diff --git a/apps/desktop/src/lib/mongo/mongoCompletion.ts b/apps/desktop/src/lib/mongo/mongoCompletion.ts
index f3085a4e02..0c9a7930fd 100644
--- a/apps/desktop/src/lib/mongo/mongoCompletion.ts
+++ b/apps/desktop/src/lib/mongo/mongoCompletion.ts
@@ -1043,6 +1043,11 @@ function collectInnermostObjectKeys(text: string, cursor: number, stack: MongoCo
 function isExpressionArray(scan: MongoCallScan): boolean {
   const inner = innermost(scan);
   if (inner?.kind !== "array") return false;
+  if (inner.key === "branches") {
+    // Only `$switch.branches` is a case list; any other `branches` array is a plain expression array.
+    const parent = scan.stack[scan.stack.length - 2];
+    if (parent?.kind === "object" && parent.key === "$switch") return false;
+  }
   if (inner.key?.startsWith("$")) return true;
   for (let i = scan.stack.length - 1; i >= 0; i--) {
     const container = scan.stack[i];
@@ -1052,6 +1057,49 @@ function isExpressionArray(scan: MongoCallScan): boolean {
   return false;
 }
 
+const EXPRESSION_OPERATOR_VALUE_ENUMS: Record<string, Record<string, string>> = {
+  $regexMatch: { options: "$options" },
+  $regexFind: { options: "$options" },
+  $regexFindAll: { options: "$options" },
+  $dateToParts: { iso8601: "boolean" },
+};
+
+function isSwitchBranch(scan: MongoCallScan): boolean {
+  const n = scan.stack.length;
+  if (n < 3) return false;
+  const inner = scan.stack[n - 1];
+  const parent = scan.stack[n - 2];
+  const grandParent = scan.stack[n - 3];
+  return inner?.kind === "object" && parent?.kind === "array" && parent.key === "branches" && grandParent?.kind === "object" && grandParent.key === "$switch";
+}
+
+function classifyExpressionCursor(scan: MongoCallScan, rootKey?: string): MongoCursorClass {
+  if (isSwitchBranch(scan)) {
+    if (scan.inValue) return { mode: "fieldRef" };
+    return { mode: "operatorField", operator: "switchBranch" };
+  }
+
+  if (isExpressionArray(scan)) return { mode: "fieldRef" };
+
+  const inner = innermost(scan);
+  if (!inner) return { mode: "none" };
+
+  if (scan.inValue) {
+    const parentOp = inner.key ?? "";
+    const enumKey = EXPRESSION_OPERATOR_VALUE_ENUMS[parentOp]?.[scan.valueKey ?? ""];
+    if (enumKey) return { mode: "enumValue", enumKey };
+    return { mode: "fieldRef" };
+  }
+
+  if (inner.kind !== "object") return { mode: "none" };
+
+  if (inner.key && inner.key !== rootKey && (inner.key in OPERATOR_SUB_KEYS || inner.key.startsWith("$"))) {
+    return { mode: "operatorField", operator: inner.key };
+  }
+
+  return { mode: "expression" };
+}
+
 function collectScopeVariables(scan: MongoCallScan): string[] {
   const vars = new Set<string>();
 
@@ -1172,10 +1220,7 @@ function classifyFilter(scan: MongoCallScan, rootIndex: number): MongoCursorClas
   // Under `$expr` the vocabulary is aggregation expressions.
   const exprIndex = findContainerIndex(scan, rootIndex, "$expr");
   if (exprIndex >= 0) {
-    if (isExpressionArray(scan)) return { mode: "fieldRef" };
-    if (scan.inValue) return { mode: "fieldRef" };
-    if (inner.kind === "object") return { mode: "expression" };
-    return { mode: "none" };
+    return classifyExpressionCursor(scan, "$expr");
   }
 
   if (inner.kind === "array") {
@@ -1352,13 +1397,14 @@ const OPTION_COLLECTION_KEYS: Record<string, ReadonlySet<string>> = {
 };
 
 /** Option keys whose value is a filter document. */
-const FILTER_OPTION_KEYS = new Set(["partialFilterExpression", "validator"]);
+const FILTER_OPTION_KEYS = new Set(["partialFilterExpression", "validator", "filter", "query", "updates", "deletes"]);
 
 /** Option keys whose value is a document with its own fixed keys, and the value sets inside it. */
 const SUB_DOCUMENT_OPTION_KEYS: Record<string, Record<string, string>> = {
   collation: { locale: "locale", caseFirst: "caseFirst", alternate: "alternate", maxVariable: "maxVariable", strength: "strength" },
   timeseries: { granularity: "granularity" },
   clusteredIndex: {},
+  roles: { role: "builtInRole" },
 };
 
 function classifyMethodOptions(method: string, scan: MongoCallScan): MongoCursorClass {
@@ -1405,8 +1451,15 @@ function classifyCollation(scan: MongoCallScan, rootIndex: number): MongoCursorC
 /** A one-level document with a fixed key set (`OPERATOR_SUB_KEYS[operator]`) and, for some keys, a fixed value set. */
 function classifySubDocument(scan: MongoCallScan, rootIndex: number, operator: string, valueEnums: Record<string, string>): MongoCursorClass {
   const inner = innermost(scan);
-  if (!inner || inner.kind !== "object" || innerDepth(scan, rootIndex) !== 0) return { mode: "none" };
+  const depth = innerDepth(scan, rootIndex);
+  if (!inner || inner.kind !== "object") return { mode: "none" };
+
+  // Allow depth 0 (direct object) or depth 1 (array of objects)
+  if (depth > 1) return { mode: "none" };
+  if (depth === 1 && scan.stack[scan.stack.length - 2]?.kind !== "array") return { mode: "none" };
+
   if (scan.inValue) {
+    if (operator === "roles" && scan.valueKey === "db") return { mode: "database" };
     const enumKey = valueEnums[scan.valueKey ?? ""];
     return enumKey ? { mode: "enumValue", enumKey } : { mode: "none" };
   }
@@ -1540,43 +1593,46 @@ function stageStringValueMode(stage: string): MongoCompletionMode {
 
 function classifyStageBody(stage: string, scan: MongoCallScan, bodyIndex: number): MongoCursorClass {
   if (stage === "$match") return { ...classifyFilter(scan, bodyIndex), stage };
-  if (stage === "$group") return { mode: classifyGroup(scan, bodyIndex), stage };
+  if (stage === "$group") return { ...classifyGroup(scan, bodyIndex), stage };
   if (stage === "$sort") return { ...classifyKeyMap(scan, bodyIndex, "sort"), stage };
   if (stage === "$unset") return { mode: innermost(scan)?.kind === "array" ? "fieldPath" : "none", stage };
   if (OPTION_STAGES.has(stage)) return classifyStageOptions(stage, scan, bodyIndex);
   // `$project`-shaped stages and anything unmodelled: keys are field names, values are expressions.
-  return { mode: classifyProjection(scan, bodyIndex), stage };
+  return { ...classifyProjection(scan, bodyIndex), stage };
 }
 
-function classifyGroup(scan: MongoCallScan, bodyIndex: number): MongoCompletionMode {
+function classifyGroup(scan: MongoCallScan, bodyIndex: number): MongoCursorClass {
   const depth = innerDepth(scan, bodyIndex);
-  if (depth < 0) return "none";
+  if (depth < 0) return { mode: "none" };
 
   if (depth === 0) {
-    // `{ $group: { _id: … , total: … } }` — keys are output names, `_id` is required.
-    if (!scan.inValue) return "field";
-    return scan.valueKey === "_id" ? "fieldRef" : "none";
+    if (scan.inValue) return { mode: "fieldRef" };
+    return { mode: innermost(scan)?.kind === "object" ? "field" : "none" };
   }
 
-  if (scan.inValue) return "fieldRef";
-
-  const inner = innermost(scan);
-  if (isExpressionArray(scan)) return "fieldRef";
-  if (inner?.kind !== "object") return "none";
   // One level in: `_id: { … }` builds a compound key, anything else is an accumulator.
-  if (depth === 1) return inner.key === "_id" ? "expression" : "accumulator";
-  return "expression";
+  if (depth === 1) {
+    const inner = innermost(scan);
+    if (inner?.kind === "array" && isExpressionArray(scan)) return classifyExpressionCursor(scan);
+    if (inner?.kind !== "object") return { mode: "none" };
+    if (scan.inValue) return { mode: "fieldRef" };
+    if (inner.key === "_id") return { mode: "expression" };
+    return { mode: "accumulator" };
+  }
+
+  return classifyExpressionCursor(scan);
 }
 
-function classifyProjection(scan: MongoCallScan, bodyIndex: number): MongoCompletionMode {
+function classifyProjection(scan: MongoCallScan, bodyIndex: number): MongoCursorClass {
   const depth = innerDepth(scan, bodyIndex);
-  if (depth < 0) return "none";
-  if (scan.inValue) return "fieldRef";
+  if (depth < 0) return { mode: "none" };
 
