@@ -0,0 +1,44 @@
+---
+'@objectstack/spec': minor
+---
+
+**BREAKING for authored metadata** — `undoable: true` on a registered `action` is now legal only on a shape some runtime actually fulfils, and refused at parse time everywhere else.
+
+Clause-②: yes
+
+The accept set narrows. `undoable` was a plain optional boolean that no refinement read, so it parsed clean on every action shape while only two of them ever produced an Undo — the declared-but-inert case the spec refuses at author time (ADR-0078).
+
+**The two fulfilled shapes, and which runtime fulfils each**
+
+| shape | who takes the snapshot |
+| --- | --- |
+| `operation: 'update'` (with a `patch`) | the framework runtime — the prior value of every field in the merged write bag, `patch` UNDER the collected `params` |
+| `type: 'api'` | the pinned console — it builds the undo envelope from `undoable` alone |
+
+Both stay accepted, byte-identically. Naming the console in the contract is deliberate: the spec is the contract for every runtime including the console, and a closed table of fulfillable combinations is what the declared-is-delivered rule asks for.
+
+**What is refused**
+
+`undoable: true` on `type: 'script'` (the default route) or `type: 'url'`, and on the dormant `type: 'flow'` / `'modal'` / `'form'`, in each case without `operation: 'update'`. Nothing reads the flag on those shapes, so it promised an Undo that never appeared.
+
+```
+✗ undoable: `undoable: true` has no runtime that can fulfil it on this action. An Undo is
+  captured on exactly two shapes: `operation: 'update'`, where the framework runtime snapshots
+  the prior value of every field the write bag touches, and `type: 'api'`, which the console
+  snapshots. …
+```
+
+**⛔ What is deliberately NOT refused, because it was measured wrong.** Requiring `operation: 'update'` — the obvious repair — would refuse the published `ReassignLeadAction` skill example (`type: 'api'` + `undoable: true`, no `operation`) at import time, since `defineAction` IS `ActionSchema.parse`, and every console api action with undo along with it. The console's two readers gate the undo envelope on `action.undoable` alone with zero reads of `action.operation`, and those same two files are the entire recorded evidence for this package's own liveness verdict `action/undoable: live`. `undoable` absent or `false` is untouched on every type, and the rule lives on `ActionSchema`'s refine chain alone — an inline action is not a registered action.
+
+### Migration — FROM → TO
+
+| You wrote | Write instead |
+| --- | --- |
+| `{ type: 'script', body, undoable: true }` | `{ operation: 'update', patch: { … }, undoable: true }` if the action is a single-record field write, or drop `undoable` and keep the handler |
+| `{ type: 'url' \| 'flow' \| 'modal' \| 'form', undoable: true }` | the same action without `undoable` — those routes never had a capture, so behaviour is unchanged |
+
+⛔ Not mechanically convertible, so this ships as an ADR-0087 D3 structured TODO rather than a D2 conversion: which of the two fulfilled shapes an author meant is an intent no artifact records — a `script` action with an inline handler and an api action calling an endpoint are different dispatches, not two spellings of one — and dropping the flag automatically would remove an Undo the author asked for.
+
+<!-- adr-0087: registered ui-action-undoable-unfulfillable-refused -->
+
+**Published surface.** No export is added, removed or renamed; `ActionType` still carries all six types. The `undoable` `.describe()` and the comment above it are corrected in the same change: both claimed that an action with no `operation` has nothing anchoring the capture, which is false against the pinned console.
