diff --git a/.claude/skills/fix-issue.md b/.claude/skills/fix-issue.md
index da6f88926..73236ccbd 100644
--- a/.claude/skills/fix-issue.md
+++ b/.claude/skills/fix-issue.md
@@ -328,6 +328,7 @@ cases for these three BSON types — they fell to `default: return nil`.
 | A **Decimal/DateTime** in `dynamictext` always rendered with the hardcoded default format ("5068.38000000"); no MDL way to set the per-parameter Format, and a widget-level `decimalPrecision:` was **silently dropped** (mxcli check ✓, exec ✓, but gone) | The model always stored `ClientTemplateParameter.FormattingInfo`, but **all three writers hardcoded it** (`DecimalPrecision:2, GroupDigits:false, DateFormat:Date, EnumFormat:Text`) and ignored `param.FormattingInfo`; the grammar had no syntax to set it and DESCRIBE dropped it on read too | grammar `mdl/grammar/domains/MDLPage.g4` (`paramAssignmentV3` + `paramFormatV3`), `mdl/ast/ast_page_v3.go` (`ParamFormatV3`), `mdl/visitor/visitor_page_v3.go` (`buildParamFormatV3`), builder `mdl/executor/cmd_pages_builder_v3_widgets.go` (`formattingInfoFromParamFormat`), writers `mdl/backend/modelsdk/widget_write.go` (`formattingInfoToGen`) + `sdk/mpr/writer_widgets.go` (`serializeClientTemplateParameter`), describe `cmd_pages_describe_output.go` (`formatParamFormatSuffix`), validate `validate_widgets.go` (`validateDynamicTextFormatting`/MDL-WIDGET18) | Add a per-param `FORMAT (decimalPrecision: N, groupDigits: bool, dateFormat: …, customDateFormat: '…', enumFormat: …)` block: `{1} = Amount format (decimalPrecision: 2, groupDigits: true)`. The **FORMAT keyword is required** — a bare `(…)` after the value is ambiguous with a function call because `:` is OQL division in expressions. Writers use the param's FormattingInfo when set, else the same hardcoded defaults (nil → byte-identical to before, zero risk to existing widgets). MDL-WIDGET18 turns a widget-level format key into an actionable error (no more silent drop) and validates keys/enums. Verified: exec → `mx check` (11.12.1) 0 errors + DESCRIBE round-trip. Repro `mdl-examples/bug-tests/ledger-75-dynamictext-formatting.mdl`. Ledger #75 |
 | dynamic-text `format (…)` writes valid FormattingInfo, `mx check` ✓, but **renders unformatted** at runtime — a Decimal shows `-12` not `-12.00`, dates ignore the format | The parameter was serialized as `Expression: toString($currentObject/Attr)` (a non-String attribute was wrapped in `toString()`), and Mendix applies FormattingInfo **only to attribute-bound** params — an Expression param bypasses it. The BSON was valid but inert; `mx check` and DESCRIBE can't catch a *render* problem (the exact trap the runtime-verify skill exists for — I shipped #75 without it and the tester caught this) | `mdl/executor/cmd_pages_builder_v3.go` (`resolveTemplateAttributePathFull`, the bare-attribute branch) | Bind a bare non-String attribute as a structured **`AttributeRef`**, not a `toString()` Expression — the runtime then renders it through FormattingInfo, exactly as Studio Pro does. `toString()` was never required by mxbuild (AttributeRef for a Decimal/DateTime in a text template passes `mx check` → 0 errors). Engine read-parity holds. Note the `$param.Attr` non-String path (same function) still uses `toString()` — rarer, left for follow-up. Ledger #76 |
