wip(spec): regenerate the migration registry

Claude-Session: https://claude.ai/code/session_01Sfe5YjBLwB9J3y8fvm2xq1
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

packages/spec/src/migrations/registry.ts

@@ -9058,6 +9058,80 @@ const step18: MigrationStep = {
         + "slot phrase. A flow that boots without that warn is unaffected; every structural "
         + 'condition carrying a non-blank `source` parses byte-identically to before.',
     },
+    // The ledger `predicate` slots' half of the blank-predicate rule. A SEPARATE
+    // entry from `flow-edge-condition-evaluated-slot-source-required` on purpose:
+    // that one carries the structural slots (`edges[].condition`,
+    // `config.condition`), refused by the evaluated-slot rule under
+    // EVALUATED_EXPRESSION_SOURCE_REQUIRED, where removing a blank condition
+    // INVERTS the edge. These slots are declared `z.string()`, are refused under
+    // PREDICATE_SLOT_STRING_REFUSAL, and removing the blank is behaviour-
+    // preserving — a different prescription, which one entry cannot carry for both.
+    //
+    // No backticks in `surface` — build-upgrade-guide.ts renders it inside a code
+    // span already, and a nested backtick would close it.
+    {
+      id: 'flow-predicate-slot-blank-string-refused',
+      surface:
+        'the two ledger predicate slots on a flow node — config.conditions[].expression on a decision '
+        + 'node (a branch predicate) and config.fields[].visibleWhen on a screen node (a field visibility '
+        + 'predicate) — authored as a string that is blank after trimming (\'\', \'   \', a tab or a '
+        + 'newline), at any depth including an ADR-0031 region body. Reachable wherever a flow is '
+        + 'authored or stored: defineStack({ flows }) sources, defineFlow(), an exported stack passed to '
+        + 'objectstack validate, a POST /flows body, and a flow row already sitting in sys_metadata',
+      replacement:
+        'the predicate the branch or field was meant to test, as non-blank bare CEL text '
+        + '(`expression: \'record.amount > 10\'`, `visibleWhen: \'amount > 0\'`); or REMOVE the blank. '
+        + 'On a screen field, drop the `visibleWhen` key: an absent `visibleWhen` shows the field '
+        + 'unconditionally, which is what a blank one already did at run time (the resume contract '
+        + 'treated it as absent, and the renderer fell back to showing the field). On a decision '
+        + 'branch, drop the whole `conditions[i]` element: `expression` is required by '
+        + '`DecisionConditionSchema`, so a branch cannot keep its label without it, and a branch whose '
+        + 'predicate was blank was never taken, so dropping it changes no run. ⚠️ Removal is '
+        + 'behaviour-preserving HERE, unlike on a structural condition, where dropping a blank '
+        + '`condition` turns a never-firing edge into an always-firing one '
+        + '(`flow-edge-condition-evaluated-slot-source-required`)',
+      reason:
+        'Card #17493, ruling A (5651023407). Both slots are declared bare CEL text (`z.string()`) '
+        + 'and both admitted a blank string at every door: the expression ledger resolver skipped it '
+        + 'as "not authored", and `AutomationEngine.evaluateCondition` answered it `false` — so a '
+        + 'decision branch carrying it was never taken, with nothing said at any layer, and a screen '
+        + 'field carrying it was shown with its predicate ignored. #15572 had pinned that '
+        + 'admission as correct because the two sides agreed. The ruling is that self-consistency '
+        + 'between parser and evaluator is not a defence when the author\'s intent is silently '
+        + 'dropped — the third instance of one rule, after #17322 (the structural `config.condition`) '
+        + 'and #15811 (a blank evaluated `source`). The blank is now refused at `FlowSchema.parse`, '
+        + 'at `AutomationEngine.registerFlow` (which parses first) and at `objectstack validate`, all '
+        + 'three through `predicateSlotRefusal`, leading with `PREDICATE_SLOT_STRING_REFUSAL`. '
+        + '⚠️ No D2 conversion, and the reason is the judgment this entry delegates: the blank is '
+        + 'where an author meant to write a rule, and the platform cannot tell a predicate somebody '
+        + 'forgot from one they meant to delete. Removing it preserves what ran; writing it is what '
+        + 'the author intended; only the author knows which. '
+        + '⚠️ A flow ALREADY STORED with such a blank no longer registers at all, not just that '
+        + 'branch or field: `registerFlow` parses through `canonicalizeStoredFlow` → '
+        + '`FlowSchema.parse`, and each boot path in `service-automation/src/plugin.ts` logs one '
+        + '`warn` naming the flow and continues — its trigger is never armed. '
+        + 'ADR-0087, ADR-0032.',
+      acceptanceCriteria:
+        'Grep every flow node in `defineStack({ flows })` sources, exported stacks, `POST /flows` '
+        + 'bodies and every flow row in `sys_metadata` — including nodes inside a `loop` / '
+        + '`parallel` / `try_catch` region body — for a `decision` node whose '
+        + '`config.conditions[i].expression`, or a `screen` node whose `config.fields[i].visibleWhen`, '
+        + 'is a string that is empty after trimming. Each refusal names the node and the branch or '
+        + 'field, which is the TODO\'s locator: `FlowSchema.parse` anchors a `custom` issue at '
+        + '`nodes.N.config.conditions.I.expression` (or `…config.fields.I.visibleWhen`, or the region '
+        + 'path `nodes.N.config.body.nodes.M.config…`), and `objectstack validate` prints the same '
+        + 'path; `validateStackExpressions` phrases it as '
+        + '`node \'check\' (decision) decision branch expression at config.conditions[0].expression`. '
+        + 'For each hit decide, per the `replacement` note, whether to write the predicate or to '
+        + 'remove it — and on a decision branch removing means the whole branch. Two proofs. (1) For '
+        + 'a stack authored in config files, `objectstack validate` is clean. (2) Boot the stack and '
+        + 'confirm each flow REGISTERS: no `failed to register flow` warn for it (the three boot '
+        + 'paths spell it `[Automation] failed to register flow`, `[Automation] flow re-sync: failed '
+        + 'to register flow` and `[Automation] cold-boot flow bind: failed to register flow`) — that '
+        + 'warn line is the locator for a row that exists only in `sys_metadata`. A non-blank '
+        + 'predicate parses and registers byte-identically to before, and a non-string in these '
+        + 'slots keeps its own earlier refusal (at `registerFlow` and `objectstack validate`).',
+    },
     {
       id: 'hook-register-undispatched-lifecycle-event-refused',
       surface: