objectstack-ai · os-project-manager · Sep 5, 2026 · Sep 5, 2026 · Sep 5, 2026 · Sep 5, 2026
diff --git a/.changeset/typed-expression-envelope-dialect.md b/.changeset/typed-expression-envelope-dialect.md
@@ -0,0 +1,63 @@
+---
+"@objectstack/spec": minor
+---
+
+feat(spec)!: a typed expression slot fixes its dialect on the envelope arm too, and refuses a blank string (#15028, #15035)
+
+<!-- adr-0087: not-required (no-migration-prescription) No authorable key is renamed, retired or re-typed: every one of the twelve cron- and template-typed keys still takes the bare string and the same-dialect envelope it took before. The two newly refused shapes — an envelope naming a foreign dialect, and a blank string — were measured against every author value in this repo, the examples, the docs, the skills and the objectui pin (32 cron and 14 template values; #15035 census comment 5552934813): zero real authors write either, so the ledger has nothing to rewrite and this changeset carries no rewrite instruction. The remedy is authoring intent: declare the slot's own dialect, or write the bare string. -->
+
+**BREAKING** accept-set narrowing on the twelve authorable keys typed
+`CronExpressionInputSchema` (`system/CronSchedule:expression`,
+`ai/KnowledgeRefreshPolicy:cron`, `api/ScheduledExport` and
+`api/ScheduleExportRequest` `schedule.cronExpression`,
+`automation/ScheduleState:cronExpression`, `integration/DataSyncConfig:schedule`,
+`system/CacheWarmup:schedule`, `system/BackupConfig:schedule`,
+`system/DisasterRecoveryPlan` `testing.schedule`) and
+`TemplateExpressionInputSchema` (`ai/PromptTemplate:system`,
+`ai/PromptTemplate:user`, `data/Object:titleFormat`). Shipped as `minor` under
+the repo's launch-window convention for breaking changes. Measured cost: zero
+— of the 46 author values probed across the repo, the examples, the docs, the
+skills and the objectui pin, every one is a bare string or a same-dialect
+envelope.
+
+**What changes** (`packages/spec/src/shared/expression.zod.ts`):
+
+- The envelope arm of each typed schema is `ExpressionSchema` narrowed to that
+  one dialect literal. A cron-typed slot accepts a bare string or
+  `{ dialect: 'cron', source }` only; a template-typed slot likewise for
+  `template`. An envelope naming any other dialect — `cel` or `template` on a
+  cron slot, `cel` or `cron` on a template slot, or the retired `js` — is
+  refused with ONE `invalid_union` at the slot whose message is the slot's
+  dialect-only sentence (`TYPED_EXPRESSION_DIALECT_ONLY[dialect]`, exported).
+  Before, the arm was the unrestricted `ExpressionSchema`, so a cron slot
+  parsed a `cel` envelope green and whatever read it received an expression it
+  could not schedule — a copy-paste artifact of the untyped schema, never a
+  decision.
+- The bare-string arm refuses a blank string — empty or whitespace-only, the
+  notion of blank `EvaluatedExpressionSchema` already applies (`source.trim()`)
+  — with ONE `invalid_union` at the slot whose message is the slot's
+  source-required sentence (`TYPED_EXPRESSION_SOURCE_REQUIRED[dialect]`,
+  exported). Before, `.min(1)` did not trim, so `'   '` normalized to
+  `{ dialect: 'cron', source: '   ' }` on every typed slot.
+- The author type narrows with it: `CronExpressionInput` /
+  `TemplateExpressionInput` no longer admit a foreign-dialect envelope, and the
+  published JSON Schema and the generated reference page declare the envelope's
+  `dialect` as that one literal. `TypedExpressionDialect` names the pair.
+
+**What does NOT change.** No cron syntax is judged at parse time; `croner`
+judges it where a schedule is wired (`CronSchedule.expression`, the one cron
+slot with a reader); no grammar is restated in spec. `'not a cron'` still
+normalizes to `{ dialect: 'cron', source: 'not a cron' }`, deliberately: the
+repo's two cron grammars already disagree on 5 of 32 probed patterns, and a
+restatement would be a third. `ExpressionInputSchema` and `ExpressionSchema`
+are untouched — the untyped envelope still takes every declared dialect, and an
+envelope with neither `source` nor `ast` is refused exactly as before.
+
+```ts
+// a cron-typed slot, e.g. defineStack({ jobs: [{ schedule: { type: 'cron', expression } }] })
+expression: '0 9 * * 1-5'                              // accepted, normalized to { dialect: 'cron', source }
+expression: { dialect: 'cron', source: '0 9 * * 1-5' } // accepted verbatim
+expression: { dialect: 'cel', source: 'now()' }        // refused at jobs.0.schedule.expression
+expression: '   '                                      // refused at jobs.0.schedule.expression
+expression: 'not a cron'                               // accepted — syntax is croner's verdict at schedule time
+```
diff --git a/content/docs/references/ai/knowledge-source.mdx b/content/docs/references/ai/knowledge-source.mdx
@@ -65,7 +65,7 @@ const result = FileKnowledgeSourceSchema.parse(data);
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **onRecordChange** | `boolean` | optional (default: `true`) |  |
-| **cron** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron-dialect expression for a periodic full reindex. A bare string is shorthand for `{ dialect: 'cron', source }`; the parse enforces a non-empty string or an expression envelope and normalizes to the envelope — cron syntax (5- or 6-field, or an `@` alias) is the `cron` dialect engine's verdict when the expression is evaluated, not checked here. `service-knowledge` does not schedule it: the value is surfaced so an automation flow / external scheduler can trigger `reindexSource`. |
+| **cron** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron-dialect expression for a periodic full reindex. A bare string is shorthand for `{ dialect: 'cron', source }`; the parse enforces a non-empty string or an expression envelope and normalizes to the envelope — cron syntax (5- or 6-field, or an `@` alias) is the `cron` dialect engine's verdict when the expression is evaluated, not checked here. `service-knowledge` does not schedule it: the value is surfaced so an automation flow / external scheduler can trigger `reindexSource`. |
 
