diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
index a8739a7..d301097 100644
--- a/.claude-plugin/marketplace.json
+++ b/.claude-plugin/marketplace.json
@@ -10,7 +10,7 @@
       "name": "genesys-cloud-architect",
       "source": "./",
       "description": "Create, test, and debug Genesys Cloud Architect flows",
-      "version": "1.0.3"
+      "version": "1.0.4"
     }
   ]
 }
diff --git a/.claude-plugin/plugin.json b/.claude-plugin/plugin.json
index 1364be0..59cbabf 100644
--- a/.claude-plugin/plugin.json
+++ b/.claude-plugin/plugin.json
@@ -1,7 +1,7 @@
 {
   "name": "genesys-cloud-architect",
   "description": "Create, test, and debug Genesys Cloud Architect flows",
-  "version": "1.0.3",
+  "version": "1.0.4",
   "author": {
     "name": "Lucas Woodward",
     "url": "https://makingchatbots.com/"
diff --git a/package.json b/package.json
index 6bc266c..a1002e5 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "genesys-cloud-architect",
-  "version": "1.0.3",
+  "version": "1.0.4",
   "private": true,
   "packageManager": "pnpm@11.1.3+sha512.c85357fe17ca12dd23dd7071822666dfd7e3cb76fe214e3370b5ea2fb34f2a231185509b63e717f3cd0acb38dd3f8d82bcd5e8172400ae678b70ea4fbed0896d",
   "scripts": {
diff --git a/servers/genesys-cloud-architect-mcp.js b/servers/genesys-cloud-architect-mcp.js
index dfed348..027c2d6 100644
--- a/servers/genesys-cloud-architect-mcp.js
+++ b/servers/genesys-cloud-architect-mcp.js
@@ -159,7 +159,7 @@ ${s.warnings.join(`
 `)}`),l({content:[{type:"text",text:f.join(`
 `)+m}]})}else{let f=s?.error??`Deploy runner exited with code ${h}`;l({isError:!0,content:[{type:"text",text:`Deploy failed: ${f}${m}`}]})}})})}});function pI(t){let e=t.toUpperCase();return e.endsWith("FLOW")?e:`${e}FLOW`}function iX(t,e){let i={};for(let n of e){let a=n.type??"UNKNOWN";i[a]||(i[a]=[]),i[a].push({id:n.id??"",name:n.name??"",...n.version?{version:n.version}:{},deleted:n.deleted??!1,updated:n.updated??!1})}return{flow:{id:t.id??"",name:t.name,type:pI(t.type??""),version:t.publishedVersion?.commitVersion??"1"},dependencies:i}}var dI=({architectApi:t})=>({config:{description:"Retrieves all dependencies consumed by a Genesys Cloud Architect flow. Returns the flow metadata and its dependencies grouped by type.",annotations:{title:"Flow Dependencies",readOnlyHint:!0,destructiveHint:!1},inputSchema:{flowId:Qi.string().min(1).describe("The Genesys Cloud Architect flow ID")}},handler:async({flowId:e})=>{try{let i;try{i=await t.getFlow(e)}catch{return{isError:!0,content:[{type:"text",text:`Flow "${e}" not found.`}]}}let n=pI(i.type??""),a=i.publishedVersion?.commitVersion??"1",r=[],s=1;for(;;){let l=await t.getArchitectDependencytrackingConsumedresources(i.id,a,n,{pageSize:100,pageNumber:s});if(l.entities&&r.push(...l.entities),!l.nextUri)break;s++}let o=iX(i,r);return{content:[{type:"text",text:JSON.stringify(o,null,2)}]}}catch(i){return{isError:!0,content:[{type:"text",text:`Failed to retrieve flow dependencies: ${i instanceof Error?i.message:String(i)}`}]}}}});var ry=Qi.object({GENESYS_REGION:Qi.string().min(1),GENESYS_CLIENT_ID:Qi.string().min(1),GENESYS_CLIENT_SECRET:Qi.string().min(1),DEPLOY_SCRIPT_PATH:Qi.string().min(1),PREVENT_LOGIN:Qi.enum(["TRUE","FALSE"]).default("FALSE").transform(t=>t==="TRUE")}).safeParse(process.env);if(!ry.success){let t=ry.error.issues.map(e=>e.path[0]).join(`
