mjs` | **exit 0** — `1 declared-breaking
changeset(s), each carrying an ADR-0087 disposition … registered
ui-list-view-groupbyfield-padded-refused (new here)` |

## Acceptance notes

- The empty string still parses on all three keys, deliberately: this
card narrows padding only, and widening the pattern to catch `''` would
be a second, undeclared narrowing riding on it. On the required kanban
key a blank name is a blank board, refused one layer down by the
field-reference rules, not by this pattern.
- Noted, not filed — objectui's `packages/i18n` carries `groupByField:
'Group by field'` / `'分组字段'`. Those are i18n label entries keyed by the
same name, not values of this spec key, so they are neither affected nor
evidence about accepted values. Recorded because a reader harvesting the
sibling repo will hit them.
- Noted, not filed —
`packages/spec/src/kernel/functional-completeness.ts` documents the
kanban fallback chain as `groupBy = groupByField || groupField || ...`,
and `groupField` is a live legacy alias declared in objectui, not in
this repo. Nothing here is wrong; it is the context a future reader of
this key needs. Carrier: whoever next touches the kanban completeness
hint.

Authored by the `domain:spec` execution seat, session
`session_01JbZnqu8bt6YqfJsr9vaFb3`.


---
_Generated by [Claude Code](https://claude.ai/code)_

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-bill

.changeset/17499-groupbyfield-non-padded.md

@@ -0,0 +1,49 @@
+---
+"@objectstack/spec": minor
+---
+
+fix(spec)!: `groupByField` refuses a padded field name on kanban, gantt and timeline instead of handing the renderer a lookup that always misses (#17499)
+
+**BREAKING** — an accept-set narrowing on three published authoring keys. `KanbanConfigSchema.groupByField` (**required**), `GanttConfigSchema.groupByField` and `TimelineConfigSchema.groupByField` were bare `z.string()`, so `' stage'` was valid authored metadata; all three are now refused at parse. Shipped as `minor` under the repo's launch-window convention for accept-set narrowings, the same as the sibling axis in #17360. Stored metadata carrying a padded `groupByField` now fails validation and must be re-authored — the hand-migration prescription is registered under protocol major 18 as `ui-list-view-groupbyfield-padded-refused`.
+
+## What was wrong
+
+The padded name never failed anywhere. It failed to *group*.
+
+These three keys name a field the consumer looks up on **every row, by that name**. Measured in objectui at `dda8f3815`: the kanban board resolves its lane as `laneField = groupByField || groupField || detectStatusField(objectDef)` and buckets cards by `card[laneField]`; `ObjectGantt`'s `groupByAccessor` splits the name on `.` and walks the backing record (`resolvePath(task.data, field)`); the timeline groups its rows the same way. The server answers under the unpadded name, so a padded spelling reads `undefined` on every row and the board collapses into one `Uncategorized` lane — the gantt and the timeline into one ungrouped bucket — holding every record.
+
+That is a silent wrong answer that reads as a true statement about the data: a user looking at one giant lane cannot tell it apart from a dataset where the field genuinely is empty. Nothing weaker than a parse refusal is honest about it.
+
+`packages/lint`'s `validate-list-view-field-refs` already calls this consequence out for `kanban.groupByField` (*"collapses every card into the uncolumned bucket"*), and grades that position `error` — but that rule only runs where an app is validated against its object definitions. The producer accepted the value regardless, which is the hole this closes.
+
+## What it does now
+
+Each of the three carries the **non-padded** pattern — no leading and no trailing whitespace — and the refusal is addressed to the offending key (`kanban.groupByField`, `gantt.groupByField`, `timeline.groupByField`), names the offending spelling verbatim so the whitespace an author cannot see in an editor is visible in the message, and carries the name to write instead.