-  const inner = innermost(scan);
-  if (isExpressionArray(scan)) return "fieldRef";
-  if (inner?.kind !== "object") return "none";
-  return depth === 0 ? "field" : "expression";
+  if (depth === 0) {
+    if (scan.inValue) return { mode: "fieldRef" };
+    return { mode: innermost(scan)?.kind === "object" ? "field" : "none" };
+  }
+
+  return classifyExpressionCursor(scan);
 }
 
 function classifyStageOptions(stage: string, scan: MongoCallScan, bodyIndex: number): MongoCursorClass {
@@ -1628,9 +1684,7 @@ function classifyStageOptions(stage: string, scan: MongoCallScan, bodyIndex: num
         if (!scan.inValue) return { mode: "windowOperator", stage };
         return { mode: "fieldRef", stage };
       }
-      if (scan.inValue) return { mode: "fieldRef", stage };
-      if (isExpressionArray(scan)) return { mode: "fieldRef", stage };
-      return { mode: innermost(scan)?.kind === "object" ? "expression" : "none", stage };
+      return { ...classifyExpressionCursor(scan), stage };
     }
 
     if (stage === "$fill") {
@@ -1662,9 +1716,7 @@ function classifyStageOptions(stage: string, scan: MongoCallScan, bodyIndex: num
     if (innermost(scan)?.kind === "array") return { mode: "fieldPath", stage };
   }
 
-  if (scan.inValue) return { mode: "fieldRef", stage };
-  if (isExpressionArray(scan)) return { mode: "fieldRef", stage };
-  return { mode: innermost(scan)?.kind === "object" ? "expression" : "none", stage };
+  return { ...classifyExpressionCursor(scan), stage };
 }
 
 /* ------------------------------------------------------------------ *
@@ -2148,20 +2200,61 @@ function matchCursorMethodDot(beforeCursor: string): { find: boolean; countable:
   const chain = beforeCursor.slice(closeParen + 1);
   if (!/\.\s*[\w$-]*$/.test(chain)) return null;
 
+  let pos = closeParen + 1;
+  let isCountable = true;
+  let isTerminal = false;
   const isFind = lastMatch[1] === "find";
-  if (/\.\s*(?:count|explain)\s*\([^()]*\)/.test(chain)) {
+  const validMethods = isFind ? ["sort", "skip", "limit", "collation", "toArray", "pretty", "hint", "batchSize", "maxTimeMS", "comment"] : ["toArray", "pretty"];
+
+  while (pos < beforeCursor.length) {
+    const nextDot = beforeCursor.indexOf(".", pos);
+    if (nextDot === -1) break;
+
+    const afterDot = beforeCursor.slice(nextDot + 1);
+    const methodMatch = afterDot.match(/^\s*([\w$]+)\s*\(/);
+
+    // If there's no next method call but there is a dot, we are typing the next method name.
+    if (!methodMatch) {
+      if (/^\s*[\w$-]*$/.test(afterDot)) {
+        // Typing the method.
+        break;
+      } else {
+        // Something else, invalid chain.
+        return null;
+      }
+    }
+
+    const methodName = methodMatch[1];
+    const methodOpenParen = nextDot + 1 + methodMatch[0].length - 1;
+    const methodCloseParen = findMatchingParen(beforeCursor, methodOpenParen);
+
+    if (methodName === "count" || methodName === "explain") {
+      isTerminal = true;
+    } else if (!validMethods.includes(methodName)) {
+      return null;
+    } else {
+      // Any method chained between find() and the cursor breaks the bare find() count() parses on.
+      isCountable = false;
+    }
+
+    if (methodCloseParen === -1) {
+      // Incomplete method arguments, so we aren't typing a method dot
+      return null;
+    }
+
+    pos = methodCloseParen + 1;
+  }
+
+  if (isTerminal) {
     return { find: isFind, countable: false, terminal: true };
   }
 
-  if (isFind) {
-    if (!/^(?:\s*\.\s*(?:sort|skip|limit|collation|toArray|pretty)\s*\([^()]*\))*\s*\.\s*[\w$-]*$/.test(chain)) return null;
-    return { find: true, countable: /^\s*\.\s*[\w$-]*$/.test(chain) };
+  if (!isFind) {
+    return { find: false, countable: false };
   }
 
-  if (!/^(?:\s*\.\s*(?:toArray|pretty)\s*\([^()]*\))*\s*\.\s*[\w$-]*$/.test(chain)) {
-    return { find: false, countable: false, terminal: true };
-  }
-  return { find: false, countable: false };
+  // Countable only while no method call has been walked since find().
+  return { find: true, countable: isCountable };
 }
 