  `);console.error(`Missing required environment variables:
- ${t}`),process.exit(1)}var Kt=ry.data,oy=new Cc({name:"genesys-cloud-architect",version:"1.0.3"}),hI=dI({architectApi:new sy.default.ArchitectApi});oy.registerTool("flow_dependencies",hI.config,hI.handler);var gI=cI({region:Kt.GENESYS_REGION,clientId:Kt.GENESYS_CLIENT_ID,clientSecret:Kt.GENESYS_CLIENT_SECRET,deployScriptPath:Kt.DEPLOY_SCRIPT_PATH});oy.registerTool("deploy_flow",gI.config,gI.handler);(async()=>{if(Kt.PREVENT_LOGIN)console.warn("Login for Platform API skipped. Calling tools will result in an auth failure.");else{let e=sy.default.ApiClient.instance;e.setEnvironment(Kt.GENESYS_REGION),await e.loginClientCredentialsGrant(Kt.GENESYS_CLIENT_ID,Kt.GENESYS_CLIENT_SECRET)}let t=new bc;await oy.connect(t)})().catch(t=>{console.error("Failed to start server:",t),process.exit(1)});
+ ${t}`),process.exit(1)}var Kt=ry.data,oy=new Cc({name:"genesys-cloud-architect",version:"1.0.4"}),hI=dI({architectApi:new sy.default.ArchitectApi});oy.registerTool("flow_dependencies",hI.config,hI.handler);var gI=cI({region:Kt.GENESYS_REGION,clientId:Kt.GENESYS_CLIENT_ID,clientSecret:Kt.GENESYS_CLIENT_SECRET,deployScriptPath:Kt.DEPLOY_SCRIPT_PATH});oy.registerTool("deploy_flow",gI.config,gI.handler);(async()=>{if(Kt.PREVENT_LOGIN)console.warn("Login for Platform API skipped. Calling tools will result in an auth failure.");else{let e=sy.default.ApiClient.instance;e.setEnvironment(Kt.GENESYS_REGION),await e.loginClientCredentialsGrant(Kt.GENESYS_CLIENT_ID,Kt.GENESYS_CLIENT_SECRET)}let t=new bc;await oy.connect(t)})().catch(t=>{console.error("Failed to start server:",t),process.exit(1)});
 /*! Bundled license information:
 
 mime-db/index.js:
diff --git a/skills/write-flow/SKILL.md b/skills/write-flow/SKILL.md
index 59daf0a..5e0dc3d 100644
--- a/skills/write-flow/SKILL.md
+++ b/skills/write-flow/SKILL.md
@@ -53,7 +53,8 @@ Before writing any flow code, read these reference files from this skill:
 1. **Always read**: `references/sdk-patterns.md` — core SDK patterns and the `buildFlow` contract
 2. **Always read**: `references/gotchas.md` — SDK quirks that cause silent failures
 3. **Always read**: `references/action-reference.md` — available action types
-4. **Read the matching example** from `references/examples/`:
+4. **Read when the flow uses expressions**: `references/expression-reference.md` — expression language syntax, functions, operators, data types, and common patterns. Read this whenever the flow involves conditional logic, dynamic text, variable manipulation, date/time calculations, or any `setExpression()` / expression property usage.
+5. **Read the matching example** from `references/examples/`:
    - `inbound-call.md` — IVR with menus and queue transfers
    - `inbound-chat.md` — chat greeting and queue transfer
    - `inbound-email.md` — auto-reply and queue transfer
diff --git a/skills/write-flow/references/expression-reference.md b/skills/write-flow/references/expression-reference.md
new file mode 100644
index 0000000..2de5072
--- /dev/null
+++ b/skills/write-flow/references/expression-reference.md
@@ -0,0 +1,230 @@
+# Architect Expression Language
+
+Expressions are string values passed to SDK methods like `setExpression()`, `variableValue`, `numberExpression`, etc. They use Genesys Cloud's own expression syntax — not TypeScript.
