@@ -611,7 +611,12 @@ export const CEILINGS = new Map([
   // deleting one from this file. Independently reproducible without running
   // this script:
   //   ceil($(wc -c < skills/objectstack-ui/evals/analytics-inline-vs-dataset.json) / 4) == ceil(4915 / 4)
-  ['skills/objectstack-ui/evals/analytics-inline-vs-dataset.json', 1229],
+  // 1229 -> 1348 (#26295): one eval prompt for the `duration` measure, +119 tokens in the
+  // file's shape. An eval file is fixtures — nothing in it restates anything, so there was
+  // nothing to delete to fund it; the whole addition is raised, pinned AT the measurement.
+  // Maintainer ruling 2026-10-27 (Warren, decision card 「skills 修复卡的教学和 eval 都撞 token 天花板,怎么付?」,
+  // option A tapped at 01:21Z), verbatim and untranslated: 「A:先削重复,余额按实测提高」.
+  ['skills/objectstack-ui/evals/analytics-inline-vs-dataset.json', 1348],
 
   // objectstack-ui `rules/` — the five files the #14296 item 1 split created.
   // Each row is an INITIAL measurement AT its landed count, so every one starts
@@ -621,19 +626,39 @@ export const CEILINGS = new Map([
   // the reassembly exposed (plus three cross-references the move killed) and
   // added nothing but five titles and five pointers,
   // so the package nets -58 (33,957 -> 33,899).
-  ['skills/objectstack-ui/rules/actions.md', 2108],
+  // 2108 -> 2151 (#26295): the 18.2 teaching an AI author of actions was missing — the
+  // `{{ }}` copy holes with their roots and refused shapes, and a flow action's `onSuccess`
+  // reading `${result.output.NAME}` — is +141 tokens. PAID DOWN FIRST by 91 tokens of genuine
+  // deletion in this file (five restatements of this file's own prose: the `openIn`
+  // priority sentence, the print-status clause that pages.md's Print pages carries, the
+  // params-callout remedy that restates the two mechanisms above it, the hooks-parity
+  // clause the paragraph's last sentence already states, one code comment restating the
+  // prose above it), then the row's 7 tokens of headroom absorb 7; the ceiling moves by the
+  // remaining 43 and is pinned AT the measurement — zero headroom. Maintainer ruling 2026-10-27 (Warren, decision card 「skills 修复卡的教学和 eval 都撞 token 天花板,怎么付?」,
+  // option A tapped at 01:21Z), verbatim and untranslated: 「A:先削重复,余额按实测提高」.
+  ['skills/objectstack-ui/rules/actions.md', 2151],
   // 6090 -> 6252 (#19715, card item 4): a 5-line table of contents at the top,
   // anchors to the file's existing headings, nothing else changed. +162 tokens,
   // zero headroom to absorb any of it, ceiling +162. Maintainer ruling
   // 2026-09-22 on decision batch #213 item 1, verbatim and untranslated:
   // 「1 2 4 同意」.
-  ['skills/objectstack-ui/rules/dashboards.md', 6252],
+  // 6252 -> 6239 (#26295): LOWERED. The `duration` measure (+66 tokens, the time between two
+  // `datetime` fields of a record, which the escalation advice sent to a hook-kept number)
+  // is paid in full by deleting 78 tokens of restatement — the example's four-line comment
+  // that restated the Dataset-Bound Widgets section — so the file nets -12 and the ceiling
+  // follows it down to the new measurement, the ratchet's ordinary direction.
+  ['skills/objectstack-ui/rules/dashboards.md', 6239],
   // 3011 -> 3141 (#19715, card item 4): a 5-line table of contents at the top,
   // anchors to the file's existing headings, nothing else changed. +132 tokens,
   // of which the row's 2 tokens of headroom absorb 2; the CEILING moves 130.
   // Maintainer ruling 2026-09-22 on decision batch #213 item 1, verbatim and
   // untranslated: 「1 2 4 同意」.
-  ['skills/objectstack-ui/rules/list-views.md', 3141],
+  // 3141 -> 3129 (#26295): LOWERED. List-view `grouping.fields[]` and `orderBy` (+127 tokens;
+  // grouping was untaught, 0 hits) are paid in full by deleting 131 tokens of restatement —
+  // the paragraph restating the allowed-set table above it, and the related-record search
+  // prescription that objectstack-data → Search Fields carries whole — so the file nets -4
+  // and the ceiling follows it down to the new measurement.
+  ['skills/objectstack-ui/rules/list-views.md', 3129],
   ['skills/objectstack-ui/rules/navigation.md', 2273],
   // 5501 -> 5692 (#19715, card item 4): a 5-line table of contents at the top,
   // anchors to the file's existing headings, nothing else changed. +191 tokens,
@@ -691,7 +716,11 @@ export const CEILINGS = new Map([
   ['skills/objectstack-i18n/evals/bundles-locales-coverage.json', 1004],
   ['skills/objectstack-platform/evals/config-plugins-ops.json', 1211],
   ['skills/objectstack-query/evals/filters-pagination-search.json', 955],
-  ['skills/objectstack-ui/evals/views-apps-actions-pages.json', 1505],
+  // 1505 -> 1789 (#26295): two eval prompts — list grouping with `orderBy`, and the copy hole
+  // + `onSuccess` pair — +284 tokens in the file's shape; fixtures, nothing to delete, the
+  // whole addition raised and pinned AT the measurement. Maintainer ruling 2026-10-27 (Warren, decision card 「skills 修复卡的教学和 eval 都撞 token 天花板,怎么付?」,
+  // option A tapped at 01:21Z), verbatim and untranslated: 「A:先削重复,余额按实测提高」.
+  ['skills/objectstack-ui/evals/views-apps-actions-pages.json', 1789],
   ['skills/objectstack-upgrade/evals/protocol-major-upgrade.json', 1033],
 