@@ -461,7 +461,7 @@ const result = ApiMethod.parse(data);
 | **successMessage** | `string \| Record<string, string>` | optional | Success message to show after execution |
 | **errorMessage** | `string \| Record<string, string>` | optional | Error message to show when the action fails (overrides the raw error). |
 | **refreshAfter** | `boolean` | optional (default: `false`) | Refresh view after execution |
-| **undoable** | `boolean` | optional | Offer an Undo affordance after this single-record update action succeeds. `operation: 'update'` is the one declared operation and the declared form of that action: what the undo captures is the prior value of EVERY field the action writes — the merged write bag, `patch` UNDER the collected `params`, not `patch` alone. An action with no `operation` declares no write set, so nothing anchors the capture there. |
+| **undoable** | `boolean` | optional | Offer an Undo affordance after this single-record update action succeeds. `operation: 'update'` is the one declared operation and the declared form of that action: what the undo captures is the prior value of EVERY field the action writes — the merged write bag, `patch` UNDER the collected `params`, not `patch` alone. An action with no `operation` declares no write set here, but `type: 'api'` is fulfilled by the console, which builds the undo envelope from `undoable` alone. Those two shapes — `operation: 'update'` and `type: 'api'` — are the whole fulfillable set; on a registered action `undoable` beside any other shape is refused, because nothing would anchor the capture. |
 | **resultDialog** | `{ title?: string \| Record<string, string>; description?: string \| Record<string, string>; acknowledge?: string \| Record<string, string>; format?: Enum<'qrcode' \| 'code-list' \| 'secret' \| 'text' \| 'json'>; … }` | optional | Render API response in a one-shot reveal dialog (suppresses successMessage when set). |
 | **visible** | `boolean \| string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source: string; ast?: any; meta?: object }` | optional | Visibility predicate — `true`/`false` literal, CEL string, or `{dialect, source}` envelope. The action is offered when it evaluates TRUE. Omit = always visible. |
 | **requiresFeature** | `Enum<'twoFactor' \| 'organization' \| 'multiOrgEnabled' \| 'degradedTenancy' \| …>` | optional | Public auth feature flag gating this action; lowered into `visible` at parse time. |
 
@@ -330,7 +330,7 @@ const result = MetadataBulkResultSchema.parse(data);
 | **successMessage** | `string \| Record<string, string>` | optional | Success message to show after execution |
 | **errorMessage** | `string \| Record<string, string>` | optional | Error message to show when the action fails (overrides the raw error). |
 | **refreshAfter** | `boolean` | optional (default: `false`) | Refresh view after execution |
-| **undoable** | `boolean` | optional | Offer an Undo affordance after this single-record update action succeeds. `operation: 'update'` is the one declared operation and the declared form of that action: what the undo captures is the prior value of EVERY field the action writes — the merged write bag, `patch` UNDER the collected `params`, not `patch` alone. An action with no `operation` declares no write set, so nothing anchors the capture there. |
+| **undoable** | `boolean` | optional | Offer an Undo affordance after this single-record update action succeeds. `operation: 'update'` is the one declared operation and the declared form of that action: what the undo captures is the prior value of EVERY field the action writes — the merged write bag, `patch` UNDER the collected `params`, not `patch` alone. An action with no `operation` declares no write set here, but `type: 'api'` is fulfilled by the console, which builds the undo envelope from `undoable` alone. Those two shapes — `operation: 'update'` and `type: 'api'` — are the whole fulfillable set; on a registered action `undoable` beside any other shape is refused, because nothing would anchor the capture. |
 | **resultDialog** | `{ title?: string \| Record<string, string>; description?: string \| Record<string, string>; acknowledge?: string \| Record<string, string>; format?: Enum<'qrcode' \| 'code-list' \| 'secret' \| 'text' \| 'json'>; … }` | optional | Render API response in a one-shot reveal dialog (suppresses successMessage when set). |
 | **visible** | `boolean \| string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source: string; ast?: any; meta?: object }` | optional | Visibility predicate — `true`/`false` literal, CEL string, or `{dialect, source}` envelope. The action is offered when it evaluates TRUE. Omit = always visible. |