 | A **DataGrid2 dynamic-text column** (`column x (ShowContentAs: dynamicText, Content: '{1}', ContentParams: [{1} = Attr format (…)])`) fails to open with **CE0463**, *and* its `format (…)` block is silently dropped. `mxcli docker check` hides the CE0463 because it runs `mx update-widgets` first; raw `mx check` and `mxbuild --serve` (run --local) surface it | Two independent gaps in the full-page object-list column path. (1) The shared `buildClientTemplateParams` never read the parsed `p.Format`, and the column-scoped serializer `SerializeColumnClientTemplateParameter` **hardcoded** FormattingInfo — so a column param's format was dropped at both write points. (2) A dynamic-text column has no attribute and no content widgets, so `detectObjectListItemKind` classified it as the **default** kind, which has no empty-ClientTemplate rules → its `tooltip` serialized as `TextTemplate:null`. Studio Pro stores an **empty `Forms$ClientTemplate`** there (as for an attribute column), so the widget failed to load | `mdl/executor/cmd_pages_builder_v3_widgets.go` (`buildClientTemplateParams` → apply `formattingInfoFromParamFormat(p.Format)`), `mdl/backend/widgetobj/builder.go` (`SerializeColumnClientTemplateParameter` honours `param.FormattingInfo`; new `itemKindDynamicText` + `emptyClientTemplateRules` tooltip entry; `detectObjectListItemKind`), describe `mdl/executor/cmd_pages_describe_pluggable.go` (`extractTextTemplateParameters` zips the format suffix) | Route the FORMAT block through the *shared* params helper (fixes the object-list column path **and** the ALTER PAGE column path at once) and stop hardcoding FormattingInfo in the column serializer. Classify a `showContentAs: dynamicText` column as its own item kind and give it the attribute column's `tooltip → empty CT` rule (exportValue stays null). **Diagnosis method that found the CE0463**: `update-widgets` on a *copy* cleared it → Case B (our BSON); a path-level flatten-diff of the datagrid subtree, mine vs the reconciled reference, isolated the single differing path `columns[dynamicText]/tooltip/TextTemplate` null↔empty. **Trap**: `docker check`'s built-in `update-widgets` masks the very defect you're hunting — measure with raw `mx check` or the serve build. Repro `mdl-examples/bug-tests/ledger-77-datagrid-dynamictext-column.mdl`; verified end-to-end (raw `mx check` 0 errors + Playwright cell renders `-1,234.50`). Ledger #77 |
+| A workflow **`DECISION`** whose expression uses the documented lowercase `$workflowContext` fails `mx check` with **`[error] [CE0117] "Error(s) in expression." at Decision 'Decision'`**, while the *same spelling* in a `CALL MICROFLOW … WITH` clause works. `mxcli check` and `mxcli exec` both report success | The context parameter is named `WorkflowContext` and Mendix expressions are case-sensitive on 11.9+, so `$workflowContext` is an undefined variable. `normalizeWorkflowContextExpr` existed and was well-tested, but was only *applied* in `autoBindCallMicroflow` (the FINDINGS #39 fix) — `buildExclusiveSplit` stored `n.Expression` verbatim. The working WITH clause is what disguised it: the user reasonably concludes the spelling is fine | `mdl/executor/cmd_workflows_write.go` (`buildExclusiveSplit`, and the sibling `buildWaitForTimer` whose delay may reference a context date attribute) | Run the authored expression through the existing `normalizeWorkflowContextExpr` at every site that accepts a user expression — there are three in the workflow writer, and only the parameter-mapping one was covered. **Generalisable — the shape to look for**: a *normalizer that exists and is unit-tested* is not evidence it is *called*; grep the call sites, not the helper. When one input spelling works and an identical one fails, compare the two code paths before questioning the data. **Also fix the docs that teach the broken form** — `.claude/skills/mendix/write-workflows.md` showed lowercase in its DECISION example and is synced into user projects by `mxcli init` via `cmd/mxcli/skills/`, so the bug propagated to every generated project. Repro `mdl-examples/bug-tests/845-workflow-decision-context-casing.mdl`; verified end-to-end (`mx check` 11.13.0: 1 error → 0). Issue #845 |
 