   // the remaining skills' eval notes
 
@@ -72,6 +72,16 @@
         "must_contain": ["$contains"],
         "must_not_contain": ["field: 'tags'", "groupBy: 'tags'", "sql: 'tags'"]
       }
+    },
+    {
+      "id": 8,
+      "prompt": "Add a KPI of the average days from an opportunity's created_at to its closed_at (both datetime). Emit the metadata.",
+      "expected_output": "A dataset measure `{ aggregate: 'avg', duration: { from: 'created_at', to: 'closed_at', unit: 'days' } }`; no hook-kept stored number.",
+      "files": [],
+      "assertions": {
+        "must_contain": ["duration", "unit: 'days'"],
+        "must_not_contain": ["beforeUpdate"]
+      }
     }
   ]
 }
@@ -60,6 +60,26 @@
         "must_contain": ["type: 'wizard'", "inlineEdit", "formViews", "master_detail"],
         "must_not_contain": ["type: 'screen'"]
       }
+    },
+    {
+      "id": 7,
+      "prompt": "Group the opportunity list by stage in pipeline order, and the forecast list by period_label, newest first (period_start is a date).",
+      "expected_output": "`grouping: { fields: [{ field: 'stage' }] }`: a select keeps its option order, and `orderBy` refuses a select. Forecast: `{ field: 'period_label', orderBy: 'period_start', order: 'desc' }`.",
+      "files": [],
+      "assertions": {
+        "must_contain": ["grouping", "orderBy: 'period_start'"],
+        "must_not_contain": ["orderBy: 'stage'"]
+      }
+    },
+    {
+      "id": 8,
+      "prompt": "Make the Reassign Lead toast read 'Lead NAME reassigned'; after Convert's lead_conversion flow completes, open the opportunity it created.",
+      "expected_output": "`successMessage: 'Lead {{ record.name }} reassigned'` (`${record.name}` fails `os validate`); Convert gets `onSuccess: { navigate }` ending `${result.output.opportunity_id}`, an `isOutput` flow variable.",
+      "files": [],
+      "assertions": {
+        "must_contain": ["{{", "onSuccess", "result.output"],
+        "must_not_contain": ["${record.name}"]
+      }
     }
   ]
 }
@@ -18,7 +18,8 @@
 - `visible` — CEL predicate (prefer the `P\`...\`` tagged template); when false the action is **hidden**.
 - `disabled` — `boolean` **or** a CEL predicate; when true the action **shows but greys out**. Use this (not `visible`) when the action should stay discoverable but locked in the current state.
 - `confirmText` — set for any destructive or irreversible operation.
-- `successMessage` / `errorMessage` — author-controlled toast copy on success / failure. Always set `successMessage` for non-obvious outcomes; without it the UI shows a generic "Action completed" toast.
+- `successMessage` / `errorMessage` — toast copy on success / failure. Always set `successMessage` for non-obvious outcomes; without it the UI shows a generic "Action completed" toast.
+- Copy holes are `{{ }}`: `confirmText` reads `record`, `successMessage` `record` and `result` (the handler's answer); `errorMessage` takes none. A `bulkActionDefs` entry's `confirmText` reads `{{ count }}` and its params by bare name (`{{ tier }}`). `${record.name}`, `{name}`, logic in a hole and a blank sentence fail `os validate`.
 - `undoable: true` — an **Undo** in the success toast (and `Ctrl+Z`). Snapshot: runtime on `operation: 'update'`, console on `type: 'api'`; else refused.
 
 Predicates are **bare CEL** — `record.status == "converted"`, evaluated against
@@ -42,14 +43,14 @@ export const ReassignLeadAction = defineAction({
   disabled: P`record.status == "converted"`,
   params: [{ field: 'assigned_to', required: true }],
   undoable: true,                 // success toast offers Undo; Ctrl+Z works too
-  successMessage: 'Lead reassigned.',
+  successMessage: 'Lead {{ record.name }} reassigned.',
   errorMessage: "Couldn't reassign this lead — try again.",
 });
 ```
 
 ## Examples
 
-**Flow-typed action** (delegates to a screen flow):
+**Flow-typed action** (`onSuccess` hops once the run completes, not when it pauses at a screen; its URL template reads an `isOutput` variable as `${result.output.NAME}`):
 
 <!-- os:check -->
 ```typescript
@@ -67,6 +68,7 @@ export const ConvertLeadAction = defineAction({
   visible: P`record.status == "qualified" && record.is_converted == false`,
   confirmText: 'Are you sure you want to convert this lead?',
   successMessage: 'Lead converted successfully!',
+  onSuccess: { navigate: '/apps/crm/opportunity/record/${result.output.opportunity_id}' },
   refreshAfter: true,
 });
 ```
@@ -114,8 +116,7 @@ A server-side action `body` (and a registered function `handler`) receives a
 `recordId` is in scope), `api` (scoped cross-object CRUD), and the caller
 identity. Read the caller's active organization under the **blessed**
 `organizationId` name — the same value as the `organization_id` column and
-`current_user.organizationId` in RLS, so it matches hooks and seed data with
-zero relearning:
+`current_user.organizationId` in RLS:
 
 ```typescript
 // ✅ Blessed — identical to the hook surface (ctx.user / ctx.session)
@@ -143,8 +144,7 @@ When you have a **static** `target` URL (relative or absolute) you just want
 opened in a new tab, set `openIn: 'new-tab'` on a `type: 'url'` action. No
 handler, no synchronous pre-open. `openIn: 'self'` forces in-place navigation;
 omit it and external/absolute URLs open in a new tab while relative URLs
-navigate in place. objectui's `ActionRunner.executeUrl` reads `openIn` with
-priority over the legacy heuristic.
+navigate in place.
 
 <!-- os:check -->
 ```typescript
@@ -179,21 +179,18 @@ export const OpenInvoicePdfAction = defineAction({
   type: 'script',
   target: 'open_invoice_pdf',   // registered handler; skipped while newTabUrl is set
   opensInNewTab: true,
-  newTabUrl: '/api/v1/invoice/{recordId}/pdf',   // zero-roundtrip; endpoint self-auths
+  newTabUrl: '/api/v1/invoice/{recordId}/pdf',
   locations: ['record_header'],
 });
 ```
 
-> A printable document (an invoice) is a page that declares `print` — [Print pages](./pages.md#print-pages):
-> validated today, rendered once the console's print rendering ships.
+> A printable document (an invoice) is a page that declares `print` — [Print pages](./pages.md#print-pages).
 
