diff --git a/.changeset/typed-expression-envelope-dialect.md b/.changeset/typed-expression-envelope-dialect.md
new file mode 100644
index 0000000000..a1f6128cb6
--- /dev/null
+++ 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
index f5726eea87..0d839a946b 100644
--- 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
index 7c5d52054f..3b3d7a96d8 100644
--- 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
index cac214c442..4d4cc244b5 100644
--- 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
index babae500fc..7fd0b71cd0 100644
--- 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
index a708052d72..0afffa193b 100644
--- 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
index ea105ef57e..fd2db1e1fe 100644
--- 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
index f9f079593a..f91c078c52 100644
--- 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 |
diff --git a/content/docs/references/shared/expression.mdx b/content/docs/references/shared/expression.mdx
index c9996ae7ef..9a13e648af 100644
--- a/content/docs/references/shared/expression.mdx
+++ b/content/docs/references/shared/expression.mdx
@@ -30,6 +30,13 @@ when `CronSchedule.expression` is scheduled (`toBoundaryJobSchedule` →
 cron-typed slot is parsed and reaches no engine, and `@objectstack/formula`'s
 registered `cron` engine has no caller outside that package.
 
+A TYPED slot — one declared with `CronExpressionInputSchema` or
+`TemplateExpressionInputSchema` — takes a bare, non-blank string (shorthand
+for its own dialect) or an envelope declaring that one dialect. An envelope
+naming any other dialect, and a blank string, are refused at the slot with
+one issue whose message names the dialect and the fix. Only the untyped
+`ExpressionInputSchema` takes every declared dialect in envelope form.
+
 Those three are the whole list — it is exactly the `ExpressionDialect` enum
 below. Procedural JavaScript is **not** a dialect: it is the L2 authoring
 surface, the sandboxed, capability-gated `ScriptBody { language: 'js' }` in
@@ -77,7 +84,7 @@ Type: `string`
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **dialect** | `Enum<'cel' \| 'cron' \| 'template'>` | ✅ |  |
+| **dialect** | `'cron'` | ✅ |  |
 | **source** | `string` | optional |  |
 | **ast** | `any` | optional |  |
 | **meta** | `{ rationale?: string; generatedBy?: string }` | optional |  |
@@ -226,7 +233,7 @@ Type: `string`
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **dialect** | `Enum<'cel' \| 'cron' \| 'template'>` | ✅ |  |
+| **dialect** | `'template'` | ✅ |  |
 | **source** | `string` | optional |  |
 | **ast** | `any` | optional |  |
 | **meta** | `{ rationale?: string; generatedBy?: string }` | optional |  |
diff --git a/content/docs/references/system/cache.mdx b/content/docs/references/system/cache.mdx
index f2ae75b68b..1e370aedb1 100644
--- a/content/docs/references/system/cache.mdx
+++ b/content/docs/references/system/cache.mdx
@@ -195,7 +195,7 @@ Cache warmup strategy
 | :--- | :--- | :--- | :--- |
 | **enabled** | `boolean` | optional (default: `false`) | Enable cache warmup |
 | **strategy** | `Enum<'eager' \| 'lazy' \| 'scheduled'>` | optional (default: `"lazy"`) | Warmup strategy: eager (at startup), lazy (on first access), scheduled (cron) |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled warmup |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled warmup |
 | **patterns** | `string[]` | optional | Key patterns to warm up (e.g., "user:*", "config:*") |
 | **concurrency** | `number` | optional (default: `10`) | Maximum concurrent warmup operations |
 
@@ -258,7 +258,7 @@ Rule defining when and how cached entries are invalidated
 | :--- | :--- | :--- | :--- |
 | **enabled** | `boolean` | optional (default: `false`) | Enable cache warmup |
 | **strategy** | `Enum<'eager' \| 'lazy' \| 'scheduled'>` | optional (default: `"lazy"`) | Warmup strategy: eager (at startup), lazy (on first access), scheduled (cron) |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled warmup |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for scheduled warmup |
 | **patterns** | `string[]` | optional | Key patterns to warm up (e.g., "user:*", "config:*") |
 | **concurrency** | `number` | optional (default: `10`) | Maximum concurrent warmup operations |
 
diff --git a/content/docs/references/system/disaster-recovery.mdx b/content/docs/references/system/disaster-recovery.mdx
index b47f173d65..d7f8813ad7 100644
--- a/content/docs/references/system/disaster-recovery.mdx
+++ b/content/docs/references/system/disaster-recovery.mdx
@@ -30,7 +30,7 @@ Backup configuration
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **strategy** | `Enum<'full' \| 'incremental' \| 'differential'>` | optional (default: `"incremental"`) | Backup strategy |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for backup schedule — cron`0 2 * * *` |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for backup schedule — cron`0 2 * * *` |
 | **retention** | `{ days: number; minCopies?: number; maxCopies?: number }` | ✅ | Backup retention policy |
 | **destination** | `{ type: Enum<'s3' \| 'gcs' \| 'azure_blob' \| 'local'>; bucket?: string; path?: string; region?: string }` | ✅ | Backup storage destination |
 | **encryption** | `{ enabled?: boolean; algorithm?: Enum<'AES-256-GCM' \| 'AES-256-CBC' \| 'ChaCha20-Poly1305'>; keyId?: string }` | optional | Backup encryption settings |
@@ -137,7 +137,7 @@ Complete disaster recovery plan configuration
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **strategy** | `Enum<'full' \| 'incremental' \| 'differential'>` | optional (default: `"incremental"`) | Backup strategy |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for backup schedule — cron`0 2 * * *` |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for backup schedule — cron`0 2 * * *` |
 | **retention** | `{ days: number; minCopies?: number; maxCopies?: number }` | ✅ | Backup retention policy |
 | **destination** | `{ type: Enum<'s3' \| 'gcs' \| 'azure_blob' \| 'local'>; bucket?: string; path?: string; region?: string }` | ✅ | Backup storage destination |
 | **encryption** | `{ enabled?: boolean; algorithm?: Enum<'AES-256-GCM' \| 'AES-256-CBC' \| 'ChaCha20-Poly1305'>; keyId?: string }` | optional | Backup encryption settings |
@@ -169,7 +169,7 @@ Complete disaster recovery plan configuration
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **enabled** | `boolean` | optional (default: `false`) | Enable automated DR testing |
-| **schedule** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | optional | Cron expression for DR test schedule |
+| **schedule** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | optional | Cron expression for DR test schedule |
 | **notificationChannel** | `string` | optional | Notification channel for DR test results |
 