 
 ---
@@ -130,7 +130,7 @@ const result = FileKnowledgeSourceSchema.parse(data);
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **onRecordChange** | `boolean` | optional (default: `true`) |  |
-| **cron** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron-dialect expression for a periodic full reindex. A bare string is shorthand for `{ dialect: 'cron', source }`; the parse enforces a non-empty string or an expression envelope and normalizes to the envelope — cron syntax (5- or 6-field, or an `@` alias) is the `cron` dialect engine's verdict when the expression is evaluated, not checked here. `service-knowledge` does not schedule it: the value is surfaced so an automation flow / external scheduler can trigger `reindexSource`. |
+| **cron** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron-dialect expression for a periodic full reindex. A bare string is shorthand for `{ dialect: 'cron', source }`; the parse enforces a non-empty string or an expression envelope and normalizes to the envelope — cron syntax (5- or 6-field, or an `@` alias) is the `cron` dialect engine's verdict when the expression is evaluated, not checked here. `service-knowledge` does not schedule it: the value is surfaced so an automation flow / external scheduler can trigger `reindexSource`. |
 
 
 ---

diff --git a/content/docs/references/ai/model-registry.mdx b/content/docs/references/ai/model-registry.mdx
@@ -171,8 +171,8 @@ const result = ModelCapabilitySchema.parse(data);
 | **id** | `string` | ✅ | Unique template identifier |
 | **name** | `string` | ✅ | Template name (snake_case) |
 | **label** | `string` | ✅ | Display name |
-| **system** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | System prompt — supports `{{var}}` interpolation |
-| **user** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | User prompt template — supports `{{var}}` interpolation |
+| **system** | `string \| { dialect: 'template'; source?: string; ast?: any; meta?: object }` | optional | System prompt — supports `{{var}}` interpolation |
+| **user** | `string \| { dialect: 'template'; source?: string; ast?: any; meta?: object }` | ✅ | User prompt template — supports `{{var}}` interpolation |
 | **assistant** | `string` | optional | Assistant message prefix |
 | **variables** | `{ name: string; type?: Enum<'string' \| 'number' \| 'boolean' \| 'object' \| 'array'>; required?: boolean; defaultValue?: any; … }[]` | optional | Template variables |
 | **modelId** | `string` | optional | Recommended model ID |
@@ -260,8 +260,8 @@ const result = ModelCapabilitySchema.parse(data);
 | **id** | `string` | ✅ | Unique template identifier |
 | **name** | `string` | ✅ | Template name (snake_case) |
 | **label** | `string` | ✅ | Display name |
-| **system** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | System prompt — supports `{{var}}` interpolation |
-| **user** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | User prompt template — supports `{{var}}` interpolation |
+| **system** | `string \| { dialect: 'template'; source?: string; ast?: any; meta?: object }` | optional | System prompt — supports `{{var}}` interpolation |
+| **user** | `string \| { dialect: 'template'; source?: string; ast?: any; meta?: object }` | ✅ | User prompt template — supports `{{var}}` interpolation |
 | **assistant** | `string` | optional | Assistant message prefix |
 | **variables** | `{ name: string; type?: Enum<'string' \| 'number' \| 'boolean' \| 'object' \| 'array'>; required?: boolean; defaultValue?: any; … }[]` | optional | Template variables |
 | **modelId** | `string` | optional | Recommended model ID |

diff --git a/content/docs/references/api/export.mdx b/content/docs/references/api/export.mdx
@@ -753,7 +753,7 @@ Type: `{ sourceField: string; targetField: string; targetLabel?: string; transfo
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **cronExpression** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression for schedule |
+| **cronExpression** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression for schedule |
 | **timezone** | `string` | optional (default: `"UTC"`) | IANA timezone |
 
 ### Nested Shape: `ScheduleExportRequest.delivery`
@@ -831,7 +831,7 @@ Type: `{ sourceField: string; targetField: string; targetLabel?: string; transfo
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **cronExpression** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression for schedule |
+| **cronExpression** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression for schedule |
 | **timezone** | `string` | optional (default: `"UTC"`) | IANA timezone |
 
 ### Nested Shape: `ScheduledExport.delivery`

diff --git a/content/docs/references/api/metadata.mdx b/content/docs/references/api/metadata.mdx
@@ -787,7 +787,7 @@ Metadata query with filtering, sorting, and pagination
 | **activityMilestones** | `{ field: string; value: string; summary: string; type?: string }[]` | optional | Declarative semantic activity milestones — emit a templated timeline row when a field transitions into a value, no hook code (ADR-0052 §5b.2). |
 | **nameField** | `string` | optional | [ADR-0079] Canonical primary title field — the stored field used as the record display name (e.g. "name", "title"). |
 | **displayNameField** | `string` | optional | [DEPRECATED → nameField] Field to use as the record display name (e.g., "name", "title"). Accepted as an alias for nameField. |
-| **titleFormat** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | [DEPRECATED → nameField (ADR-0079)] Render-only title template; the server cannot return or query it, and an explicit nameField now takes precedence. Migrate a single-field title to nameField, a composite to a formula field designated as nameField. |
+| **titleFormat** | `string \| { dialect: 'template'; source?: string; ast?: any; meta?: object }` | optional | [DEPRECATED → nameField (ADR-0079)] Render-only title template; the server cannot return or query it, and an explicit nameField now takes precedence. Migrate a single-field title to nameField, a composite to a formula field designated as nameField. |
 | **highlightFields** | `string[]` | optional | [ADR-0085] Ordered most-important fields; first entry wins where only one fits. Drives default columns, cards, previews, detail highlight strip. Renamed from compactLayout. |
 | **stageField** | `string \| false` | optional | [ADR-0085] Lifecycle stage field (linear/ordered), or false to declare the status field non-linear and suppress stage heuristics. Absent = heuristic detection allowed. |
 | **editMode** | `Enum<'modal' \| 'page'>` | optional | Edit-interaction intent for records of this object: 'modal' opens the edit form as a dialog over the current view; 'page' navigates to a dedicated full-page edit route. Absent = the renderer picks its own default (objectui defaults to modal). Cross-renderer intent, not pixel styling (family). |

diff --git a/content/docs/references/automation/execution.mdx b/content/docs/references/automation/execution.mdx
@@ -341,7 +341,7 @@ const result = CheckpointSchema.parse(data);
 | :--- | :--- | :--- | :--- |
 | **id** | `string` | ✅ | Schedule instance ID |
 | **flowName** | `string` | ✅ | Flow machine name |
-| **cronExpression** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 9 * * MON-FRI` |
+| **cronExpression** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 9 * * MON-FRI` |
 | **timezone** | `string` | optional (default: `"UTC"`) | IANA timezone for cron evaluation |
 | **status** | `Enum<'active' \| 'paused' \| 'disabled' \| 'expired'>` | optional (default: `"active"`) | Current schedule status |
 | **nextRunAt** | `string` | optional | Next scheduled execution timestamp |