 **Key insight:** `microflows$ListRange` stores offset/limit inside a nested
 `CustomRange` map — must cast `raw["CustomRange"].(map[string]any)` before
diff --git a/.claude/skills/mendix/write-workflows.md b/.claude/skills/mendix/write-workflows.md
index da27bcb90..0c2549faf 100644
--- a/.claude/skills/mendix/write-workflows.md
+++ b/.claude/skills/mendix/write-workflows.md
@@ -69,10 +69,10 @@ begin
 
   -- Call a microflow (server logic); optional parameter mapping + outcomes
   call microflow Module.ACT_Validate
-    with (Module.ACT_Validate.Item = '$workflowContext');
+    with (Module.ACT_Validate.Item = '$WorkflowContext');
 
   -- Decision: a boolean or enum exclusive split
-  decision '$workflowContext/Total > 1000'
+  decision '$WorkflowContext/Total > 1000'
     outcomes
       true  -> { call microflow Module.ACT_Escalate; }
       false -> { call microflow Module.ACT_AutoApprove; };
@@ -182,6 +182,9 @@ documented in `system-module.md`.
 - A user task / decision with a single outcome and no activity can trip
   `CE1876` — give each branch a body or a distinct outcome.
 - The context **Parameter entity must be persistent**.
+- Write the context variable as **`$WorkflowContext`**, matching the parameter
+  name exactly. Mendix expressions are case-sensitive on 11.9+, so a lowercase
+  `$workflowContext` is an undefined variable and yields `CE0117`.
 