 ### Nested Shape: `DisasterRecoveryPlan.contacts[number]`
diff --git a/content/docs/references/system/job.mdx b/content/docs/references/system/job.mdx
index e60dea07a0..5f0c81a8cd 100644
--- a/content/docs/references/system/job.mdx
+++ b/content/docs/references/system/job.mdx
@@ -28,7 +28,7 @@ const result = CronScheduleSchema.parse(data);
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **type** | `'cron'` | ✅ |  |
-| **expression** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 0 * * *` for daily at midnight. Build emits `{dialect:"cron",source}` envelope. |
+| **expression** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 0 * * *` for daily at midnight. Build emits `{dialect:"cron",source}` envelope. |
 | **timezone** | `string` | optional (default: `"UTC"`) | Timezone for cron execution (e.g., "America/New_York") |
 
 
@@ -73,7 +73,7 @@ const result = CronScheduleSchema.parse(data);
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **type** | `'cron'` | ✅ |  |
-| **expression** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 0 * * *` for daily at midnight. Build emits `{dialect:"cron",source}` envelope. |
+| **expression** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 0 * * *` for daily at midnight. Build emits `{dialect:"cron",source}` envelope. |
 | **timezone** | `string` | optional (default: `"UTC"`) | Timezone for cron execution (e.g., "America/New_York") |
 
 ### Nested Shape: `Job.schedule[type='interval']`
@@ -176,7 +176,7 @@ This schema accepts one of the following structures:
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
 | **type** | `'cron'` | ✅ |  |
-| **expression** | `string \| { dialect: Enum<'cel' \| 'cron' \| 'template'>; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 0 * * *` for daily at midnight. Build emits `{dialect:"cron",source}` envelope. |
+| **expression** | `string \| { dialect: 'cron'; source?: string; ast?: any; meta?: object }` | ✅ | Cron expression — cron`0 0 * * *` for daily at midnight. Build emits `{dialect:"cron",source}` envelope. |
 | **timezone** | `string` | optional (default: `"UTC"`) | Timezone for cron execution (e.g., "America/New_York") |
 
