diff --git a/.quokka b/.quokka
new file mode 100644
index 0000000..275c1ef
--- /dev/null
+++ b/.quokka
@@ -0,0 +1,5 @@
+{
+  "bun": {
+    "usageMode": "alwaysUse"
+  }
+}
\ No newline at end of file
diff --git a/src/editor/autocomplete.test.ts b/src/editor/autocomplete.test.ts
new file mode 100644
index 0000000..ac1cca6
--- /dev/null
+++ b/src/editor/autocomplete.test.ts
@@ -0,0 +1,169 @@
+import { expect, describe, test } from 'bun:test'
+import { EditorState } from '@codemirror/state'
+import { autocomplete, type CompletionItem } from './autocomplete'
+import { shrimpLanguage } from './plugins/shrimpLanguage'
+
+describe('autocomplete function names', () => {
+  test('collects top-level assignments before cursor, excludes after', () => {
+    const names = getNamesInScope(`
+      x = 5
+      <cursor>
+      y = 10
+    `)
+    expect(names).toEqual(['x'])
+  })
+
+  test('collects matches for identifier', () => {
+    const names = getNamesInScope(`
+      alpha = 5
+      bravo = 10
+      a<cursor>
+    `)
+    expect(names).toEqual(['alpha'])
+  })
+
+  test('function parameters and local assignments are visible inside function', () => {
+    const names = getNamesInScope(`
+      do x y:
+        z = 10
+        <cursor>
+    `)
+    expect(names).toEqual(['x', 'y', 'z'])
+  })
+
+  test('function parameters and locals not visible outside function', () => {
+    const names = getNamesInScope(`
+      do x:
+        y = 1
+      end
+      <cursor>
+    `)
+    expect(names).toEqual([])
+  })
+
+  test('inner functions see outer scope variables', () => {
+    const names = getNamesInScope(`
+      x = 1
+      do:
+        y = 2
+        do:
+          <cursor>
+    `)
+    expect(names).toEqual(['y', 'x'])
+  })
+
+  test('if expressions do not create scope boundaries', () => {
+    const names = getNamesInScope(`
+      if true:
+        x = 5
+      end
+      <cursor>
+    `)
+    expect(names).toEqual(['x'])
+  })
+
+  test('assigned function names are visible in scope', () => {
+    const names = getNamesInScope(`
+      add = do x: x + 1 end
+      <cursor>
+    `)
+    expect(names).toEqual(['add'])
+  })
+
+  test('identifiers are visible in conditional scope', () => {
+    const names = getNamesInScope(`
+      add = if true:
+        x = 1
+        <cursor>
+      end
+    `)
+    expect(names).toEqual(['add', 'x'])
+  })
+
+  test('multiple assignments', () => {
+    const names = getNamesInScope(`
+      alpha = alamo = 4
+      <cursor>
+      end
+    `)
+    expect(names).toEqual(['alpha', 'alamo'])
+  })
+})
+
+describe('autocomplete function arguments', () => {
+  test('shows args for shrimp function', () => {
+    const args = getArgsInScope(`
+        add = do x y: x + y end
+        add <cursor>
+      `)
+    expect(args).toEqual(['x', 'y'])
+  })
+
+  test('does not include args already used', () => {
+    const args = getArgsInScope(`
+        add = do x y: x + y end
+        add 5 <cursor>
+      `)
+    expect(args).toEqual(['y'])
+  })
+
+  test('no args when cursor in function name', () => {
+    const items = getVarsInScope(`
+        add = do x y: x + y end
+        ad<cursor>d
+      `)
+    expect(items.every((i) => i.kind !== 'arg')).toBe(true)
+  })
+
+  test('no args when function not found', () => {
+    const args = getArgsInScope(`
+        unknown <cursor>
+      `)
+    expect(args).toEqual([])
+  })
+})
+
+// Helper functions
+
+const getVarsInScope = (codeWithCursor: string): CompletionItem[] => {
+  const cursorPos = codeWithCursor.indexOf('<cursor>')
+  if (cursorPos === -1) {
+    throw new Error('Test code must contain <cursor> marker')
+  }
+
+  const code = codeWithCursor.replace('<cursor>', '')
+  const view = createMockView(code, cursorPos)
+