 | **requiresFeature** | `Enum<'twoFactor' \| 'organization' \| 'multiOrgEnabled' \| 'degradedTenancy' \| …>` | optional | Public auth feature flag gating this action; lowered into `visible` at parse time. |
 
@@ -49,7 +49,7 @@ const result = ActionSchema.parse(data);
 | **successMessage** | `string \| Record<string, string>` | optional | Success message to show after execution |
 | **errorMessage** | `string \| Record<string, string>` | optional | Error message to show when the action fails (overrides the raw error). |
 | **refreshAfter** | `boolean` | optional (default: `false`) | Refresh view after execution |
-| **undoable** | `boolean` | optional | Offer an Undo affordance after this single-record update action succeeds. `operation: 'update'` is the one declared operation and the declared form of that action: what the undo captures is the prior value of EVERY field the action writes — the merged write bag, `patch` UNDER the collected `params`, not `patch` alone. An action with no `operation` declares no write set, so nothing anchors the capture there. |
+| **undoable** | `boolean` | optional | Offer an Undo affordance after this single-record update action succeeds. `operation: 'update'` is the one declared operation and the declared form of that action: what the undo captures is the prior value of EVERY field the action writes — the merged write bag, `patch` UNDER the collected `params`, not `patch` alone. An action with no `operation` declares no write set here, but `type: 'api'` is fulfilled by the console, which builds the undo envelope from `undoable` alone. Those two shapes — `operation: 'update'` and `type: 'api'` — are the whole fulfillable set; on a registered action `undoable` beside any other shape is refused, because nothing would anchor the capture. |
 | **resultDialog** | `{ title?: string \| Record<string, string>; description?: string \| Record<string, string>; acknowledge?: string \| Record<string, string>; format?: Enum<'qrcode' \| 'code-list' \| 'secret' \| 'text' \| 'json'>; … }` | optional | Render API response in a one-shot reveal dialog (suppresses successMessage when set). |
 | **visible** | `boolean \| string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source: string; ast?: any; meta?: object }` | optional | Visibility predicate — `true`/`false` literal, CEL string, or `{dialect, source}` envelope. The action is offered when it evaluates TRUE. Omit = always visible. |
 | **requiresFeature** | `Enum<'twoFactor' \| 'organization' \| 'multiOrgEnabled' \| 'degradedTenancy' \| 'oidcProvider' \| 'sso' \| 'ssoEnforced' \| 'deviceAuthorization' \| 'admin' \| 'phoneNumber' \| 'phoneNumberOtp'>` | optional | Public auth feature flag gating this action; lowered into `visible` at parse time. |
 
@@ -0,0 +1,43 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { SemanticMigration } from '../../types.js';
+
+export const entry: SemanticMigration = {
+  id: 'ui-action-undoable-unfulfillable-refused',
+  surface: '`action` documents declaring `undoable: true` on a shape no runtime fulfils — '
+    + "`type: 'script'` (the default route) and `type: 'url'`, plus the dormant "
+    + "`type: 'flow'` / `'modal'` / `'form'`, in each case WITHOUT `operation: 'update'`",
+  replacement: "either of the two fulfilled shapes — `operation: 'update'` with a `patch`, "
+    + 'where the framework runtime snapshots the prior value of every field in the merged '
+    + "write bag, or `type: 'api'`, where the pinned console builds the undo envelope — or "
+    + 'no `undoable` at all. ⛔ NOT mechanically convertible: which of the two the author '
+    + 'meant is an intent no artifact records (a `script` action with an inline handler and '
+    + 'an api action calling an endpoint are different dispatches, not two spellings of '
+    + 'one), and dropping the flag silently would remove an Undo the author asked for. The '
+    + 'refusal names both shapes and the drop, and the author chooses',
+  reason:
+    'The key was a plain optional boolean read by no refinement, so every combination '
+    + 'parsed clean while only two of them ever produced an Undo — the declared-but-inert '
+    + 'shape ADR-0078 refuses at author time. ⚠️ The obvious repair, requiring '
+    + "`operation: 'update'`, was MEASURED WRONG and is deliberately not what this entry "
+    + "records: the pinned console's two readers gate the undo envelope on "
+    + '`action.undoable` alone with zero reads of `action.operation`, and those same two '
+    + "files are the entire recorded evidence for this package's own liveness verdict "
+    + '`action/undoable: live`. A blanket requirement would therefore have refused the '
+    + 'published `ReassignLeadAction` skill example (`type: \'api\'` + `undoable: true`, no '
+    + '`operation`) at import time, since `defineAction` IS `ActionSchema.parse`, and every '