 ---
diff --git a/content/docs/references/system/migration.mdx b/content/docs/references/system/migration.mdx
index a3ecaff540..180423d98c 100644
--- a/content/docs/references/system/migration.mdx
+++ b/content/docs/references/system/migration.mdx
@@ -338,7 +338,7 @@ Create a new object
 | **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). |
@@ -622,7 +622,7 @@ Create a new object
 | **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/packages/qa/dogfood/test/expression-conformance.ledger.ts b/packages/qa/dogfood/test/expression-conformance.ledger.ts
index e1cb2e8c96..0ce30ac240 100644
--- a/packages/qa/dogfood/test/expression-conformance.ledger.ts
+++ b/packages/qa/dogfood/test/expression-conformance.ledger.ts
@@ -354,7 +354,7 @@ export const EXPRESSION_SURFACE: ExprSurface[] = [
   },
   {
     // Sibling cards named in this row's note: #15500 (ratchet-key granularity)
-    // and #15028 (the envelope arm accepts any dialect).
+    // and #15028 (the envelope arm now pins the dialect — the note's last sentence).
     id: 'cron-declared-unwired',
     summary: 'cron slots on subsystems that were declared but never built — export schedules, flow schedule state, connector sync, cache warmup, DR backup/test',
     dialect: 'cron', mode: 'interpret', state: 'experimental', failPolicy: 'compile-error',
@@ -367,7 +367,7 @@ export const EXPRESSION_SURFACE: ExprSurface[] = [
       'system/cache.zod.ts:CacheWarmupSchema.schedule',
       'system/disaster-recovery.zod.ts:BackupConfigSchema.schedule', 'system/disaster-recovery.zod.ts:DisasterRecoveryPlanSchema.schedule',
     ],
-    note: 'EXPERIMENTAL — five declared cron slots with no runtime evaluator (ADR-0049 enforce-or-remove candidates; each wants its own look, and the card that surfaced them says so rather than proposing a sweep). ⚠️ TWO of these surfaces are declared TWICE: `api/export.zod.ts` `cronExpression` on `ScheduledExportSchema` and on `ScheduleExportRequestSchema`, and `system/disaster-recovery.zod.ts` `schedule` on `BackupConfigSchema` and on `DisasterRecoveryPlanSchema` (the DR `testing` block). Both pairs are genuinely the same surface twice, so one row is honest here — and now that each declaring position carries its OWN key, that judgement is written out as two `covers` entries instead of being assumed by a collapse. ⚠️ The `failPolicy` on this row is `compile-error` because the PARSE is the only thing that ever refuses one of these values; it is not a claim that cron SYNTAX is checked. It is not: `@objectstack/formula` cronEngine validates 5/6-field patterns and `@` aliases, and has ZERO consumers outside packages/formula — nothing routes these slots through it. And per the sibling finding on the dialect union, the envelope arm of `CronExpressionInputSchema` accepts any declared dialect, so even the parse does not pin these to `cron`.',
+    note: 'EXPERIMENTAL — five declared cron slots with no runtime evaluator (ADR-0049 enforce-or-remove candidates; each wants its own look, and the card that surfaced them says so rather than proposing a sweep). ⚠️ TWO of these surfaces are declared TWICE: `api/export.zod.ts` `cronExpression` on `ScheduledExportSchema` and on `ScheduleExportRequestSchema`, and `system/disaster-recovery.zod.ts` `schedule` on `BackupConfigSchema` and on `DisasterRecoveryPlanSchema` (the DR `testing` block). Both pairs are genuinely the same surface twice, so one row is honest here — and now that each declaring position carries its OWN key, that judgement is written out as two `covers` entries instead of being assumed by a collapse. ⚠️ The `failPolicy` on this row is `compile-error` because the PARSE is the only thing that ever refuses one of these values; it is not a claim that cron SYNTAX is checked. It is not: `@objectstack/formula` cronEngine validates 5/6-field patterns and `@` aliases, and has ZERO consumers outside packages/formula — nothing routes these slots through it. The parse now DOES pin these slots to the cron dialect (the sibling finding on the dialect union is closed): the envelope arm of `CronExpressionInputSchema` accepts a `cron` envelope only and its bare-string arm refuses a blank string, each with one issue at the slot naming the fix — and it still judges no cron syntax, by position: no grammar is restated in spec; `croner` judges the pattern where a schedule is wired (`cron-job-schedule`).',
   },
 
   // ── TEMPLATE dialect (#15027) ─────────────────────────────────────────────
diff --git a/packages/spec/api-surface/shared.json b/packages/spec/api-surface/shared.json
index 8cb6bb7860..1305100de1 100644
--- a/packages/spec/api-surface/shared.json
+++ b/packages/spec/api-surface/shared.json
@@ -81,8 +81,11 @@
     "StrictUnknownKeyErrorOptions (interface)",
     "SystemIdentifier (type)",
     "SystemIdentifierSchema (const)",
+    "TYPED_EXPRESSION_DIALECT_ONLY (const)",
+    "TYPED_EXPRESSION_SOURCE_REQUIRED (const)",
     "TemplateExpressionInput (type)",
     "TemplateExpressionInputSchema (const)",
+    "TypedExpressionDialect (type)",
     "VISIBILITY_ALIAS_KEYS (const)",
     "VISIBILITY_STRICT_OPTIONS (const)",
     "ValueDomain (type)",
diff --git a/packages/spec/export-origins/shared.json b/packages/spec/export-origins/shared.json
index 4a0b18a446..3e3567fe31 100644
--- a/packages/spec/export-origins/shared.json
+++ b/packages/spec/export-origins/shared.json
@@ -81,8 +81,11 @@
     "StrictUnknownKeyErrorOptions": "src/shared/suggestions.zod.ts#StrictUnknownKeyErrorOptions (interface)",
     "SystemIdentifier": "src/shared/identifiers.zod.ts#SystemIdentifier (type)",
     "SystemIdentifierSchema": "src/shared/identifiers.zod.ts#SystemIdentifierSchema (const)",
+    "TYPED_EXPRESSION_DIALECT_ONLY": "src/shared/expression.zod.ts#TYPED_EXPRESSION_DIALECT_ONLY (const)",
+    "TYPED_EXPRESSION_SOURCE_REQUIRED": "src/shared/expression.zod.ts#TYPED_EXPRESSION_SOURCE_REQUIRED (const)",
     "TemplateExpressionInput": "src/shared/expression.zod.ts#TemplateExpressionInput (type)",
     "TemplateExpressionInputSchema": "src/shared/expression.zod.ts#TemplateExpressionInputSchema (const)",
+    "TypedExpressionDialect": "src/shared/expression.zod.ts#TypedExpressionDialect (type)",
     "VISIBILITY_ALIAS_KEYS": "src/shared/visibility.ts#VISIBILITY_ALIAS_KEYS (const)",
     "VISIBILITY_STRICT_OPTIONS": "src/shared/visibility.ts#VISIBILITY_STRICT_OPTIONS (const)",
     "ValueDomain": "src/shared/value-domain.zod.ts#ValueDomain (type)",
diff --git a/packages/spec/src/ai/knowledge-source.test.ts b/packages/spec/src/ai/knowledge-source.test.ts
index 539b33b967..df0f805c65 100644
--- a/packages/spec/src/ai/knowledge-source.test.ts
+++ b/packages/spec/src/ai/knowledge-source.test.ts
@@ -10,10 +10,13 @@
 // schema ENFORCES was measured before these pins were written, and the pins
 // state exactly that — no more:
 //
-// - a bare non-empty string normalizes to `{ dialect: 'cron', source }`;
-// - an expression envelope passes through;
-// - an empty string, a non-string, or an envelope naming an unknown dialect
-//   is refused with `invalid_union` at the slot's own path;
+// - a bare non-blank string normalizes to `{ dialect: 'cron', source }`;
+// - a `{ dialect: 'cron' }` envelope passes through;
+// - a blank string (empty or whitespace-only), a non-string, or an envelope
+//   naming any dialect but `cron` is refused with ONE `invalid_union` at the
+//   slot's own path whose message names the fix — the shared dialect fixed its
+//   envelope arm and learned to trim at #15028 / #15035; the sentences are
+//   `TYPED_EXPRESSION_SOURCE_REQUIRED.cron` / `TYPED_EXPRESSION_DIALECT_ONLY.cron`;
 // - cron SYNTAX is not judged at parse time. `'not a cron'` normalizes like
 //   any other string: the syntax verdict belongs to the `cron` dialect engine
 //   (`@objectstack/formula` cron-engine — 5- or 6-field, or an `@` alias) when
@@ -23,6 +26,7 @@
 //   rewritten in the same commit.
 