 ## Validate before presenting
 
diff --git a/mdl-examples/bug-tests/845-workflow-decision-context-casing.mdl b/mdl-examples/bug-tests/845-workflow-decision-context-casing.mdl
new file mode 100644
index 000000000..eab949f4b
--- /dev/null
+++ b/mdl-examples/bug-tests/845-workflow-decision-context-casing.mdl
@@ -0,0 +1,47 @@
+-- Bug #845: workflow DECISION expressions were not case-normalized.
+--
+-- The workflow context parameter is stored as "WorkflowContext". Mendix
+-- expressions are case-sensitive on 11.9+, so a user-written `$workflowContext`
+-- is an undefined variable. CALL MICROFLOW `WITH` expressions were already
+-- normalized (FINDINGS #39), but DECISION expressions were stored verbatim:
+--
+--   "Expression": "$workflowContext/IsExclusive"
+--
+-- mx check then reported, against an otherwise clean project:
+--
+--   [error] [CE0117] "Error(s) in expression." at Decision 'Decision'
+--
+-- The inconsistency is what hid the bug — the same spelling works in a WITH
+-- clause and fails in a DECISION. The shipped write-workflows skill documented
+-- the lowercase form in its DECISION example, so following the docs produced a
+-- project that would not build.
+--
+-- Fix: buildExclusiveSplit (and its sibling buildWaitForTimer, whose delay may
+-- reference a context date attribute) run the authored expression through
+-- normalizeWorkflowContextExpr, the same helper autoBindCallMicroflow uses.
+--
+-- Manual verification (needs a project, so `make check-mdl` only syntax-checks this):
+--
+--   mxcli exec 845-workflow-decision-context-casing.mdl -p app.mpr
+--   mx check -p app.mpr
+--
+-- Expect 0 errors. Before the fix this produced CE0117 on the decision.
+
+create module Issue845;
+create module role Issue845.User;
+
+@position(100, 100)
+create persistent entity Issue845.Ctx (
+  IsExclusive: boolean,
+  Total: decimal
+);
+
+-- Lowercase on purpose: this is the form the docs used to show.
+create workflow Issue845."WF_DecisionCasing"
+  parameter $WorkflowContext: Issue845.Ctx
+begin
+  decision '$workflowContext/IsExclusive'
+    outcomes
+      true  -> { }
+      false -> { };
+end workflow;
diff --git a/mdl/executor/cmd_workflows_decision_test.go b/mdl/executor/cmd_workflows_decision_test.go
new file mode 100644
index 000000000..aae6c9904
--- /dev/null
+++ b/mdl/executor/cmd_workflows_decision_test.go
@@ -0,0 +1,46 @@
+package executor
+
+import (
+	"testing"
+
+	"github.com/mendixlabs/mxcli/mdl/ast"
+)
+
+// TestBuildExclusiveSplit_NormalizesWorkflowContext guards issue #845.
+//
+// The workflow context parameter is stored as "WorkflowContext", and Mendix
+// expressions are case-sensitive on 11.9+, so a user-written `$workflowContext`
+// is an undefined variable. autoBindCallMicroflow already normalizes CALL
+// MICROFLOW `WITH` expressions (FINDINGS #39), but DECISION expressions were
+// stored verbatim, so the lowercase form reached the .mpr and mx check reported
+//
+//	[error] [CE0117] "Error(s) in expression." at Decision 'Decision'
+//
+// The inconsistency is what made this hard to spot: the same `$workflowContext`
+// spelling works in a WITH clause and fails in a DECISION.
+func TestBuildExclusiveSplit_NormalizesWorkflowContext(t *testing.T) {
+	cases := map[string]string{
+		"$workflowContext/IsExclusive": "$WorkflowContext/IsExclusive",
+		"$WORKFLOWCONTEXT/Total > 100": "$WorkflowContext/Total > 100",
+		"$WorkflowContext/IsExclusive": "$WorkflowContext/IsExclusive",
+		"$Other/Field":                 "$Other/Field",
+	}
+	for in, want := range cases {
+		act := buildExclusiveSplit(&ast.WorkflowDecisionNode{Expression: in})
+		if act.Expression != want {
+			t.Errorf("buildExclusiveSplit(%q).Expression = %q, want %q", in, act.Expression, want)
+		}
+	}
+}
+
+// TestBuildWaitForTimer_NormalizesWorkflowContext covers the same defect in the
+// sibling expression site: a WAIT FOR TIMER delay may reference a date attribute
+// on the workflow context, and was likewise stored verbatim.
+func TestBuildWaitForTimer_NormalizesWorkflowContext(t *testing.T) {
+	act := buildWaitForTimer(&ast.WorkflowWaitForTimerNode{
+		DelayExpression: "$workflowContext/DueDate",
+	})
+	if want := "$WorkflowContext/DueDate"; act.DelayExpression != want {
+		t.Errorf("buildWaitForTimer.DelayExpression = %q, want %q", act.DelayExpression, want)
+	}
+}
diff --git a/mdl/executor/cmd_workflows_write.go b/mdl/executor/cmd_workflows_write.go
index 1cad00368..2247c35fe 100644
--- a/mdl/executor/cmd_workflows_write.go
+++ b/mdl/executor/cmd_workflows_write.go
@@ -355,7 +355,10 @@ func buildCallWorkflowActivity(n *ast.WorkflowCallWorkflowNode) *workflows.CallW
 func buildExclusiveSplit(n *ast.WorkflowDecisionNode) *workflows.ExclusiveSplitActivity {
 	act := &workflows.ExclusiveSplitActivity{}
 	act.ID = model.ID(generateWorkflowUUID())
-	act.Expression = n.Expression
+	// Same case-sensitivity trap as CALL MICROFLOW parameter mappings (#845):
+	// the context parameter is named "WorkflowContext", so a user-written
+	// `$workflowContext` is an undefined variable and mx check reports CE0117.
+	act.Expression = normalizeWorkflowContextExpr(n.Expression)
 	act.Caption = n.Caption
 
 	if act.Caption == "" {
@@ -459,7 +462,8 @@ func buildJumpTo(n *ast.WorkflowJumpToNode) *workflows.JumpToActivity {
 func buildWaitForTimer(n *ast.WorkflowWaitForTimerNode) *workflows.WaitForTimerActivity {
 	act := &workflows.WaitForTimerActivity{}
 	act.ID = model.ID(generateWorkflowUUID())
-	act.DelayExpression = n.DelayExpression
+	// A delay may reference a date attribute on the workflow context (#845).
+	act.DelayExpression = normalizeWorkflowContextExpr(n.DelayExpression)
 	act.Caption = n.Caption
 
 	if act.Caption == "" {