+
+⛔ **Not a `.trim()`.** A trimming schema makes `' stage'` and `'stage'` silently equivalent, which is the consumer-tolerance direction AGENTS.md #0.1 refuses: the padded spelling is a mistake the author should be told about, not a dialect the producer quietly normalises away. On the **required** kanban key this is sharper than on the sibling axis — an author cannot withdraw the value by omitting the key, so a normalising producer would be the author's only feedback channel and it would say nothing.
+
+## FROM → TO
+
+| you wrote | write instead |
+|:--|:--|
+| `kanban: { groupByField: ' stage' }` | `kanban: { groupByField: 'stage' }` |
+| `gantt: { groupByField: 'owner ' }` | `gantt: { groupByField: 'owner' }` |
+| `timeline: { groupByField: 'team\n' }` | `timeline: { groupByField: 'team' }` |
+
+The remedy is always the same: write the field name exactly as the object declares it and the server answers under. If a board has been silently showing one `Uncategorized` lane, re-authoring the name is also the fix for that.
+
+## Scope — what is deliberately NOT narrowed
+
+- **The empty string is unchanged.** It still parses, exactly as before, on all three keys. This narrowing exists for the **silent** case; widening the pattern to catch `''` would be a second, undeclared narrowing riding on this one.
+- **This is not the snake_case machine-name grammar.** `packages/spec` spells `/^[a-z_][a-z0-9_]*$/` inline for object, field and tool **names**, and these keys deliberately do not take it: a `groupByField` holds a field **reference**, and a dotted relationship path (`owner.name`) is an in-tree spelling of one — `packages/lint`'s `validate-list-view-field-refs.test.ts` carries `kanban: { groupByField: 'owner.name' }` in a case asserting no findings.
+- **The sibling axis `grouping.fields[].field`** already landed this rule in #17360 / PR #17498; this change reuses that pattern rather than declaring a second one.
+
+## Who is affected, measured
+
+Every `groupByField` spelling in this repo parses unchanged. Harvested across every `.ts` / `.tsx` / `.mdx` / `.json` / `.mjs` outside `node_modules`: **14 distinct literals, zero of them padded** (`'warning'` / `'error'` are severity-map values in `packages/lint` and `'<select_or_status_field>'` is prose inside a completeness hint, so neither is an authored name). Nothing in the tree reddens, and no fixture had to be rewritten to keep it green.
+
+Outside the repo, only metadata that was already grouping wrongly is affected: a padded `groupByField` has never produced a correct board, gantt or timeline on any renderer.
+
+Clause-②: no (narrowing) — no key is added, removed or renamed, no exported symbol moves (`check:api-surface` clean with no regeneration), and no registry row is added. The accept set narrows back to what the key's description already claimed.
+
+<!-- adr-0087: registered ui-list-view-groupbyfield-padded-refused -->

content/docs/references/ui/component.mdx

@@ -476,7 +476,7 @@ Sort field and direction pair
 | **typeField** | `string` | optional | Field whose value maps to task/summary/milestone |
 | **baselineStartField** | `string` | optional | Baseline (planned) start field |
 | **baselineEndField** | `string` | optional | Baseline (planned) end field |
-| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows) |
+| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows). NO leading or trailing whitespace: the group accessor reads this name off every task verbatim, so a padded spelling drops every task into one ungrouped bucket. |
 | **resourceView** | `boolean` | optional | Render a per-resource workload histogram instead of the timeline |
 | **assigneeField** | `string` | optional | Resource field to bucket load by (resource view) |
 | **effortField** | `string` | optional | Per-task load units (resource view; default 1) |