 import { describe, expect, it } from 'vitest';
+import { TYPED_EXPRESSION_DIALECT_ONLY, TYPED_EXPRESSION_SOURCE_REQUIRED } from '../shared/expression.zod';
 import {
   KnowledgeRefreshPolicySchema,
   KnowledgeSourceSchema,
@@ -67,15 +71,17 @@ describe('KnowledgeRefreshPolicySchema.cron — the typed cron slot (#14825)', (
     if (withoutRefresh.success) expect(withoutRefresh.data.refresh?.cron).toBeUndefined();
   });
 
-  it('refuses an empty string with `invalid_union` at `refresh.cron`', () => {
-    const r = KnowledgeSourceSchema.safeParse({ ...SOURCE, refresh: { cron: '' } });
-    expect(r.success).toBe(false);
-    if (r.success) return;
-    const issue = r.error.issues.find((i) => i.path.join('.') === 'refresh.cron');
-    expect(issue, JSON.stringify(r.error.issues)).toBeDefined();
-    expect(issue?.code).toBe('invalid_union');
-    expect(issue?.message.split('.')[0]).toBe('Invalid input');
-  });
+  it.each([['the empty string', ''], ['whitespace only', '  \t']])(
+    'refuses a blank string (%s) with ONE `invalid_union` at `refresh.cron` whose message is the cron source-required sentence',
+    (_label, blank) => {
+      const r = KnowledgeSourceSchema.safeParse({ ...SOURCE, refresh: { cron: blank } });
+      expect(r.success).toBe(false);
+      if (r.success) return;
+      expect(r.error.issues.map((i) => [i.code, i.path.join('.'), i.message])).toEqual([
+        ['invalid_union', 'refresh.cron', TYPED_EXPRESSION_SOURCE_REQUIRED.cron],
+      ]);
+    },
+  );
 
   it('refuses a non-string value with `invalid_union` at `cron`', () => {
     const r = KnowledgeRefreshPolicySchema.safeParse({ cron: 42 });
@@ -84,12 +90,16 @@ describe('KnowledgeRefreshPolicySchema.cron — the typed cron slot (#14825)', (
     expect(r.error.issues.map((i) => [i.code, i.path.join('.')])).toEqual([['invalid_union', 'cron']]);
   });
 
-  it('refuses an envelope naming a dialect the protocol does not declare', () => {
-    // `js` was retired from `ExpressionDialect` (#3278, ADR-0058 addendum).
-    const r = KnowledgeRefreshPolicySchema.safeParse({ cron: { dialect: 'js', source: 'x' } });
+  it.each([
+    ['a dialect the protocol does not declare (`js`, retired at #3278, ADR-0058 addendum)', 'js'],
+    ['a declared dialect that is not this slot\'s (`cel`, #15028)', 'cel'],
+  ])('refuses an envelope naming %s with ONE `invalid_union` at `cron` whose message is the cron dialect-only sentence', (_label, dialect) => {
+    const r = KnowledgeRefreshPolicySchema.safeParse({ cron: { dialect, source: 'x' } });
     expect(r.success).toBe(false);
     if (r.success) return;
-    expect(r.error.issues.map((i) => [i.code, i.path.join('.')])).toEqual([['invalid_union', 'cron']]);
+    expect(r.error.issues.map((i) => [i.code, i.path.join('.'), i.message])).toEqual([
+      ['invalid_union', 'cron', TYPED_EXPRESSION_DIALECT_ONLY.cron],
+    ]);
   });
 
   it('does NOT judge cron syntax at parse time — measured, and the describe promises no more (declared = enforced)', () => {
diff --git a/packages/spec/src/shared/expression.zod.ts b/packages/spec/src/shared/expression.zod.ts
index 0176f52181..bbccf2c39b 100644
--- a/packages/spec/src/shared/expression.zod.ts
+++ b/packages/spec/src/shared/expression.zod.ts
@@ -28,6 +28,13 @@ import { z } from 'zod';
  * cron-typed slot is parsed and reaches no engine, and `@objectstack/formula`'s
  * registered `cron` engine has no caller outside that package.
  *
+ * A TYPED slot — one declared with `CronExpressionInputSchema` or
+ * `TemplateExpressionInputSchema` — takes a bare, non-blank string (shorthand
+ * for its own dialect) or an envelope declaring that one dialect. An envelope
+ * naming any other dialect, and a blank string, are refused at the slot with
+ * one issue whose message names the dialect and the fix. Only the untyped
+ * `ExpressionInputSchema` takes every declared dialect in envelope form.
+ *
  * Those three are the whole list — it is exactly the `ExpressionDialect` enum
  * below. Procedural JavaScript is **not** a dialect: it is the L2 authoring
  * surface, the sandboxed, capability-gated `ScriptBody { language: 'js' }` in
@@ -168,25 +175,120 @@ export const ExpressionInputSchema = z.union([
 export type ExpressionInput = z.input<typeof ExpressionInputSchema>;
 