+  const items = autocomplete(view)
+  return items
+}
+
+const createMockView = (code: string, cursorPos: number) => {
+  const state = EditorState.create({
+    doc: code,
+    selection: { anchor: cursorPos },
+    extensions: [shrimpLanguage],
+  })
+
+  return { state, dispatch: () => {} } as any
+}
+
+const getNamesInScope = (codeWithCursor: string): string[] => {
+  return getVarsInScope(codeWithCursor).map((v) => v.name)
+}
+
+const getArgsInScope = (codeWithCursor: string): string[] => {
+  const items = getVarsInScope(codeWithCursor)
+
+  for (const item of items) {
+    if (item.kind !== 'arg') {
+      throw new Error(`Expected only arg items, but got kind=${item.kind}`)
+    }
+  }
+
+  return items.map((v) => v.name)
+}
+
+const getArgItems = (codeWithCursor: string): CompletionItem[] => {
+  return getVarsInScope(codeWithCursor).filter((v) => v.kind === 'arg')
+}
diff --git a/src/editor/autocomplete.ts b/src/editor/autocomplete.ts
new file mode 100644
index 0000000..a4d19bc
--- /dev/null
+++ b/src/editor/autocomplete.ts
@@ -0,0 +1,305 @@
+import type { EditorView } from '@codemirror/view'
+import { syntaxTree } from '@codemirror/language'
+import type { SyntaxNode, Tree } from '@lezer/common'
+import * as Terms from '../parser/shrimp.terms'
+import { noseSignals, type CommandDef } from '#editor/noseClient'
+
+export const autocomplete = (view: EditorView): CompletionItem[] => {
+  const fnCallContext = findFunctionCallContext(view)
+
+  if (fnCallContext) {
+    return autocompleteArg(view, fnCallContext)
+  } else {
+    return autocompleteIdentifier(view)
+  }
+}
+
+const autocompleteIdentifier = (view: EditorView): CompletionItem[] => {
+  const cursor = view.state.selection.main.head
+  const tree = syntaxTree(view.state)
+  const node = tree.resolveInner(cursor, -1)
+
+  const textBeforeCursor = view.state.doc.sliceString(node.from, cursor)
+  const wordToComplete = /\W$/.test(textBeforeCursor) ? '' : textBeforeCursor
+  if (wordToComplete !== '' && node.type.id !== Terms.Identifier) return []
+
+  const scope = [...completionItemsInScope(view, tree, cursor), ...noseCompletionItems]
+  scope.push(...noseCompletionItems)
+
+  const matchedItems = scope.filter((scopeItem) => scopeItem.name.startsWith(wordToComplete))
+  return matchedItems
+}
+
+const autocompleteArg = (view: EditorView, context: FunctionCallContext): CompletionItem[] => {
+  const fnNameText = view.state.doc.sliceString(context.fnName.from, context.fnName.to)
+
+  const cursor = view.state.selection.main.head
+  const tree = syntaxTree(view.state)
+  const scope = [...completionItemsInScope(view, tree, cursor), ...noseCompletionItems]
+  const fn = scope.find((item) => item.name === fnNameText)
+
+  if (!fn) {
+    return []
+  }
+
+  // Count how many positional args have already been used
+  const usedPositionalArgs = countPositionalArgs(context.fnCallNode, cursor)
+
+  if (fn.kind === 'shrimp-fn') {
+    // Skip params that have already been filled positionally
+    const remainingParams = fn.params.slice(usedPositionalArgs)
+    return remainingParams.map((paramName) => ({ kind: 'arg', name: paramName }))
+  } else if (fn.kind === 'nose-command') {
+    // Skip params that have already been filled positionally
+    const remainingParams = fn.def.signature.params.slice(usedPositionalArgs)
+    return remainingParams.map((param) => ({
+      kind: 'arg',
+      name: param.name,
+      type: param.type,
+      optional: param.optional,
+      default: param.default,
+    }))
+  }
+
+  return []
+}
+
+const completionItemsInScope = (view: EditorView, tree: Tree, cursor: number): CompletionItem[] => {
+  const items: CompletionItem[] = []
+
+  const containingFunctions = [...findContainingFunctions(tree, cursor), tree.topNode]
+