+    + 'console api action with undo along with it. So the accepted set is closed to the '
+    + 'two shapes some runtime fulfils rather than to the one the framework runtime '
+    + 'fulfils. Stating "`type: \'api\'` is fulfilled by the console" in the contract is '
+    + 'the point, not a leak: the spec is the contract for every runtime including the '
+    + 'console, and a closed table of fulfillable combinations is what the '
+    + 'declared-is-delivered rule asks for.',
+  acceptanceCriteria:
+    "Every `action` document declaring `undoable: true` carries `operation: 'update'` or "
+    + "`type: 'api'`. Both fulfilled shapes parse byte-identically to before — the "
+    + 'published `ReassignLeadAction` example included — and an action with `undoable` '
+    + 'absent or `false` is untouched on every type. An action declaring `undoable: true` '
+    + 'on any other shape is refused with a per-key issue at `undoable` whose message names '
+    + 'both fulfilling shapes and the runtime that fulfils each; the author adds the shape '
+    + 'they meant or drops the flag.',
+};
@@ -12410,6 +12410,45 @@ const step18: MigrationStep = {
         + 'and must be verified as such: nothing ever parsed or read these shapes, so removing '
         + 'them removes no behaviour.',
     },
+    {
+      id: 'ui-action-undoable-unfulfillable-refused',
+      surface: '`action` documents declaring `undoable: true` on a shape no runtime fulfils — '
+        + "`type: 'script'` (the default route) and `type: 'url'`, plus the dormant "
+        + "`type: 'flow'` / `'modal'` / `'form'`, in each case WITHOUT `operation: 'update'`",
+      replacement: "either of the two fulfilled shapes — `operation: 'update'` with a `patch`, "
+        + 'where the framework runtime snapshots the prior value of every field in the merged '
+        + "write bag, or `type: 'api'`, where the pinned console builds the undo envelope — or "
+        + 'no `undoable` at all. ⛔ NOT mechanically convertible: which of the two the author '
+        + 'meant is an intent no artifact records (a `script` action with an inline handler and '
+        + 'an api action calling an endpoint are different dispatches, not two spellings of '
+        + 'one), and dropping the flag silently would remove an Undo the author asked for. The '
+        + 'refusal names both shapes and the drop, and the author chooses',
+      reason:
+        'The key was a plain optional boolean read by no refinement, so every combination '
+        + 'parsed clean while only two of them ever produced an Undo — the declared-but-inert '
+        + 'shape ADR-0078 refuses at author time. ⚠️ The obvious repair, requiring '
+        + "`operation: 'update'`, was MEASURED WRONG and is deliberately not what this entry "
+        + "records: the pinned console's two readers gate the undo envelope on "
+        + '`action.undoable` alone with zero reads of `action.operation`, and those same two '
+        + "files are the entire recorded evidence for this package's own liveness verdict "
+        + '`action/undoable: live`. A blanket requirement would therefore have refused the '
+        + 'published `ReassignLeadAction` skill example (`type: \'api\'` + `undoable: true`, no '
+        + '`operation`) at import time, since `defineAction` IS `ActionSchema.parse`, and every '
+        + 'console api action with undo along with it. So the accepted set is closed to the '
+        + 'two shapes some runtime fulfils rather than to the one the framework runtime '
+        + 'fulfils. Stating "`type: \'api\'` is fulfilled by the console" in the contract is '
+        + 'the point, not a leak: the spec is the contract for every runtime including the '
+        + 'console, and a closed table of fulfillable combinations is what the '
+        + 'declared-is-delivered rule asks for.',
+      acceptanceCriteria:
+        "Every `action` document declaring `undoable: true` carries `operation: 'update'` or "
+        + "`type: 'api'`. Both fulfilled shapes parse byte-identically to before — the "
+        + 'published `ReassignLeadAction` example included — and an action with `undoable` '
+        + 'absent or `false` is untouched on every type. An action declaring `undoable: true` '
+        + 'on any other shape is refused with a per-key issue at `undoable` whose message names '
+        + 'both fulfilling shapes and the runtime that fulfils each; the author adds the shape '
+        + 'they meant or drops the flag.',
+    },
     // The one key this close DECLARES rather than refuses is `dependsOn`, so an author
     // who wrote it keeps working and now has a contract saying so. Everything else
     // undeclared becomes a parse error. Registered as a structured TODO (ADR-0087 D3)