diff --git a/.changeset/flow-edge-condition-evaluated-slot.md b/.changeset/flow-edge-condition-evaluated-slot.md
index 37edaaed6f..9b93572b23 100644
--- a/.changeset/flow-edge-condition-evaluated-slot.md
+++ b/.changeset/flow-edge-condition-evaluated-slot.md
@@ -61,7 +61,10 @@ edges:
   refused by `evaluateCondition` with the same sentence, instead of answering a
   silent `false`. An `ast` BESIDE a string `source` is still admitted
   everywhere. The whitespace-only STRING ruling on `config.condition` (#15662:
-  consistent `false` on both sides) is untouched.
+  consistent `false` on both sides) is untouched by this change, but it does not
+  survive the release that carries it: two sibling notes in that release refuse
+  the value, at `registerFlow` (#17322, `@objectstack/service-automation`) and
+  at `objectstack validate` (#17495, `@objectstack/lint`).
 - **Three doors agree, through the spec.** `registerFlow` refuses the flow at
   `FlowSchema.parse` (edge) or at its structural pass (`config.condition`);
   `objectstack validate` refuses it at its `ObjectStackDefinitionSchema` parse
@@ -80,7 +83,7 @@ the refusal itself carries the prescription.
 
 **A flow ALREADY STORED in `sys_metadata` stops running entirely — the whole
 flow, not just the edge.** The paragraph above is the author's remedy, at
-`objectstack validate` / `POST /flows`; a stored row has no author in front of
+`objectstack validate` / `POST /api/v1/automation`; a stored row has no author in front of
 it. Stored flows are deliberately NOT canonicalized by
 `applyConversionsToStoredItem` (`spec/src/conversions/stored.ts`, and the same
 skip in `metadata/src/loaders/database-loader.ts`'s `rowToData`) — flow-node
@@ -104,5 +107,9 @@ door, `objectstack validate`, which locates the same edge at
 judgment for a consumer replaying the chain.
 
 Not touched here: `start.config.condition` has no Zod schema to narrow (the
-start node's `config` is an open record); its producer-side gate is the
-structural refusal above, which this change tightens but does not type.
+start node's `config` is an open record). Its producer-side gate is the
+structural pass at `registerFlow` and `objectstack validate`: the shape refusal
+above, which this change tightens but does not type, and after it a blank-source
+check that runs this change's `EvaluatedExpressionInputSchema` on the
+condition's `source` (added by #17322 at `registerFlow` and by #17495 at
+`objectstack validate`).
diff --git a/packages/spec/src/migrations/entries/semantic/18.flow-edge-condition-evaluated-slot-source-required.ts b/packages/spec/src/migrations/entries/semantic/18.flow-edge-condition-evaluated-slot-source-required.ts
index b6a058ad53..b8c1cf8c88 100644
--- a/packages/spec/src/migrations/entries/semantic/18.flow-edge-condition-evaluated-slot-source-required.ts
+++ b/packages/spec/src/migrations/entries/semantic/18.flow-edge-condition-evaluated-slot-source-required.ts
@@ -18,7 +18,7 @@ export const entry: SemanticMigration = {
     + 'than deriving a second one; it is the same decision reaching the second slot, which is why '
     + 'it is named here instead of in an entry of its own. Reachable wherever a flow is authored '
     + 'or stored: defineStack({ flows }) sources, an exported stack passed to objectstack validate, '
-    + 'a POST /flows body, and a flow row already sitting in sys_metadata',
+    + 'a POST /api/v1/automation body, and a flow row already sitting in sys_metadata',
   replacement:
     'a non-blank `source` — `{ dialect: \'cel\', source: \'record.amount > 10\' }`, or the bare '
     + 'string `\'record.amount > 10\'` — if the edge was meant to branch; or REMOVE the '
@@ -60,7 +60,7 @@ export const entry: SemanticMigration = {
   acceptanceCriteria:
     'Grep every authored structural condition — BOTH `edges[].condition` and a node\'s '
     + '`config.condition` (a `decision` node\'s predicate, and on a `start` node the trigger '
-    + 'gate) — in `defineStack({ flows })` sources, exported stacks and `POST /flows` bodies, and '
+    + 'gate) — in `defineStack({ flows })` sources, exported stacks and `POST /api/v1/automation` bodies, and '
     + 'every flow row in `sys_metadata`, for an envelope with no `source` key and for a `source` '
     + '(or bare string) that is empty after trimming. ⚠️ Sweeping only the edge key leaves the '
     + 'node key unswept, and the node key is the one with no schema in front of it. For each '
diff --git a/packages/spec/src/migrations/registry.ts b/packages/spec/src/migrations/registry.ts
index 30cf33582d..f14b1dffd0 100644
--- a/packages/spec/src/migrations/registry.ts
+++ b/packages/spec/src/migrations/registry.ts
@@ -9065,7 +9065,7 @@ const step18: MigrationStep = {
         + 'than deriving a second one; it is the same decision reaching the second slot, which is why '
         + 'it is named here instead of in an entry of its own. Reachable wherever a flow is authored '
         + 'or stored: defineStack({ flows }) sources, an exported stack passed to objectstack validate, '
-        + 'a POST /flows body, and a flow row already sitting in sys_metadata',
+        + 'a POST /api/v1/automation body, and a flow row already sitting in sys_metadata',
       replacement:
         'a non-blank `source` — `{ dialect: \'cel\', source: \'record.amount > 10\' }`, or the bare '
         + 'string `\'record.amount > 10\'` — if the edge was meant to branch; or REMOVE the '
@@ -9107,7 +9107,7 @@ const step18: MigrationStep = {
       acceptanceCriteria:
         'Grep every authored structural condition — BOTH `edges[].condition` and a node\'s '
         + '`config.condition` (a `decision` node\'s predicate, and on a `start` node the trigger '
-        + 'gate) — in `defineStack({ flows })` sources, exported stacks and `POST /flows` bodies, and '
+        + 'gate) — in `defineStack({ flows })` sources, exported stacks and `POST /api/v1/automation` bodies, and '
         + 'every flow row in `sys_metadata`, for an envelope with no `source` key and for a `source` '
         + '(or bare string) that is empty after trimming. ⚠️ Sweeping only the edge key leaves the '
         + 'node key unswept, and the node key is the one with no schema in front of it. For each '