 /**
- * Cron-typed input shape: a bare string is shorthand for `{ dialect: 'cron',
- * source }` (not `cel`). Use this for `schedule` / `cronExpression` fields so
- * authors can write `'0 9 * * 1-5'` without manually wrapping.
+ * The dialects that have a TYPED input schema below. On a typed slot the bare
+ * string is shorthand for this dialect, and the envelope arm accepts this
+ * dialect only.
+ */
+export type TypedExpressionDialect = Extract<ExpressionDialect, 'cron' | 'template'>;
+
+/**
+ * The one sentence a TYPED slot refuses a blank string with — empty or
+ * whitespace-only, the notion of blank `EvaluatedExpressionSchema` applies
+ * (`source.trim()`), so the two typed schemas and the evaluated one share one
+ * rule. Its own words rather than {@link EVALUATED_EXPRESSION_SOURCE_REQUIRED},
+ * because that sentence prescribes `{ dialect: 'cel', source }` — the one
+ * envelope a typed slot refuses.
+ */
+export const TYPED_EXPRESSION_SOURCE_REQUIRED: Readonly<Record<TypedExpressionDialect, string>> = {
+  cron:
+    'A cron-typed slot needs a non-blank cron expression: a bare string is shorthand for '
+    + '`{ dialect: \'cron\', source }`, and a blank one would normalize to an envelope with nothing to schedule. '
+    + 'Write `\'0 9 * * 1-5\'` or `{ dialect: \'cron\', source: \'0 9 * * 1-5\' }`; no cron syntax is judged '
+    + 'here — `croner` refuses an invalid pattern where a schedule is wired.',
+  template:
+    'A template-typed slot needs a non-blank template: a bare string is shorthand for '
+    + '`{ dialect: \'template\', source }`, and a blank one would normalize to an envelope with nothing to '
+    + 'interpolate. Write `\'{{record.name}}\'` or `{ dialect: \'template\', source: \'{{record.name}}\' }`.',
+};
+
+/**
+ * The one sentence a TYPED slot refuses a foreign-dialect envelope with (and
+ * any value that is neither a string nor an envelope). It names the slot's
+ * dialect first, then the fix, so the prescription travels with the refusal.
+ */
+export const TYPED_EXPRESSION_DIALECT_ONLY: Readonly<Record<TypedExpressionDialect, string>> = {
+  cron:
+    'A cron-typed slot accepts a bare cron string or an envelope declaring `dialect: \'cron\'` only: an '
+    + 'envelope naming another dialect would validate and then have nothing to schedule. '
+    + 'Write `\'0 9 * * 1-5\'` or `{ dialect: \'cron\', source: \'0 9 * * 1-5\' }`.',
+  template:
+    'A template-typed slot accepts a bare template string or an envelope declaring `dialect: \'template\'` '
+    + 'only: an envelope naming another dialect would validate and then have nothing to interpolate. '
+    + 'Write `\'{{record.name}}\'` or `{ dialect: \'template\', source: \'{{record.name}}\' }`.',
+};
+
+/**
+ * The two arms a typed input union shares, spelled once. Each typed schema
+ * below composes them around its own `z.literal(dialect)` envelope arm.
+ *
+ * The refusal shape is measured, not assumed (zod 4.4): a union reports the
+ * one arm that did not abort, else `invalid_union`. Both arms here abort on a
+ * foreign value — the string arm is a pipe, whose transform aborts the arm on
+ * any issue, and the envelope arm's `z.literal` aborts on a foreign dialect —
+ * so every refusal is ONE `invalid_union` at the slot, and the union's own
+ * error map is where the message lives: the source-required sentence for a
+ * string input, the dialect-only sentence for everything else. A `.refine` on
+ * the envelope arm would surface as `custom` at `dialect` instead, but would
+ * leave the input TYPE, the JSON Schema and the generated reference page
+ * declaring every dialect on a typed slot; the literal keeps all four surfaces
+ * saying one thing. The one refusal `ExpressionSchema` carries — neither
+ * `source` nor `ast` — still surfaces on its own, with its own message: that
+ * arm does not abort on it.
+ *
+ * The string arm's transform returns the narrowed `{ dialect, source }`, not
+ * the wide `Expression`: the parsed value of a typed slot must stay assignable
+ * to its own input type (`ObjectStackDefinitionSchema.parse` output is handed
+ * to validators typed with the input shape), and it is — a same-dialect
+ * envelope is both.
+ */
+function typedExpressionStringArm<D extends TypedExpressionDialect>(dialect: D) {
+  return z.string()
+    .refine((source) => source.trim().length > 0, { message: TYPED_EXPRESSION_SOURCE_REQUIRED[dialect] })
+    .transform((source) => ({ dialect, source }));
+}
+
+function typedExpressionUnionParams(dialect: TypedExpressionDialect): { error: (issue: { input?: unknown }) => string } {
+  return {
+    error: (issue) => (typeof issue.input === 'string'
+      ? TYPED_EXPRESSION_SOURCE_REQUIRED[dialect]
+      : TYPED_EXPRESSION_DIALECT_ONLY[dialect]),
+  };
+}
+
+/**
+ * Cron-typed input shape: a bare, non-blank string is shorthand for
+ * `{ dialect: 'cron', source }`, and an envelope must declare `dialect: 'cron'`
+ * — a `cel` or `template` envelope is refused at the slot, naming the fix
+ * (`TYPED_EXPRESSION_DIALECT_ONLY.cron`), as is a blank string
+ * (`TYPED_EXPRESSION_SOURCE_REQUIRED.cron`). Use this for `schedule` /
+ * `cronExpression` fields so authors can write `'0 9 * * 1-5'` without
+ * manually wrapping.
+ *
+ * No cron syntax is judged at parse time — `'not a cron'` normalizes like any
+ * other string. `croner` judges the pattern where a schedule is wired
+ * (`CronSchedule.expression` → `toBoundaryJobSchedule` → `CronJobAdapter`);
+ * every other cron-typed slot reaches no engine, and no grammar is restated
+ * here.
  */
 export const CronExpressionInputSchema = z.union([
-  z.string().min(1).transform((source): Expression => ({ dialect: 'cron', source })),
-  ExpressionSchema,
-]);
+  typedExpressionStringArm('cron'),
+  ExpressionSchema.safeExtend({ dialect: z.literal('cron') }),
+], typedExpressionUnionParams('cron'));
 export type CronExpressionInput = z.input<typeof CronExpressionInputSchema>;
 