 /**
diff --git a/apps/desktop/src/lib/mongo/mongoCompletionTables.ts b/apps/desktop/src/lib/mongo/mongoCompletionTables.ts
index 67775bbec5..35d3adfa6b 100644
--- a/apps/desktop/src/lib/mongo/mongoCompletionTables.ts
+++ b/apps/desktop/src/lib/mongo/mongoCompletionTables.ts
@@ -56,6 +56,7 @@ export const FIELD_QUERY_OPERATORS: MongoOperatorSpec[] = specs([
   ["$exists", "Matches documents that have the field", "$exists: true"],
   ["$type", "Matches documents by BSON type", '$type: "${string}"'],
   ["$regex", "Matches a regular expression", '$regex: "${pattern}"'],
+  ["$options", "Regular expression options", '$options: "${i}"'],
   ["$mod", "Matches values by modulo division", "$mod: [${divisor}, ${remainder}]"],
   ["$all", "Matches arrays containing all the values", "$all: [${}]"],
   ["$elemMatch", "Matches arrays with an element matching all criteria", "$elemMatch: { ${} }"],
@@ -329,6 +330,11 @@ export const EXPRESSION_OPERATORS: MongoOperatorSpec[] = specs([
   ["$isoWeek", "ISO week number of a date", '$isoWeek: "$${field}"'],
   ["$isoWeekYear", "ISO week-numbering year of a date", '$isoWeekYear: "$${field}"'],
   ["$isoDayOfWeek", "ISO day of the week of a date", '$isoDayOfWeek: "$${field}"'],
+  // Bitwise
+  ["$bitAnd", "Returns the bitwise AND of an array of numbers", "$bitAnd: [${}]"],
+  ["$bitOr", "Returns the bitwise OR of an array of numbers", "$bitOr: [${}]"],
+  ["$bitXor", "Returns the bitwise XOR of an array of numbers", "$bitXor: [${}]"],
+  ["$bitNot", "Returns the bitwise NOT of a number", "$bitNot: ${}"],
   // Types and misc
   ["$type", "Returns the BSON type of a value", "$type: ${}"],
   ["$convert", "Converts a value to a given type", '$convert: { input: ${}, to: "${string}" }'],
@@ -426,6 +432,10 @@ const JSON_SCHEMA_KEYWORDS: Spec[] = [
  * object of the update operator.
  */
 export const OPERATOR_SUB_KEYS: Record<string, MongoOperatorSpec[]> = {
+  roles: specs([
+    ["role", "Name of the role", 'role: "${read}"'],
+    ["db", "Database on which the role is granted", 'db: "${admin}"'],
+  ]),
   $text: specs([
     ["$search", "Words or phrases to search for", '$search: "${text}"'],
     ["$language", "Language for stemming and stop words", '$language: "${en}"'],
@@ -480,6 +490,96 @@ export const OPERATOR_SUB_KEYS: Record<string, MongoOperatorSpec[]> = {
     ["value", "Value or expression to fill with", "value: ${}"],
     ["method", "Fill method", 'method: "${linear}"'],
   ]),
+  $dateToString: specs([
+    ["date", "Date to format", 'date: "$${field}"'],
+    ["format", "Format specification string", 'format: "${%Y-%m-%d}"'],
+    ["timezone", "Timezone for formatting", 'timezone: "${UTC}"'],
+    ["onNull", "Value to return if date is null or missing", "onNull: ${}"],
+  ]),
+  $dateFromParts: specs([
+    ["year", "Calendar year", "year: ${}"],
+    ["month", "Month of year (1-12)", "month: ${}"],
+    ["day", "Day of month (1-31)", "day: ${}"],
+    ["hour", "Hour of day (0-23)", "hour: ${}"],
+    ["minute", "Minute of hour (0-59)", "minute: ${}"],
+    ["second", "Second of minute (0-59)", "second: ${}"],
+    ["millisecond", "Millisecond of second (0-999)", "millisecond: ${}"],
+    ["timezone", "Timezone for formatting", 'timezone: "${UTC}"'],
+    ["isoWeekYear", "ISO week-numbering year", "isoWeekYear: ${}"],
+    ["isoWeek", "ISO week number (1-53)", "isoWeek: ${}"],
+    ["isoDayOfWeek", "Day of week (1-7, Monday is 1)", "isoDayOfWeek: ${}"],
+  ]),
+  $dateToParts: specs([
+    ["date", "Date to convert to parts", 'date: "$${field}"'],
+    ["timezone", "Timezone for calculation", 'timezone: "${UTC}"'],
+    ["iso8601", "Whether to return ISO week date parts", "iso8601: true"],
+  ]),
+  $trim: specs([
+    ["input", "String to trim", 'input: "$${field}"'],
+    ["chars", "Characters to trim", 'chars: "${ }"'],
+  ]),
+  $ltrim: specs([
+    ["input", "String to trim", 'input: "$${field}"'],
+    ["chars", "Characters to trim", 'chars: "${ }"'],
+  ]),
+  $rtrim: specs([
+    ["input", "String to trim", 'input: "$${field}"'],
+    ["chars", "Characters to trim", 'chars: "${ }"'],
+  ]),
+  $replaceOne: specs([
+    ["input", "String to search in", 'input: "$${field}"'],
+    ["find", "String or regex to search for", 'find: "${find}"'],
+    ["replacement", "String to replace with", 'replacement: "${replacement}"'],
+  ]),
+  $replaceAll: specs([
+    ["input", "String to search in", 'input: "$${field}"'],
+    ["find", "String or regex to search for", 'find: "${find}"'],
+    ["replacement", "String to replace with", 'replacement: "${replacement}"'],
+  ]),
+  $regexMatch: specs([
+    ["input", "String to evaluate", 'input: "$${field}"'],
+    ["regex", "Regular expression to match", 'regex: "${pattern}"'],
+    ["options", "Regular expression options", 'options: "${i}"'],
+  ]),
+  $regexFind: specs([
+    ["input", "String to evaluate", 'input: "$${field}"'],
+    ["regex", "Regular expression to match", 'regex: "${pattern}"'],
+    ["options", "Regular expression options", 'options: "${i}"'],
+  ]),
+  $regexFindAll: specs([
+    ["input", "String to evaluate", 'input: "$${field}"'],
+    ["regex", "Regular expression to match", 'regex: "${pattern}"'],
+    ["options", "Regular expression options", 'options: "${i}"'],
+  ]),
+  $filter: specs([
+    ["input", "Array expression to filter", 'input: "$${field}"'],
+    ["as", "Variable name for each element", 'as: "${item}"'],
+    ["cond", "Boolean expression for each element", "cond: ${}"],
+    ["limit", "Maximum number of elements to return", "limit: ${}"],
+  ]),
+  $map: specs([
+    ["input", "Array expression to transform", 'input: "$${field}"'],
+    ["as", "Variable name for each element", 'as: "${item}"'],
+    ["in", "Expression applied to each element", "in: ${}"],
+  ]),
+  $reduce: specs([
+    ["input", "Array expression to reduce", 'input: "$${field}"'],
+    ["initialValue", "Initial value of the accumulator", "initialValue: ${}"],
+    ["in", "Expression applied to each element", "in: ${}"],
+  ]),
+  $cond: specs([
+    ["if", "Condition to evaluate", "if: ${}"],
+    ["then", "Result if condition is true", "then: ${}"],
+    ["else", "Result if condition is false", "else: ${}"],
+  ]),
+  $switch: specs([
+    ["branches", "Array of case-then branch documents", "branches: [{ case: ${}, then: ${} }]"],
+    ["default", "Default expression if no branch matches", "default: ${}"],
+  ]),
+  switchBranch: specs([
+    ["case", "Condition expression to evaluate", "case: ${}"],
+    ["then", "Result expression when case is true", "then: ${}"],
+  ]),
 };
 