content/docs/references/ui/view.mdx

@@ -565,7 +565,7 @@ Gallery/card view configuration
 | **typeField** | `string` | optional | Field whose value maps to task/summary/milestone |
 | **baselineStartField** | `string` | optional | Baseline (planned) start field |
 | **baselineEndField** | `string` | optional | Baseline (planned) end field |
-| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows) |
+| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows). NO leading or trailing whitespace: the group accessor reads this name off every task verbatim, so a padded spelling drops every task into one ungrouped bucket. |
 | **resourceView** | `boolean` | optional | Render a per-resource workload histogram instead of the timeline |
 | **assigneeField** | `string` | optional | Resource field to bucket load by (resource view) |
 | **effortField** | `string` | optional | Per-task load units (resource view; default 1) |
@@ -696,7 +696,7 @@ HTTP methods a view data source may request — the subset of `HttpMethod` witho
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **groupByField** | `string` | ✅ | Field to group columns by (usually status/select) |
+| **groupByField** | `string` | ✅ | Field to group columns by (usually status/select). NO leading or trailing whitespace: the board reads this name off every card verbatim, so a padded spelling collapses the whole board into one `Uncategorized` lane. |
 | **summarizeField** | `string` | optional | Field to sum at top of column (e.g. amount) |
 | **titleField** | `string` | optional | Field displayed as the card title. Omit to fall back to the record display name (ADR-0079 resolver chain) |
 | **columns** | `string[]` | ✅ | Fields to show on cards |
@@ -933,7 +933,7 @@ View filter rule
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **groupByField** | `string` | ✅ | Field to group columns by (usually status/select) |
+| **groupByField** | `string` | ✅ | Field to group columns by (usually status/select). NO leading or trailing whitespace: the board reads this name off every card verbatim, so a padded spelling collapses the whole board into one `Uncategorized` lane. |
 | **summarizeField** | `string` | optional | Field to sum at top of column (e.g. amount) |
 | **titleField** | `string` | optional | Field displayed as the card title. Omit to fall back to the record display name (ADR-0079 resolver chain) |
 | **columns** | `string[]` | ✅ | Fields to show on cards |
@@ -962,7 +962,7 @@ View filter rule
 | **typeField** | `string` | optional | Field whose value maps to task/summary/milestone |
 | **baselineStartField** | `string` | optional | Baseline (planned) start field |
 | **baselineEndField** | `string` | optional | Baseline (planned) end field |
-| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows) |
+| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows). NO leading or trailing whitespace: the group accessor reads this name off every task verbatim, so a padded spelling drops every task into one ungrouped bucket. |
 | **resourceView** | `boolean` | optional | Render a per-resource workload histogram instead of the timeline |
 | **assigneeField** | `string` | optional | Resource field to bucket load by (resource view) |
 | **effortField** | `string` | optional | Per-task load units (resource view; default 1) |
@@ -999,7 +999,7 @@ View filter rule
 | **startDateField** | `string` | ✅ | Field for timeline item start date |
 | **endDateField** | `string` | optional | Field for timeline item end date |
 | **titleField** | `string` | ✅ | Field to display as timeline item title |
-| **groupByField** | `string` | optional | Field to group timeline rows |
+| **groupByField** | `string` | optional | Field to group timeline rows. NO leading or trailing whitespace: the renderer reads this name off every row verbatim, so a padded spelling drops every row into one ungrouped band. |
 | **colorField** | `string` | optional | Field to derive each item color from (it names a field, not a color): the option color declared on that field for the record value, else the value itself when it already is a color literal (hex, rgb() or hsl()), else the timeline default marker color |
 | **scale** | `Enum<'hour' \| 'day' \| 'week' \| 'month' \| 'quarter' \| 'year'>` | optional (default: `"week"`) | Default timeline scale |
 