 > ⚠️ **Never express new-tab behavior via `params`.** `params` is exclusively
 > `ActionParam[]` for collecting **user input**. Writing an object form like
 > `params: { newTab: true }` fails the zod build outright; the array form
 > `params: [{ name: 'newTab', type: 'checkbox' }]` *builds* but mis-renders as a
-> user-facing checkbox in the param-collection dialog. Use `openIn` (static) or
-> `opensInNewTab`/`newTabUrl` (async) instead — these are static execution
-> options, not inputs.
+> user-facing checkbox in the param-collection dialog. Use one of the two mechanisms above.
 
 ## Action Parameter Patterns
 
 
@@ -67,7 +67,7 @@ escalate to. Decide on **expressibility**; reuse/governance is Level B.
 |:--|:--|
 | one base object + **to-one** joins (`include`, ≤3 hops) | a join that **changes grain** / a **to-many** rollup onto the parent |
 | 0..N dimensions; date-bucket `day/week/month/quarter/year` | a **computed dimension** / CASE bucket / numeric bin |
-| measures `count/sum/avg/min/max/count_distinct` | list aggregation (collect-into-array / concatenate — retired in protocol 17, no spelling exists) |
+| measures `count/sum/avg/min/max/count_distinct`, `duration` | list aggregation (collect-into-array / concatenate — retired in protocol 17, no spelling exists) |
 | **derived measures** — `ratio/sum/difference/product` of other measures | scalar math on raw fields (`amount*0.8`), aggregate-of-aggregate |
 | WHERE (`$and/$or/$not` on the base object) + measure-scoped filters | **HAVING** (filtering the aggregate result) |
 | `compareTo` (previous period/year) + `totals` (matrix subtotals) | **window** (rank, running total, lag/lead, %-of-total); **union**; reshaping params |
@@ -88,15 +88,18 @@ Standardized answers to the recurring ambiguous cases:
 - **To-one enrichment** ("revenue by `account.industry`") keeps grain — `account`
   in `include`, `account.industry` as a dimension.
 - **Computed column.** Format/currency → the measure's `format`/`currency`;
-  arithmetic over measures → a **derived measure**; CASE / bins /
+  arithmetic over measures → a **derived measure**; time between two
+  `datetime` fields of a record → a **`duration` measure**, not a hook-kept
+  number (`{ name: 'avg_days_to_close', aggregate: 'avg', duration: { from:
+  'created_at', to: 'closed_at', unit: 'days' } }`); CASE / bins /
   `revenue*0.8` / computed dimensions → **not** a dataset.
 - **Total over a computed value.** `sum`/`avg`/`min`/`max` need a STORED numeric
   or boolean field (`percent` not under `sum`; `min`/`max` also dates); a `formula`
   has no column: refused whatever its `returnType` says. Store the number
   (user-entered, a `summary` rollup, or hook-kept) or title the widget the `count`
   it is. Leave days: `sum` over the `formula` `days_requested` (`end - start`) is
-  refused ⇒ a stored `number` `days_count` a `beforeInsert`/`beforeUpdate` hook
-  writes, then `{ name: 'days_sum', aggregate: 'sum', field: 'days_count' }`.
+  refused (`date` fields: no `duration`) ⇒ a stored `number` `days_count` a
+  `beforeInsert`/`beforeUpdate` hook writes, then `{ name: 'days_sum', aggregate: 'sum', field: 'days_count' }`.
 - **Breakdown by a multi-value field.** `multiselect`/`checkboxes`/`tags` and
   any `multiple: true` field is refused as a dataset or cube dimension and as
   `groupBy` (`INVALID_FIELD`; no per-member buckets). One widget per member,
@@ -168,10 +171,6 @@ export const SalesDashboard: Dashboard = {
       optionsFrom: { object: 'user', valueField: 'id', labelField: 'name' } },
   ],
 
-  // ADR-0021: widgets bind a semantic `dataset` and select dimensions/measures
-  // BY NAME (the `opportunity_metrics` / `order_metrics` datasets define the base
-  // object, measures, and date dimensions — see Guides → Analytics Datasets). The
-  // widget `filter` is the presentation-scope runtimeFilter.
   widgets: [
     {
       id: 'total_pipeline_value', type: 'metric',
 