+
+## Syntax Rules
+
+- **String literals**: double quotes inside the expression — `'"Hello"'` in TypeScript
+- **Escape sequences**: `\"` `\\` `\t` `\n` `\r`
+- **Decimal separator**: always `.` (culture-invariant)
+- **Property access**: dot notation — `Flow.myJson.userName`
+- **Collection access**: brackets — `Task.Queues[Task.Index]`
+- **NOT_SET**: special "undefined" value, distinct from `""`. Check with `IsSet()` or `IsNotSetOrEmpty()`
+
+## Operators (highest → lowest precedence)
+
+| Precedence | Operators | Notes |
+|---|---|---|
+| 1 | `[]` `.` | Collection/property access |
+| 2 | `-` `!` `~` | Unary minus, logical NOT, bitwise NOT |
+| 3 | `^` | Exponentiation (`2^3 = 8`) |
+| 4 | `*` `/` `%` | Multiply, divide, modulus |
+| 5 | `+` `-` | Add, subtract, string concat |
+| 6 | `<` `<=` `>` `>=` | Comparison |
+| 7 | `==` `!=` | Equality |
+| 8 | `&` | Bitwise AND |
+| 9 | `\|` | Bitwise OR |
+| 10 | `and` | Logical AND |
+| 11 | `or` | Logical OR |
+
+Parentheses `()` override precedence.
+
+## Data Types
+
+### Scalar types
+
+| Type | Range / Notes |
+|---|---|
+| Boolean | `true` / `false` |
+| Integer | -999,999,999,999,999 to 999,999,999,999,999 |
+| Decimal | Up to 40 digits precision |
+| String | Double-quoted text |
+| DateTime | Jan 1 1800 – Dec 31 2200, UTC only |
+| Date | Date only (no time) |
+| Time | Time only (no date) |
+| Duration | Milliseconds (-999T to 999T) |
+| Currency | Decimal amount + ISO 4217 code (`MakeCurrency(5.25, "USD")`) |
+| Phone Number | Has `.dialingCode` property |
+| JSON | Objects, arrays, strings, numbers, booleans, null |
+
+### Network types (org-specific, cannot be created from strings)
+Queue, User, Group, ACD Skill, Language Skill, Schedule, Schedule Group, Emergency Group, Wrapup Code
+
+### Collections
+Most types have collection variants (String Collection, Integer Collection, Queue Collection, etc.). Access items with `GetAt(collection, index)` (0-based).
+
+### Special values
+- `NOT_SET` — undefined, checked with `IsSet()` / `IsNotSetOrEmpty()`
+- `System.MinInt` / `System.MaxInt` — integer boundaries
+- `System.MinDateTime` / `System.MaxDateTime` — datetime boundaries
+
+### Implicit casting
+Architect auto-converts between compatible types. Assigning `3+4` (Integer) to a String variable wraps it as `ToString(3+4)`.
+
+## Variable Scoping
+
+| Prefix | Scope |
+|---|---|
+| `Flow.` | Entire flow |
+| `Task.` | Current task only |
+| `State.` | Current state only |
+| `Call.` | Built-in, inbound/outbound calls (read-only) |
+| `Email.` | Built-in, email flows (read-only) |
+| `Message.` | Built-in, messaging flows (read-only) |
+| `Chat.` | Built-in, chat flows (read-only) |
+| `Session.` | Built-in, bot/survey flows (read-only) |
+| `System.` | System constants |
+
+### Common built-in variables
+
+| Variable | Type | Description |
+|---|---|---|
+| `Call.Ani` | String | Caller's phone number |
+| `Call.CalledAddress` | String | Dialed number |
+| `Call.ConversationID` | String | Conversation ID |
+| `Call.Language` | String | IETF language tag |
+| `Call.CurrentQueue` | Queue | Current queue |
+| `Flow.IsTest` | Boolean | Debug mode flag |
+| `Flow.StartDateTimeUtc` | DateTime | When the flow started |
+
+## Functions
+
+### String
+
+| Function | Description |
+|---|---|
+| `Append(s1, s2, ...)` | Concatenate (preferred over `+`, handles NOT_SET) |
+| `Substring(str, start, length)` | Extract substring |
+| `IndexOf(str, search)` | Find position (0-based, -1 if not found) |
+| `Contains(str, search)` | Check if substring exists → Boolean |
+| `Replace(str, find, replaceWith)` | Replace all occurrences |
+| `ToUpper(str)` | Uppercase |
+| `ToLower(str)` | Lowercase |
+| `Trim(str)` | Remove leading/trailing whitespace |
+| `Length(str)` | String length |
+
+### DateTime
+
+| Function | Description |