 const BSON_TYPE_ALIASES: Spec[] = [
@@ -509,6 +609,24 @@ const BSON_TYPE_ALIASES: Spec[] = [
  * gets a well-formed literal; numbers do not.
  */
 export const ENUM_VALUES: Record<string, MongoOperatorSpec[]> = {
+  builtInRole: specs([
+    ["read", "Provides reading data on all non-system collections", '"read"'],
+    ["readWrite", "Provides all the privileges of the read role plus ability to modify data", '"readWrite"'],
+    ["dbAdmin", "Provides administrative tasks such as schema-related tasks", '"dbAdmin"'],
+    ["dbOwner", "Provides all privileges of readWrite, dbAdmin, and userAdmin", '"dbOwner"'],
+    ["userAdmin", "Provides ability to create and modify roles and users on the current database", '"userAdmin"'],
+    ["clusterAdmin", "Provides highest cluster-level administrative privileges", '"clusterAdmin"'],
+    ["clusterManager", "Provides management and monitoring actions", '"clusterManager"'],
+    ["clusterMonitor", "Provides read-only access to monitoring tools", '"clusterMonitor"'],
+    ["hostManager", "Provides ability to monitor and manage servers", '"hostManager"'],
+    ["backup", "Provides privileges needed to back up data", '"backup"'],
+    ["restore", "Provides privileges needed to restore data", '"restore"'],
+    ["readAnyDatabase", "Provides the same privileges as read on all databases except local and config", '"readAnyDatabase"'],
+    ["readWriteAnyDatabase", "Provides the same privileges as readWrite on all databases except local and config", '"readWriteAnyDatabase"'],
+    ["userAdminAnyDatabase", "Provides the same privileges as userAdmin on all databases except local and config", '"userAdminAnyDatabase"'],
+    ["dbAdminAnyDatabase", "Provides the same privileges as dbAdmin on all databases except local and config", '"dbAdminAnyDatabase"'],
+    ["root", "Provides access to the operations and all the resources of the readWriteAnyDatabase, dbAdminAnyDatabase, userAdminAnyDatabase, clusterAdmin, restore, and backup combined", '"root"'],
+  ]),
   $type: specs(BSON_TYPE_ALIASES),
   bsonType: specs(BSON_TYPE_ALIASES),
   $options: specs([
diff --git a/packages/app-tests/mongoCompletion.test.ts b/packages/app-tests/mongoCompletion.test.ts
index 5c1a706902..43ff1acf46 100644
--- a/packages/app-tests/mongoCompletion.test.ts
+++ b/packages/app-tests/mongoCompletion.test.ts
@@ -237,6 +237,23 @@ test("recognises toArray and pretty in find chains and keeps count restricted",
   assert.deepEqual(labels("db.characters.find({}).sort({ name: 1 }).toArray()."), expectedChainMethods);
 });
 