 /**
- * Template-typed input shape: a bare string is shorthand for
- * `{ dialect: 'template', source }`. Use this for notification subjects/bodies,
- * titleFormat, prompt templates — anything with `{{var}}` interpolation.
+ * Template-typed input shape: a bare, non-blank string is shorthand for
+ * `{ dialect: 'template', source }`, and an envelope must declare
+ * `dialect: 'template'` — a `cel` or `cron` envelope is refused at the slot,
+ * naming the fix (`TYPED_EXPRESSION_DIALECT_ONLY.template`), as is a blank
+ * string (`TYPED_EXPRESSION_SOURCE_REQUIRED.template`). Use this for
+ * notification subjects/bodies, titleFormat, prompt templates — anything with
+ * `{{var}}` interpolation. No template syntax is judged at parse time.
  */
 export const TemplateExpressionInputSchema = z.union([
-  z.string().min(1).transform((source): Expression => ({ dialect: 'template', source })),
-  ExpressionSchema,
-]);
+  typedExpressionStringArm('template'),
+  ExpressionSchema.safeExtend({ dialect: z.literal('template') }),
+], typedExpressionUnionParams('template'));
 export type TemplateExpressionInput = z.input<typeof TemplateExpressionInputSchema>;
 
 /**
diff --git a/packages/spec/src/shared/typed-expression-envelope-dialect.test.ts b/packages/spec/src/shared/typed-expression-envelope-dialect.test.ts
new file mode 100644
index 0000000000..69546c235a
--- /dev/null
+++ b/packages/spec/src/shared/typed-expression-envelope-dialect.test.ts
@@ -0,0 +1,212 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * `CronExpressionInputSchema` / `TemplateExpressionInputSchema` — a TYPED slot
+ * fixes its dialect on BOTH arms (#15028), and refuses a blank string the way
+ * `EvaluatedExpressionSchema` does (#15035, the census's correction).
+ *
+ * Before: the envelope arm was the unrestricted `ExpressionSchema`, so a cron
+ * slot parsed `{ dialect: 'cel', source }` green and whatever read it received
+ * an envelope it could not run; and the string arm's `.min(1)` did not trim,
+ * so `'   '` normalized to `{ dialect: 'cron', source: '   ' }` on all twelve
+ * typed positions. Both were copy-paste artifacts of the untyped schema, never
+ * a decision; the narrowing refuses zero measured author values (32 cron, 14
+ * template — the #15035 census).
+ *
+ * Every refusal pin asserts the issue's `code`, `path` and message — never
+ * `success === false` alone — and that it is the ONLY top-level issue. The
+ * deliberate NON-verdict is pinned alongside: cron / template SYNTAX is still
+ * not judged at parse time (`'not a cron'` normalizes), because no grammar is
+ * restated in spec — `croner` judges the one wired slot where it is scheduled.
+ * The control is the persistence contract itself: `ExpressionSchema` still
+ * accepts every declared dialect, because it was not narrowed.
+ */
+
+import { describe, expect, it } from 'vitest';
+import { z } from 'zod';
+
+import { ObjectStackDefinitionSchema } from '../stack.zod.js';
+import {
+  CronExpressionInputSchema,
+  ExpressionSchema,
+  TemplateExpressionInputSchema,
+  TYPED_EXPRESSION_DIALECT_ONLY,
+  TYPED_EXPRESSION_SOURCE_REQUIRED,
+  type CronExpressionInput,
+  type TemplateExpressionInput,
+  type TypedExpressionDialect,
+} from './expression.zod.js';
+
+const NEITHER_SOURCE_NOR_AST = 'Expression requires at least one of `source` or `ast`';
+
+/** Parse `value` in a slot named `slot`, so the path is the slot's own. */
+function slotIssues(schema: z.ZodType, value: unknown) {
+  const result = z.object({ slot: schema.optional() }).safeParse({ slot: value });
+  return result.success
+    ? []
+    : result.error.issues.map((i) => ({ code: i.code, path: i.path.map(String).join('.'), message: i.message }));
+}
+
+function slotValue(schema: z.ZodType, value: unknown): unknown {
+  const result = z.object({ slot: schema.optional() }).safeParse({ slot: value });
+  expect(result.success, result.success ? '' : JSON.stringify(result.error.issues)).toBe(true);
+  return result.success ? (result.data as { slot: unknown }).slot : undefined;
+}
+
+const TYPED: ReadonlyArray<{
+  dialect: TypedExpressionDialect;
+  schema: z.ZodType;
+  good: string;
+  unjudged: string;
+  foreign: readonly ['cel', 'template'] | readonly ['cel', 'cron'];
+}> = [