+  for (const fn of containingFunctions) {
+    const params = collectParams(view, fn)
+    items.push(...params)
+
+    const assignments = collectAssignments(view, fn, cursor)
+    items.push(...assignments)
+  }
+
+  // Remove duplicates by name, keeping first occurrence
+  const seen = new Set<string>()
+  return items.filter((item) => {
+    if (seen.has(item.name)) return false
+    seen.add(item.name)
+    return true
+  })
+}
+
+const findContainingFunctions = (tree: Tree, cursor: number): SyntaxNode[] => {
+  const functions: SyntaxNode[] = []
+
+  tree.topNode.cursor().iterate((node) => {
+    if (node.type.id === Terms.FunctionDef) {
+      const fn = node.node
+      if (isCursorInNode(cursor, fn)) {
+        functions.push(fn)
+      }
+    }
+  })
+
+  return functions
+}
+
+const collectParams = (view: EditorView, fnNode: SyntaxNode): CompletionItem[] => {
+  const params: CompletionItem[] = []
+
+  // Find Params child
+  let child = fnNode.firstChild
+  while (child) {
+    if (child.type.id === Terms.Params) {
+      let param = child.firstChild
+      while (param) {
+        if (param.type.id === Terms.Identifier) {
+          const text = view.state.doc.sliceString(param.from, param.to)
+          params.push({ kind: 'var', name: text })
+        }
+        param = param.nextSibling
+      }
+      break
+    }
+    child = child.nextSibling
+  }
+
+  return params
+}
+
+const collectAssignments = (
+  view: EditorView,
+  scopeNode: SyntaxNode,
+  cursor: number
+): CompletionItem[] => {
+  const assignments: CompletionItem[] = []
+
+  scopeNode.cursor().iterate((node) => {
+    if (node.from >= cursor) return false
+
+    if (node.type.id === Terms.Assign) {
+      const assignNode = node.node
+      let child = assignNode.firstChild
+      if (child?.type.id === Terms.AssignableIdentifier) {
+        const name = view.state.doc.sliceString(child.from, child.to)
+
+        // Check if RHS is a FunctionDef
+        const rhs = child.nextSibling?.nextSibling // Skip the '=' token
+        if (rhs?.type.id === Terms.FunctionDef) {
+          const params = extractParamsFromFunctionDef(view, rhs)
+          assignments.push({ kind: 'shrimp-fn', name, params })
+        } else {
+          assignments.push({ kind: 'var', name })
+        }
+      }
+    }
+
+    // Don't go into nested functions unless it's the current scope
+    if (node.type.id === Terms.FunctionDef && node.node !== scopeNode) {
+      return false
+    }
+  })
+
+  return assignments
+}
+
+const extractParamsFromFunctionDef = (view: EditorView, fnNode: SyntaxNode): string[] => {
+  const params: string[] = []
+  let child = fnNode.firstChild
+  while (child) {
+    if (child.type.id === Terms.Params) {
+      let param = child.firstChild
+      while (param) {
+        if (param.type.id === Terms.Identifier) {
+          const text = view.state.doc.sliceString(param.from, param.to)
+          params.push(text)
+        }
+        param = param.nextSibling
+      }
+      break
+    }
+    child = child.nextSibling
+  }
+  return params
+}
+
+const isCursorInNode = (cursor: number, node: SyntaxNode): boolean => {
+  return cursor >= node.from && cursor <= node.to
+}
+
+// Helper: Find first ancestor matching a condition
+const findAncestor = (
+  node: SyntaxNode | null,
+  predicate: (node: SyntaxNode) => boolean
+): SyntaxNode | null => {
+  let current = node
+  while (current) {
+    if (predicate(current)) return current
+    current = current.parent
+  }
+  return null
+}
+
+const findFunctionCallContext = (view: EditorView) => {
+  const cursor = view.state.selection.main.head
+  const tree = syntaxTree(view.state)
+  const node = tree.resolveInner(cursor, -1)
+
+  // Don't provide arg completion if we're typing an identifier