@@ -1331,7 +1331,7 @@ View filter rule
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **groupByField** | `string` | ✅ | Field to group columns by (usually status/select) |
+| **groupByField** | `string` | ✅ | Field to group columns by (usually status/select). NO leading or trailing whitespace: the board reads this name off every card verbatim, so a padded spelling collapses the whole board into one `Uncategorized` lane. |
 | **summarizeField** | `string` | optional | Field to sum at top of column (e.g. amount) |
 | **titleField** | `string` | optional | Field displayed as the card title. Omit to fall back to the record display name (ADR-0079 resolver chain) |
 | **columns** | `string[]` | ✅ | Fields to show on cards |
@@ -1360,7 +1360,7 @@ View filter rule
 | **typeField** | `string` | optional | Field whose value maps to task/summary/milestone |
 | **baselineStartField** | `string` | optional | Baseline (planned) start field |
 | **baselineEndField** | `string` | optional | Baseline (planned) end field |
-| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows) |
+| **groupByField** | `string` | optional | Field to group leaf tasks by (synthesized summary rows). NO leading or trailing whitespace: the group accessor reads this name off every task verbatim, so a padded spelling drops every task into one ungrouped bucket. |
 | **resourceView** | `boolean` | optional | Render a per-resource workload histogram instead of the timeline |
 | **assigneeField** | `string` | optional | Resource field to bucket load by (resource view) |
 | **effortField** | `string` | optional | Per-task load units (resource view; default 1) |
@@ -1397,7 +1397,7 @@ View filter rule
 | **startDateField** | `string` | ✅ | Field for timeline item start date |
 | **endDateField** | `string` | optional | Field for timeline item end date |
 | **titleField** | `string` | ✅ | Field to display as timeline item title |
-| **groupByField** | `string` | optional | Field to group timeline rows |
+| **groupByField** | `string` | optional | Field to group timeline rows. NO leading or trailing whitespace: the renderer reads this name off every row verbatim, so a padded spelling drops every row into one ungrouped band. |
 | **colorField** | `string` | optional | Field to derive each item color from (it names a field, not a color): the option color declared on that field for the record value, else the value itself when it already is a color literal (hex, rgb() or hsl()), else the timeline default marker color |
 | **scale** | `Enum<'hour' \| 'day' \| 'week' \| 'month' \| 'quarter' \| 'year'>` | optional (default: `"week"`) | Default timeline scale |
 
@@ -1649,7 +1649,7 @@ Timeline view configuration
 | **startDateField** | `string` | ✅ | Field for timeline item start date |
 | **endDateField** | `string` | optional | Field for timeline item end date |
 | **titleField** | `string` | ✅ | Field to display as timeline item title |
-| **groupByField** | `string` | optional | Field to group timeline rows |
+| **groupByField** | `string` | optional | Field to group timeline rows. NO leading or trailing whitespace: the renderer reads this name off every row verbatim, so a padded spelling drops every row into one ungrouped band. |
 | **colorField** | `string` | optional | Field to derive each item color from (it names a field, not a color): the option color declared on that field for the record value, else the value itself when it already is a color literal (hex, rgb() or hsl()), else the timeline default marker color |
 | **scale** | `Enum<'hour' \| 'day' \| 'week' \| 'month' \| 'quarter' \| 'year'>` | optional (default: `"week"`) | Default timeline scale |
 

packages/spec/src/migrations/entries/semantic/18.ui-list-view-groupbyfield-padded-refused.ts