+test("matches cursor chains across nested parentheses in arguments", () => {
+  const expectedChainMethods = ["limit", "sort", "skip", "explain", "collation", "toArray", "pretty"];
+  assert.deepEqual(labels("db.characters.find({}).sort({ x: Math.max(1, 2) })."), expectedChainMethods);
+  assert.deepEqual(labels("db.characters.find({ ratio: Math.min(a, b) }).limit(Math.max(1, 5))."), expectedChainMethods);
+});
+
+test("keeps cursor method completion anchored to a dot in the chain", () => {
+  // A completed call without a trailing dot is not a method-dot position.
+  assert.equal(labels("db.characters.find()").includes("limit"), false);
+  assert.equal(labels("db.characters.find({});").includes("limit"), false);
+  assert.equal(labels("db.characters.find() show col").includes("limit"), false);
+});
+
+test("completes field refs inside compound $group _id arrays", () => {
+  assert.ok(labels('db.users.aggregate([{ $group: { _id: [ "$', { fields }).includes("$name"));
+});
+
 test("stops offering root snippets after terminal cursor methods count and explain", () => {
   // Nothing can follow count() or explain(); these positions must yield mode "none" rather than root db.* snippets.
   assert.equal(getMongoCompletionContext("db.users.find({}).count().", "db.users.find({}).count().".length).mode, "none");
@@ -426,7 +443,7 @@ test("offers whole-filter operators at the top level and field operators under a
   assert.ok(under.includes("$oid"));
   assert.equal(under.includes("$or"), false, "$or is not valid under a field");
   assert.equal(under.includes("$and"), false);
-  assert.deepEqual(labels("db.users.find({ _id: { $o", { fields }), ["$oid"]);
+  assert.deepEqual(labels("db.users.find({ _id: { $o", { fields }), ["$options", "$oid"]);
 