+  if (node.type.id === Terms.Identifier) return null
+
+  // Only show arg completion after whitespace
+  if (cursor > 0) {
+    const charBefore = view.state.doc.sliceString(cursor - 1, cursor)
+    if (!/\s/.test(charBefore)) return null
+  }
+
+  // Check if we're inside an existing arg (editing it)
+  const inArg = findAncestor(
+    node,
+    (n) => n.type.id === Terms.PositionalArg || n.type.id === Terms.NamedArg
+  )
+  if (inArg) return null
+
+  // Scan back until we find a different node
+  const startNode = node
+  const maxScanBack = 10
+
+  for (let pos = cursor - 1; pos >= Math.max(0, cursor - maxScanBack); pos--) {
+    const nodeAtPos = tree.resolveInner(pos, -1)
+
+    // Found a different node - now walk UP from it
+    if (nodeAtPos !== startNode) {
+      const fnCall = findAncestor(
+        nodeAtPos,
+        (n) => n.type.id === Terms.FunctionCall || n.type.id === Terms.FunctionCallOrIdentifier
+      )
+
+      if (fnCall) {
+        const fnName = fnCall.firstChild
+        if (fnName?.type.id === Terms.Identifier) {
+          return { fnCallNode: fnCall, fnName, currentArgNode: node }
+        }
+      }
+      break // Stop after checking first different node
+    }
+  }
+
+  return null
+}
+
+type FunctionCallContext = {
+  fnCallNode: SyntaxNode
+  fnName: SyntaxNode
+  currentArgNode: SyntaxNode
+}
+
+const countPositionalArgs = (fnCallNode: SyntaxNode, cursor: number): number => {
+  let count = 0
+  let child = fnCallNode.firstChild
+
+  while (child) {
+    // Only count PositionalArg nodes that end before cursor
+    if (child.type.id === Terms.PositionalArg && child.to <= cursor) {
+      count++
+    }
+    child = child.nextSibling
+  }
+
+  return count
+}
+
+type ShrimpFn = {
+  kind: 'shrimp-fn'
+  name: string
+  params: string[]
+}
+
+type NoseCommand = {
+  kind: 'nose-command'
+  name: string
+  def: CommandDef
+}
+
+type Var = {
+  kind: 'var'
+  name: string
+}
+
+type ArgCompletion = {
+  kind: 'arg'
+  name: string
+  type?: string // For NoseCommand
+  optional?: boolean // For NoseCommand
+  default?: any // For NoseCommand
+}
+
+export type CompletionItem = ShrimpFn | NoseCommand | Var | ArgCompletion
+
+// Nose Command Signal
+let noseCompletionItems: CompletionItem[] = []
+noseSignals.connect((data) => {
+  if (data.type !== 'command-defs') return
+  noseCompletionItems = data.data.map((def) => ({
+    kind: 'nose-command',
+    name: def.name,
+    def,
+  }))
+})
diff --git a/src/editor/noseClient.ts b/src/editor/noseClient.ts
index a581ae7..653e3de 100644
--- a/src/editor/noseClient.ts
+++ b/src/editor/noseClient.ts
@@ -25,6 +25,19 @@ type IncomingMessage =
     }
   | { type: 'reef-output'; data: Value }
   | { type: 'error'; data: string }
+  | {
+      type: 'command-defs'
+      data: CommandDef[]
+    }
+
+export type CommandDef = {
+  name: string
+  signature: {
+    params: { default: any; name: string; optional: boolean; rest: boolean; type: string }[]
+    returnType: string
+    type: string
+  }
+}
 
 export const noseSignals = new Signal<IncomingMessage>()
 
diff --git a/src/editor/plugins/debugTags.ts b/src/editor/plugins/debugTags.ts
index d959d64..896410b 100644
--- a/src/editor/plugins/debugTags.ts
+++ b/src/editor/plugins/debugTags.ts
@@ -11,19 +11,29 @@ export const debugTags = ViewPlugin.fromClass(
     }
 
     updateStatusBar(view: EditorView) {
-      const pos = view.state.selection.main.head + 1
+      const pos = view.state.selection.main.head
       const tree = syntaxTree(view.state)
 
       let tags: string[] = []
       let node = tree.resolveInner(pos, -1)
 
+      let nodes = []
+      let lastNode = null
       while (node) {
+        nodes.push(node)
         tags.push(node.type.name)
         node = node.parent!