diff --git a/content/docs/references/data/object.mdx b/content/docs/references/data/object.mdx
@@ -162,7 +162,7 @@ const result = ApiMethod.parse(data);
 | **activityMilestones** | `{ field: string; value: string; summary: string; type?: string }[]` | optional | Declarative semantic activity milestones — emit a templated timeline row when a field transitions into a value, no hook code (ADR-0052 §5b.2). |
 | **nameField** | `string` | optional | [ADR-0079] Canonical primary title field — the stored field used as the record display name (e.g. "name", "title"). |
 | **displayNameField** | `string` | optional | [DEPRECATED → nameField] Field to use as the record display name (e.g., "name", "title"). Accepted as an alias for nameField. |
-| **titleFormat** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | [DEPRECATED → nameField (ADR-0079)] Render-only title template; the server cannot return or query it, and an explicit nameField now takes precedence. Migrate a single-field title to nameField, a composite to a formula field designated as nameField. |
+| **titleFormat** | `string \| { dialect: 'template'; source?: string; ast?: any; meta?: object }` | optional | [DEPRECATED → nameField (ADR-0079)] Render-only title template; the server cannot return or query it, and an explicit nameField now takes precedence. Migrate a single-field title to nameField, a composite to a formula field designated as nameField. |
 | **highlightFields** | `string[]` | optional | [ADR-0085] Ordered most-important fields; first entry wins where only one fits. Drives default columns, cards, previews, detail highlight strip. Renamed from compactLayout. |
 | **stageField** | `string \| false` | optional | [ADR-0085] Lifecycle stage field (linear/ordered), or false to declare the status field non-linear and suppress stage heuristics. Absent = heuristic detection allowed. |
 | **editMode** | `Enum<'modal' \| 'page'>` | optional | Edit-interaction intent for records of this object: 'modal' opens the edit form as a dialog over the current view; 'page' navigates to a dedicated full-page edit route. Absent = the renderer picks its own default (objectui defaults to modal). Cross-renderer intent, not pixel styling (family). |

diff --git a/content/docs/references/integration/connector.mdx b/content/docs/references/integration/connector.mdx
@@ -280,7 +280,7 @@ Circuit breaker configuration
 | :--- | :--- | :--- | :--- |
 | **strategy** | `Enum<'full' \| 'incremental' \| 'upsert' \| 'append_only'>` | optional (default: `"incremental"`) | Synchronization strategy |
 | **direction** | `Enum<'import' \| 'export' \| 'bidirectional'>` | optional (default: `"import"`) | Sync direction |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled sync — cron`0 */15 * * *` |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled sync — cron`0 */15 * * *` |
 | **realtimeSync** | `boolean` | optional (default: `false`) | Enable real-time sync |
 | **timestampField** | `string` | optional | Field to track last modification time |
 | **conflictResolution** | `Enum<'source_wins' \| 'target_wins' \| 'latest_wins' \| 'manual'>` | optional (default: `"latest_wins"`) | Conflict resolution strategy |
@@ -626,7 +626,7 @@ Connector type
 | :--- | :--- | :--- | :--- |
 | **strategy** | `Enum<'full' \| 'incremental' \| 'upsert' \| 'append_only'>` | optional (default: `"incremental"`) | Synchronization strategy |
 | **direction** | `Enum<'import' \| 'export' \| 'bidirectional'>` | optional (default: `"import"`) | Sync direction |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled sync — cron`0 */15 * * *` |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled sync — cron`0 */15 * * *` |
 | **realtimeSync** | `boolean` | optional (default: `false`) | Enable real-time sync |
 | **timestampField** | `string` | optional | Field to track last modification time |
 | **conflictResolution** | `Enum<'source_wins' \| 'target_wins' \| 'latest_wins' \| 'manual'>` | optional (default: `"latest_wins"`) | Conflict resolution strategy |
@@ -763,7 +763,7 @@ Connector type
 | :--- | :--- | :--- | :--- |
 | **strategy** | `Enum<'full' \| 'incremental' \| 'upsert' \| 'append_only'>` | optional (default: `"incremental"`) | Synchronization strategy |
 | **direction** | `Enum<'import' \| 'export' \| 'bidirectional'>` | optional (default: `"import"`) | Sync direction |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled sync — cron`0 */15 * * *` |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled sync — cron`0 */15 * * *` |
 | **realtimeSync** | `boolean` | optional (default: `false`) | Enable real-time sync |
 | **timestampField** | `string` | optional | Field to track last modification time |
 | **conflictResolution** | `Enum<'source_wins' \| 'target_wins' \| 'latest_wins' \| 'manual'>` | optional (default: `"latest_wins"`) | Conflict resolution strategy |