   // Fields lead when nothing has been typed yet.
   const bare = labels("db.users.find({ ", { fields });
@@ -1537,6 +1554,24 @@ test("every suggested sub-document key and enumerated value parses in the positi
     clusteredIndex: (body) => `db.createCollection("x", { clusteredIndex: { ${body} } })`,
     range: (body) => `db.users.aggregate([{ $densify: { field: "t", range: { ${body} } } }])`,
     fillOutput: (body) => `db.users.aggregate([{ $fill: { output: { score: { ${body} } } } }])`,
+    roles: (body) => `db.createUser({ user: "x", pwd: "y", roles: [ { ${body} } ] })`,
+    $dateToString: (body) => `db.users.aggregate([{ $project: { d: { $dateToString: { ${body} } } } }])`,
+    $dateFromParts: (body) => `db.users.aggregate([{ $project: { d: { $dateFromParts: { ${body} } } } }])`,
+    $dateToParts: (body) => `db.users.aggregate([{ $project: { d: { $dateToParts: { ${body} } } } }])`,
+    $trim: (body) => `db.users.aggregate([{ $project: { d: { $trim: { ${body} } } } }])`,
+    $ltrim: (body) => `db.users.aggregate([{ $project: { d: { $ltrim: { ${body} } } } }])`,
+    $rtrim: (body) => `db.users.aggregate([{ $project: { d: { $rtrim: { ${body} } } } }])`,
+    $replaceOne: (body) => `db.users.aggregate([{ $project: { d: { $replaceOne: { ${body} } } } }])`,
+    $replaceAll: (body) => `db.users.aggregate([{ $project: { d: { $replaceAll: { ${body} } } } }])`,
+    $regexMatch: (body) => `db.users.aggregate([{ $project: { d: { $regexMatch: { ${body} } } } }])`,
+    $regexFind: (body) => `db.users.aggregate([{ $project: { d: { $regexFind: { ${body} } } } }])`,
+    $regexFindAll: (body) => `db.users.aggregate([{ $project: { d: { $regexFindAll: { ${body} } } } }])`,
+    $filter: (body) => `db.users.aggregate([{ $project: { d: { $filter: { ${body} } } } }])`,
+    $map: (body) => `db.users.aggregate([{ $project: { d: { $map: { ${body} } } } }])`,
+    $reduce: (body) => `db.users.aggregate([{ $project: { d: { $reduce: { ${body} } } } }])`,
+    $cond: (body) => `db.users.aggregate([{ $project: { d: { $cond: { ${body} } } } }])`,
+    $switch: (body) => `db.users.aggregate([{ $project: { d: { $switch: { ${body} } } } }])`,
+    switchBranch: (body) => `db.users.aggregate([{ $project: { d: { $switch: { branches: [ { ${body} } ] } } } }])`,
   };
   for (const [operator, keys] of Object.entries(OPERATOR_SUB_KEYS)) {
     const build = keyCommands[operator];
@@ -1572,6 +1607,7 @@ test("every suggested sub-document key and enumerated value parses in the positi
     locale: (value) => `db.users.find({}).collation({ locale: ${value} })`,
     whenMatched: (value) => `db.users.aggregate([{ $merge: { into: "out", whenMatched: ${value} } }])`,
     whenNotMatched: (value) => `db.users.aggregate([{ $merge: { into: "out", whenNotMatched: ${value} } }])`,
+    builtInRole: (value) => `db.createUser({ user: "x", pwd: "y", roles: [ { role: ${value} } ] })`,
   };
   for (const [enumKey, values] of Object.entries(ENUM_VALUES)) {
     const build = valueCommands[enumKey];
@@ -2415,3 +2451,137 @@ test("preserves auto-trigger and completion for getCollection and getSiblingDB d
   assert.equal(getMongoCompletionContext(siblingGetCollectionDot, siblingGetCollectionDot.length).mode, "method");
   assert.equal(shouldAutoOpenMongoCompletion(siblingGetCollectionDot, siblingGetCollectionDot.length), true);
 });
+
+test("completes expression operator sub-document keys and enum values", () => {
+  // Sub-keys for $dateToString
+  const dateToStringKeys = labels("db.users.aggregate([{ $project: { d: { $dateToString: { ");
+  assert.ok(dateToStringKeys.includes("date"));
+  assert.ok(dateToStringKeys.includes("format"));
+  assert.ok(dateToStringKeys.includes("timezone"));
+  assert.ok(dateToStringKeys.includes("onNull"));
+
+  // Sub-keys for $dateFromParts
+  const dateFromPartsKeys = labels("db.users.aggregate([{ $project: { d: { $dateFromParts: { ");
+  assert.ok(dateFromPartsKeys.includes("year"));
+  assert.ok(dateFromPartsKeys.includes("month"));
+  assert.ok(dateFromPartsKeys.includes("day"));
+  assert.ok(dateFromPartsKeys.includes("timezone"));
+
+  // Sub-keys for $filter
+  const filterKeys = labels("db.users.aggregate([{ $project: { d: { $filter: { ");
+  assert.ok(filterKeys.includes("input"));
+  assert.ok(filterKeys.includes("as"));
+  assert.ok(filterKeys.includes("cond"));
+  assert.ok(filterKeys.includes("limit"));
+
+  // Sub-keys for $cond
+  const condKeys = labels("db.users.aggregate([{ $project: { d: { $cond: { ");
+  assert.ok(condKeys.includes("if"));
+  assert.ok(condKeys.includes("then"));
+  assert.ok(condKeys.includes("else"));
+
+  // Sub-keys for $switch
+  const switchKeys = labels("db.users.aggregate([{ $project: { d: { $switch: { ");
+  assert.ok(switchKeys.includes("branches"));
+  assert.ok(switchKeys.includes("default"));
+
+  // Sub-keys for $regexMatch
+  const regexMatchKeys = labels("db.users.aggregate([{ $project: { d: { $regexMatch: { ");
+  assert.ok(regexMatchKeys.includes("input"));