+|---|---|
+| `GetCurrentDateTimeUtc()` | Current UTC date/time |
+| `MakeDateTime(y, m, d, h, min, s)` | Construct a DateTime |
+| `Year(dt)` / `Month(dt)` / `Hour(dt)` | Extract components |
+| `DayOfWeek(dt)` | Day of week (integer) |
+| `AddHours(dt, n)` | Add/subtract hours |
+| `AddMinutes(dt, n)` | Add/subtract minutes |
+| `AddDays(dt, n)` | Add/subtract days |
+
+### Type Conversion
+
+| Function | Description |
+|---|---|
+| `ToString(value)` | Convert to string (appends "Z" for DateTime) |
+| `ToInt(str)` | Parse string to integer |
+| `ToDecimal(value)` | Convert to decimal |
+| `ToDateTime(str)` | Parse string to DateTime |
+| `ToDuration(value)` | Convert to duration |
+| `ToPhoneNumber(str)` | Convert to PhoneNumber (enables `.dialingCode`) |
+| `ToJson(value)` | Convert singleton to JSON |
+| `JsonParse(str)` | Parse JSON string (strict: double quotes required) |
+| `ToBoolean(value)` | Convert to boolean |
+
+### Logic
+
+| Function | Description |
+|---|---|
+| `If(cond, trueVal, falseVal)` | Conditional (supports nesting) |
+| `IsSet(value)` | True if value is not NOT_SET |
+| `IsNotSetOrEmpty(value)` | True if NOT_SET or empty string |
+
+### Collections
+
+| Function | Description |
+|---|---|
+| `Count(collection)` | Number of items |
+| `GetAt(collection, index)` | Item at index (0-based) |
+| `AddItem(collection, item)` | Append item |
+| `RemoveItem(collection, value)` | Remove by value |
+| `RemoveItemAt(collection, index)` | Remove by index |
+| `Find(collection, value)` | Find items → collection of matches |
+| `FindFirst(collection, value)` | First index (-1 if not found) |
+| `RemoveDups(collection)` | Remove duplicates |
+
+### Audio / TTS (voice flows only)
+
+| Function | Description |
+|---|---|
+| `ToAudioTTS(text)` | Text to speech |
+| `ToAudioBlank(duration)` | Silent pause |
+| `ToAudioNumber(number)` | Read number aloud |
+| `ToAudioPhoneNumber(phone)` | Read phone number aloud |
+
+### Currency
+
+| Function | Description |
+|---|---|
+| `MakeCurrency(amount, code)` | Create currency (`MakeCurrency(5.25, "USD")`) |
+
+## Common Patterns
+
+### Time-of-day greeting
+```
+If(Hour(GetCurrentDateTimeUtc()) < 12, "Good morning", If(Hour(GetCurrentDateTimeUtc()) < 17, "Good afternoon", "Good evening"))
+```
+
+### Safe variable access (NOT_SET guard)
+```
+5 + If(IsSet(Flow.MyInteger), Flow.MyInteger, 0)
+```
+
+### String concatenation (safe)
+```
+Append("Hello ", Flow.CustomerName, "!")
+```
+
+### Check if caller is in a blocked list
+```
+Count(Find(Task.BlockedNumbers, ToPhoneNumber(Call.Ani))) > 0
+```
+
+### Collection lookup with fallback
+```
+If(Task.FoundIndex != -1, GetAt(Task.Queues, Task.FoundIndex), Task.DefaultQueue)
+```
+
+### Business hours check
+```
+Hour(GetCurrentDateTimeUtc()) >= 8 and Hour(GetCurrentDateTimeUtc()) <= 17
+```
+
+### JSON property access
+```
+Flow.MyJson.userName
+```
+
+### Phone number dialing code
+```
+ToPhoneNumber(Call.Ani).dialingCode
+```
+
+## Expression Quoting in the SDK
+
+Expressions are strings inside strings. The outer quotes are TypeScript, the inner quotes are expression syntax:
+
+```typescript
+// String literal in an expression — double quotes inside single quotes
+response.messageBody.setExpression('"Hello!"');
+
+// Variable reference — no inner quotes needed
+setVar.variableValue = "Flow.customerName";
+
+// Function call with string argument
+response.messageBody.setExpression('Append("Hello ", Flow.Name, "!")');
+
+// Conditional with string results
+comm.communicationExpression.setExpression(
+    'If(Hour(GetCurrentDateTimeUtc()) < 12, "Good morning", "Good afternoon")'
+);
+```
+
+Only string literals inside expressions need the inner double quotes. Variable references, function calls returning non-strings, and numeric literals do not.
\ No newline at end of file