@@ -1,7 +1,7 @@
 # List, Kanban & Gantt Views
 
 - [Configuring a List View](#configuring-a-list-view) · [The `defineView` container](#the-defineview-container-viewts-file-shape) · [Data Source](#data-source-data)
-- [Columns](#columns) · [Column Features](#column-features) · [Filtering](#filtering) · [Sorting](#sorting)
+- [Columns](#columns) · [Column Features](#column-features) · [Filtering](#filtering) · [Sorting](#sorting) · [Grouping](#grouping)
 - [End-User Quick Filters](#end-user-quick-filters-userfilters-adr-0047) · [Toolbar Search](#toolbar-search-searchablefields-adr-0061)
 - [Configuring Kanban Views](#configuring-kanban-views)
 - [Configuring Gantt Views](#configuring-gantt-views)
@@ -190,10 +190,7 @@ export const CaseViews = defineView({
 | declares `searchableFields` | **that list, verbatim** — whatever the field types are |
 | declares nothing | the auto-default: the name field + the text-like columns (`text` / `email` / `phone` / `url` / `autonumber` / `textarea` / `markdown` / `select` / `status`) |
 
-Field **type** therefore decides only in the second row: where the object
-declares the set, a lookup in it is scanned and a `text` column outside it is
-refused. Judge every entry against the object's allowed set, never the type
-list. Modelling side: **objectstack-data → Search Fields**. Query side
+Modelling side: **objectstack-data → Search Fields**. Query side
 (`search.fields` over the API): **objectstack-query → Full-Text Search**.
 
 #### ⛔ One bad entry 400s EVERY search on that list
@@ -233,12 +230,8 @@ export const AuditViews = defineView({
 });
 ```
 
-**Searching by a related record's title:** never reach for a dotted path. The
-search axis resolves no traversal, so `account_id.name` is refused rather than
-silently dropped. Mirror the parent's title into a **stored** field on this
-object and narrow to that. The prescription — the mirror field, the two hooks
-that maintain it, and why a `formula` field cannot be the mirror — lives in
-**objectstack-data → Search Fields (`searchableFields`)**.
+**Searching by a related record's title:** mirror it into a **stored** field
+and narrow to that — **objectstack-data → Search Fields (`searchableFields`)**.
 
 ### Sorting
 
@@ -250,6 +243,21 @@ sort: [
 ]
 ```
 
+### Grouping
+
+`grouping.fields[]` nests levels, outermost first. A `select` level keeps its
+option order (declare stages in pipeline order); others sort by label.
+`orderBy` orders a level's groups by a number, date or boolean field of the
+same object instead — text or a select is refused
+(`list-view-group-order-unorderable`):
+
+```typescript
+grouping: { fields: [
+  { field: 'stage' },
+  { field: 'period_label', orderBy: 'period_start', order: 'desc' },  // newest first
+] },
+```
+
 ---
 
 ## Configuring Kanban Views
Original file line number	Diff line number	Diff line change
`@@ -72,6 +72,16 @@`
`72`	`72`	`"must_contain": ["$contains"],`
`73`	`73`	`"must_not_contain": ["field: 'tags'", "groupBy: 'tags'", "sql: 'tags'"]`
`74`	`74`	`}`
	`75`	`+ },`
	`76`	`+ {`
	`77`	`+ "id": 8,`
	`78`	`+ "prompt": "Add a KPI of the average days from an opportunity's created_at to its closed_at (both datetime). Emit the metadata.",`
	`79`	+ "expected_output": "A dataset measure `{ aggregate: 'avg', duration: { from: 'created_at', to: 'closed_at', unit: 'days' } }`; no hook-kept stored number.",
	`80`	`+ "files": [],`
	`81`	`+ "assertions": {`
	`82`	`+ "must_contain": ["duration", "unit: 'days'"],`
	`83`	`+ "must_not_contain": ["beforeUpdate"]`
	`84`	`+ }`
`75`	`85`	`}`
`76`	`86`	`]`
`77`	`87`	`}`