         if (!node) break
       }
 
-      const debugText = tags.length ? tags.reverse().slice(1).join(' > ') : 'No nodes'
+      ;(window as any).l = nodes
+
+      tags = tags.length ? tags.reverse().slice(1) : ['∅'] // remove Program and reverse
+      if (tags.length > 5) {
+        tags = ['...', ...tags.slice(-5)]
+      }
+
+      const debugText = tags.join(' > ')
       statusBarSignal.emit({
         side: 'right',
         message: debugText,
diff --git a/src/editor/plugins/keymap.tsx b/src/editor/plugins/keymap.tsx
index 6c77f14..d2fbe38 100644
--- a/src/editor/plugins/keymap.tsx
+++ b/src/editor/plugins/keymap.tsx
@@ -1,3 +1,4 @@
+import { autocomplete } from '#editor/autocomplete'
 import { multilineModeSignal, outputSignal } from '#editor/editor'
 import { printBytecodeOutput, printParserOutput, runCode } from '#editor/runCode'
 import { EditorState } from '@codemirror/state'
@@ -49,10 +50,26 @@ const customKeymap = keymap.of([
     key: 'Tab',
     preventDefault: true,
     run: (view) => {
-      view.dispatch({
-        changes: { from: view.state.selection.main.from, insert: '  ' },
-        selection: { anchor: view.state.selection.main.from + 2 },
-      })
+      // if only whitespace is before the cursor on the line, insert two spaces
+      const line = view.state.doc.lineAt(view.state.selection.main.from)
+      const textBeforeCursor = line.text.slice(0, view.state.selection.main.from - line.from)
+      if (textBeforeCursor.trim() === '') {
+        view.dispatch({
+          changes: { from: view.state.selection.main.from, insert: '  ' },
+          selection: { anchor: view.state.selection.main.from + 2 },
+        })
+      } else {
+        const matchedItems = autocomplete(view)
+        const colors = {
+          'shrimp-fn': 'black',
+          'nose-command': 'green',
+          var: 'gray',
+        }
+        for (const item of matchedItems) {
+          // print out item with different colors using console.log
+          console.log(`%c${item.name}`, `color: ${colors[item.kind]}`)
+        }
+      }
       return true
     },
   },
diff --git a/src/editor/plugins/shrimpSetup.ts b/src/editor/plugins/shrimpSetup.ts
index 9adaea2..711688f 100644
--- a/src/editor/plugins/shrimpSetup.ts
+++ b/src/editor/plugins/shrimpSetup.ts
@@ -10,6 +10,7 @@ import { shrimpLanguage } from './shrimpLanguage'
 import { shrimpErrors } from './errors'
 import { persistencePlugin } from './persistence'
 import { catchErrors } from './catchErrors'
+import { debugTags } from '#editor/plugins/debugTags'
 
 export const shrimpSetup = (lineNumbersCompartment: Compartment) => {
   return [
@@ -31,5 +32,6 @@ export const shrimpSetup = (lineNumbersCompartment: Compartment) => {
     shrimpHighlighting,
     shrimpErrors,
     persistencePlugin,
+    debugTags,
   ]
 }