+  { dialect: 'cron', schema: CronExpressionInputSchema, good: '0 9 * * 1-5', unjudged: 'not a cron', foreign: ['cel', 'template'] },
+  { dialect: 'template', schema: TemplateExpressionInputSchema, good: '{{record.name}}', unjudged: 'not a template {{{', foreign: ['cel', 'cron'] },
+];
+
+describe.each(TYPED)('$dialect-typed slot — the dialect is fixed on both arms, and blank is refused (#15028 / #15035)', ({ dialect, schema, good, unjudged, foreign }) => {
+  const dialectOnly = TYPED_EXPRESSION_DIALECT_ONLY[dialect];
+  const sourceRequired = TYPED_EXPRESSION_SOURCE_REQUIRED[dialect];
+
+  it('ACCEPTS a bare string and normalizes it to its own dialect', () => {
+    expect(slotValue(schema, good)).toEqual({ dialect, source: good });
+    // Surrounding whitespace is authored, not blank — the notion of blank is `.trim()`, and the source is kept as written.
+    expect(slotValue(schema, `  ${good}  `)).toEqual({ dialect, source: `  ${good}  ` });
+  });
+
+  it('ACCEPTS a same-dialect envelope verbatim, authorship metadata included', () => {
+    const envelope = { dialect, source: good, meta: { rationale: 'r', generatedBy: 'test' } };
+    expect(slotValue(schema, envelope)).toEqual(envelope);
+  });
+
+  it('still ACCEPTS an `ast`-only envelope of its own dialect — a typed slot persists, it is not an evaluated slot', () => {
+    const envelope = { dialect, ast: { kind: 'const' } };
+    expect(slotValue(schema, envelope)).toEqual(envelope);
+  });
+
+  it.each(foreign)('REFUSES a `%s` envelope: one `invalid_union` at the slot, the dialect-only sentence', (other) => {
+    expect(slotIssues(schema, { dialect: other, source: good })).toEqual([
+      { code: 'invalid_union', path: 'slot', message: dialectOnly },
+    ]);
+  });
+
+  it('REFUSES an envelope naming a dialect the protocol does not declare (`js`), with the same named issue', () => {
+    expect(slotIssues(schema, { dialect: 'js', source: 'x' })).toEqual([
+      { code: 'invalid_union', path: 'slot', message: dialectOnly },
+    ]);
+  });
+
+  it('REFUSES a value that is neither a string nor an envelope, with the dialect-only sentence', () => {
+    expect(slotIssues(schema, 42)).toEqual([{ code: 'invalid_union', path: 'slot', message: dialectOnly }]);
+    expect(slotIssues(schema, { source: good })).toEqual([{ code: 'invalid_union', path: 'slot', message: dialectOnly }]);
+  });
+
+  it.each([
+    ['the empty string', ''],
+    ['three spaces', '   '],
+    ['a tab and a newline', '\t\n'],
+  ])('REFUSES a blank string (%s): one `invalid_union` at the slot, the source-required sentence', (_label, blank) => {
+    expect(slotIssues(schema, blank)).toEqual([{ code: 'invalid_union', path: 'slot', message: sourceRequired }]);
+  });
+
+  it('KEEPS the refusal `ExpressionSchema` carries — an envelope with neither `source` nor `ast` — under its own message', () => {
+    expect(slotIssues(schema, { dialect })).toEqual([{ code: 'custom', path: 'slot', message: NEITHER_SOURCE_NOR_AST }]);
+  });
+
+  it('does NOT judge syntax at parse time — the deliberate non-verdict: no grammar is restated in spec', () => {
+    expect(slotValue(schema, unjudged)).toEqual({ dialect, source: unjudged });
+  });
+
+  it('the two sentences name the dialect in their first sentence and quote the fix', () => {
+    for (const sentence of [dialectOnly, sourceRequired]) {
+      expect(sentence.startsWith(`A ${dialect}-typed slot`)).toBe(true);
+      expect(sentence).toContain(`dialect: '${dialect}'`);
+      expect(sentence).toContain(`{ dialect: '${dialect}', source: '${good}' }`);
+    }
+    expect(dialectOnly).not.toBe(sourceRequired);
+  });
+});
+
+describe('controls and the author-facing type', () => {
+  it('control: `ExpressionSchema` itself was NOT narrowed — every declared dialect still parses as an envelope', () => {
+    for (const dialect of ['cel', 'cron', 'template']) {
+      expect(ExpressionSchema.safeParse({ dialect, source: 'x' }).success).toBe(true);
+    }
+  });
+
+  it('the cron sentences say no cron syntax is judged here and name who judges it', () => {
+    expect(TYPED_EXPRESSION_SOURCE_REQUIRED.cron).toContain('no cron syntax is judged here');
+    expect(TYPED_EXPRESSION_SOURCE_REQUIRED.cron).toContain('`croner`');
+  });
+
+  it('narrows the author TYPE too: a foreign-dialect envelope is a compile error before it is a parse error', () => {