+  assert.ok(regexMatchKeys.includes("regex"));
+  assert.ok(regexMatchKeys.includes("options"));
+
+  // Enum values for options ($regexMatch, $regexFind, $regexFindAll)
+  const regexOptions = labels("db.users.aggregate([{ $project: { d: { $regexMatch: { options: ");
+  assert.ok(regexOptions.includes("i"));
+  assert.ok(regexOptions.includes("m"));
+  assert.ok(regexOptions.includes("x"));
+  assert.ok(regexOptions.includes("s"));
+  assert.ok(regexOptions.includes("u"));
+
+  const regexOptionsQuoted = labels('db.users.aggregate([{ $project: { d: { $regexMatch: { options: "');
+  assert.ok(regexOptionsQuoted.includes("i"));
+
+  // Enum values for iso8601 ($dateToParts)
+  const dateToPartsIso = labels("db.users.aggregate([{ $project: { d: { $dateToParts: { iso8601: ");
+  assert.ok(dateToPartsIso.includes("true"));
+  assert.ok(dateToPartsIso.includes("false"));
+
+  // Used key deduplication inside operator sub-documents
+  const dedupedKeys = labels("db.users.aggregate([{ $project: { d: { $dateToString: { date: '$created', ");
+  assert.equal(dedupedKeys.includes("date"), false, "already specified key must not be re-suggested");
+  assert.ok(dedupedKeys.includes("format"));
+  assert.ok(dedupedKeys.includes("timezone"));
+  assert.ok(dedupedKeys.includes("onNull"));
+});
+
+test("completes $switch branches array elements and fields", () => {
+  // Empty branch object inside branches array suggests switchBranch keys: case and then
+  const branchKeys = labels("db.users.aggregate([{ $project: { d: { $switch: { branches: [ { ");
+  assert.ok(branchKeys.includes("case"));
+  assert.ok(branchKeys.includes("then"));
+
+  // After specifying case, used key deduplication leaves then
+  const branchAfterCase = labels("db.users.aggregate([{ $project: { d: { $switch: { branches: [ { case: 1, ");
+  assert.equal(branchAfterCase.includes("case"), false);
+  assert.ok(branchAfterCase.includes("then"));
+
+  // Context mode verification
+  const branchCtx = getMongoCompletionContext("db.users.aggregate([{ $project: { d: { $switch: { branches: [ { ", "db.users.aggregate([{ $project: { d: { $switch: { branches: [ { ".length);
+  assert.equal(branchCtx.mode, "operatorField");
+  assert.equal(branchCtx.operator, "switchBranch");
+
+  // In value position of case:, fieldRef mode is used
+  const caseValCtx = getMongoCompletionContext("db.users.aggregate([{ $project: { d: { $switch: { branches: [ { case: ", "db.users.aggregate([{ $project: { d: { $switch: { branches: [ { case: ".length);
+  assert.equal(caseValCtx.mode, "fieldRef");
+});
+
+test("completes expression operator sub-keys and enums inside $expr in find() and $match", () => {
+  // find() with $expr -> $dateToString keys
+  const findExprDate = labels("db.users.find({ $expr: { $dateToString: { ");
+  assert.ok(findExprDate.includes("date"));
+  assert.ok(findExprDate.includes("format"));
+  assert.ok(findExprDate.includes("timezone"));
+  assert.ok(findExprDate.includes("onNull"));
+
+  // find() with $expr -> $regexMatch options enum
+  const findExprRegexOptions = labels("db.users.find({ $expr: { $regexMatch: { options: ");
+  assert.ok(findExprRegexOptions.includes("i"));
+  assert.ok(findExprRegexOptions.includes("m"));
+
+  // find() with $expr -> $dateToParts iso8601 enum
+  const findExprDatePartsIso = labels("db.users.find({ $expr: { $dateToParts: { iso8601: ");
+  assert.ok(findExprDatePartsIso.includes("true"));
+  assert.ok(findExprDatePartsIso.includes("false"));
+
+  // find() with $expr -> $switch branches
+  const findExprSwitchBranch = labels("db.users.find({ $expr: { $switch: { branches: [ { ");
+  assert.ok(findExprSwitchBranch.includes("case"));
+  assert.ok(findExprSwitchBranch.includes("then"));
+
+  // $match with $expr -> $dateToString keys
+  const matchExprDate = labels("db.users.aggregate([{ $match: { $expr: { $dateToString: { ");
+  assert.ok(matchExprDate.includes("date"));
+  assert.ok(matchExprDate.includes("format"));
+
+  // $match with $expr -> $regexMatch options enum
+  const matchExprRegexOptions = labels("db.users.aggregate([{ $match: { $expr: { $regexMatch: { options: ");
+  assert.ok(matchExprRegexOptions.includes("i"));
+  assert.ok(matchExprRegexOptions.includes("m"));
+});
+
+test("completes expression operator sub-keys and enums in $group", () => {
+  // $group _id compound key with $dateToString
+  const groupIdDate = labels("db.users.aggregate([{ $group: { _id: { day: { $dateToString: { ");
+  assert.ok(groupIdDate.includes("date"));
+  assert.ok(groupIdDate.includes("format"));
+
+  // $group accumulator with expression sub-keys and enums
+  const groupAccumDate = labels("db.users.aggregate([{ $group: { total: { $sum: { $dateToString: { ");
+  assert.ok(groupAccumDate.includes("date"));
+  assert.ok(groupAccumDate.includes("format"));
+
+  const groupAccumRegexOpt = labels("db.users.aggregate([{ $group: { total: { $sum: { $regexMatch: { options: ");
+  assert.ok(groupAccumRegexOpt.includes("i"));
+  assert.ok(groupAccumRegexOpt.includes("m"));
+});