@@ -0,0 +1,60 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { SemanticMigration } from '../../types.js';
+
+// The sibling axis of `ui-list-view-grouping-field-padded-refused` (#17360),
+// which scoped this one out by name. Same defect, same refusal, one difference
+// that changes the author's options: `kanban.groupByField` is REQUIRED, so a
+// padded value there cannot be withdrawn by omitting the key.
+export const entry: SemanticMigration = {
+  id: 'ui-list-view-groupbyfield-padded-refused',
+  surface: 'list-view group-by field names — `kanban.groupByField` (`KanbanConfigSchema`, '
+    + 'REQUIRED), `gantt.groupByField` and `timeline.groupByField` (`GanttConfigSchema` / '
+    + '`TimelineConfigSchema`, both optional) — values carrying leading or trailing whitespace',
+  replacement: 'the field name written with no leading and no trailing whitespace — the same '
+    + 'spelling the object declares and the server answers under. A padded value is RE-AUTHORED, '
+    + 'never trimmed on the author\'s behalf: `\' stage\'` becomes `\'stage\'`. The refusal names '
+    + 'the offending spelling verbatim, so the whitespace an author cannot see in an editor is '
+    + 'visible in the message, next to the name to write instead.',
+  reason:
+    '#17499. All three keys were a bare `z.string()`, so a padded group-by name was valid '
+    + 'authored metadata all the way to the renderers. The name is a LOOKUP KEY on every row, '
+    + 'measured in objectui at `dda8f3815`: the kanban board resolves its lane as '
+    + '`laneField = groupByField || groupField || detectStatusField(objectDef)` and buckets cards '
+    + 'by `card[laneField]`; `ObjectGantt`\'s `groupByAccessor` splits the name on `.` and walks '
+    + 'the backing record (`resolvePath(task.data, field)`); the timeline groups its rows the same '
+    + 'way. The server answers under the unpadded name, so every per-row lookup reads `undefined` '
+    + 'and the board collapses into one `Uncategorized` lane — the gantt and the timeline into one '
+    + 'ungrouped bucket — holding every record. That is a silent wrong answer that reads as a true '
+    + 'statement about the data: one giant bucket is indistinguishable from a dataset where the '
+    + 'field genuinely is empty, which is why nothing weaker than a parse refusal is honest here. '
+    + '`packages/lint`\'s `validate-list-view-field-refs` already grades this position `error` for '
+    + 'the same consequence, but it only runs where an app is validated against its object '
+    + 'definitions; the producer accepted the value regardless. ⛔ NOT a `.trim()`: a trimming '
+    + 'schema makes `\' stage\'` and `\'stage\'` silently equivalent, the consumer-tolerance '
+    + 'direction AGENTS.md #0.1 refuses — and on the REQUIRED kanban key the author cannot '
+    + 'withdraw the value by omitting the key, so a normalising producer would be their only '
+    + 'feedback channel and it would say nothing. The narrowing is non-padded ONLY and '
+    + 'deliberately not the snake_case machine-name grammar `/^[a-z_][a-z0-9_]*$/` this package '
+    + 'spells inline for object/field/tool NAMES: a `groupByField` is authored as a field '
+    + 'REFERENCE and a dotted relationship path (`owner.name`) is an in-tree spelling of one. '
+    + 'Ships at once, no deprecation window (2026-08-27 maintainer ruling 「短期不考虑渐进」).',
+  acceptanceCriteria:
+    'Measured against the shipped schemas, not restated from the card. Every stored view whose '
+    + '`kanban.groupByField`, `gantt.groupByField` or `timeline.groupByField` carries leading or '
+    + 'trailing whitespace is refused on its next authoring-path save, with a `custom` issue at '
+    + 'that key\'s own path (`groupByField`, or `kanban.groupByField` when the view is parsed '
+    + 'whole) naming the offending spelling verbatim and the trimmed name to write instead; a '
+    + 'value that is nothing but whitespace is refused with the remedy "Name the field to group '
+    + 'by" rather than a trimmed name, since there is none. Refused: leading, trailing and both; '
+    + 'a tab, a newline and a non-breaking space in those positions; whitespace-only. NOT refused, '
+    + 'on purpose: whitespace INSIDE the name (`\'Group by field\'` parses), and the EMPTY string '
+    + '(unchanged on all three keys, this narrowing covers the silent case only). Nothing is '
+    + 'normalised on the way through — an accepted name arrives byte-identical, `\'owner.name\'` '
+    + 'included — so a consumer proves the migration by re-saving each view and seeing either a '
+    + 'refusal naming the field or a value it can compare byte-for-byte with what it wrote. Every '
+    + '`groupByField` spelling in the repo at the time of the change parses unchanged: 14 distinct '
+    + 'literals harvested across every `.ts` / `.tsx` / `.mdx` / `.json` / `.mjs` outside '
+    + '`node_modules`, zero of them padded, so no fixture had to be rewritten to keep the tree '
+    + 'green.',
+};