+    const cronOk: CronExpressionInput = { dialect: 'cron', source: '0 9 * * *' };
+    // @ts-expect-error — `cel` is not a cron-typed slot's dialect.
+    const cronBad: CronExpressionInput = { dialect: 'cel', source: 'now()' };
+    const templateOk: TemplateExpressionInput = { dialect: 'template', source: '{{x}}' };
+    // @ts-expect-error — `cron` is not a template-typed slot's dialect.
+    const templateBad: TemplateExpressionInput = { dialect: 'cron', source: '0 9 * * *' };
+    const bare: CronExpressionInput = '0 9 * * *';
+    expect([cronOk, cronBad, templateOk, templateBad, bare]).toHaveLength(5);
+  });
+});
+
+/**
+ * Through the stack: the three typed positions a `defineStack` manifest can
+ * reach (`jobs[].schedule.expression`, `connectors[].syncConfig.schedule`,
+ * `objects[].titleFormat`) refuse at the named path via
+ * `ObjectStackDefinitionSchema` — the choke point `os validate` parses through.
+ */
+describe('through `ObjectStackDefinitionSchema` — the stack-reachable typed slots refuse at the named path', () => {
+  const manifest = { id: 'com.example.typed', name: 'typed-slots', version: '1.0.0', type: 'app' as const };
+  const job = (expression: unknown) => ({ name: 'nightly', schedule: { type: 'cron' as const, expression }, handler: 'nightly' });
+  const connector = (schedule: unknown) => ({ name: 'sap', label: 'SAP', type: 'saas' as const, syncConfig: { schedule } });
+  const object = (titleFormat: unknown) => ({ name: 'thing', fields: { name: { type: 'text' as const } }, titleFormat });
+
+  function stackIssues(stack: unknown) {
+    const result = ObjectStackDefinitionSchema.safeParse(stack);
+    return result.success
+      ? []
+      : result.error.issues.map((i) => ({ code: i.code, path: i.path.map(String).join('.'), message: i.message }));
+  }
+
+  it('control: the same stack with a bare string in every typed slot parses green and normalizes each to its envelope', () => {
+    const result = ObjectStackDefinitionSchema.safeParse({
+      manifest, jobs: [job('0 1 * * *')], connectors: [connector('*/15 * * * *')], objects: [object('{{record.name}}')],
+    });
+    expect(result.success, result.success ? '' : JSON.stringify(result.error.issues)).toBe(true);
+    if (!result.success) return;
+    expect(result.data.jobs?.[0]?.schedule).toMatchObject({ expression: { dialect: 'cron', source: '0 1 * * *' } });
+    expect(result.data.connectors?.[0]?.syncConfig?.schedule).toEqual({ dialect: 'cron', source: '*/15 * * * *' });
+    expect(result.data.objects?.[0]?.titleFormat).toEqual({ dialect: 'template', source: '{{record.name}}' });
+  });
+
+  it('`jobs[].schedule.expression` refuses a `cel` envelope at `jobs.0.schedule.expression`', () => {
+    expect(stackIssues({ manifest, jobs: [job({ dialect: 'cel', source: 'now()' })] })).toEqual([
+      { code: 'invalid_union', path: 'jobs.0.schedule.expression', message: TYPED_EXPRESSION_DIALECT_ONLY.cron },
+    ]);
+  });
+
+  it('`jobs[].schedule.expression` refuses a blank string at `jobs.0.schedule.expression`', () => {
+    expect(stackIssues({ manifest, jobs: [job('   ')] })).toEqual([
+      { code: 'invalid_union', path: 'jobs.0.schedule.expression', message: TYPED_EXPRESSION_SOURCE_REQUIRED.cron },
+    ]);
+  });
+
+  it('`connectors[].syncConfig.schedule` refuses a `template` envelope at `connectors.0.syncConfig.schedule`', () => {
+    expect(stackIssues({ manifest, connectors: [connector({ dialect: 'template', source: '{{x}}' })] })).toEqual([
+      { code: 'invalid_union', path: 'connectors.0.syncConfig.schedule', message: TYPED_EXPRESSION_DIALECT_ONLY.cron },
+    ]);
+  });
+
+  it('`objects[].titleFormat` refuses a `cron` envelope at `objects.0.titleFormat`', () => {
+    expect(stackIssues({ manifest, objects: [object({ dialect: 'cron', source: '0 9 * * *' })] })).toEqual([
+      { code: 'invalid_union', path: 'objects.0.titleFormat', message: TYPED_EXPRESSION_DIALECT_ONLY.template },
+    ]);
+  });
+
+  it('the deliberate non-verdict holds through the stack: `\'not a cron\'` in a job schedule parses green', () => {
+    const result = ObjectStackDefinitionSchema.safeParse({ manifest, jobs: [job('not a cron')] });
+    expect(result.success, result.success ? '' : JSON.stringify(result.error.issues)).toBe(true);
+  });
+});