diff --git a/Main.lean b/Main.lean
index 9481f2b..28b8126 100644
--- a/Main.lean
+++ b/Main.lean
@@ -72,10 +72,10 @@ def execute (command: Command): Subroutine Lean.Json := do
   errorIndex := errorI "index"
   catalog (_: Catalog): Subroutine Lean.Json := do
     let env ← Lean.MonadEnv.getEnv
-    let names := env.constants.fold (init := []) (λ es name info =>
+    let names := env.constants.fold (init := #[]) (λ acc name info =>
       match to_filtered_symbol name info with
-      | .some x => x::es
-      | .none => es)
+      | .some x => acc.push x
+      | .none => acc)
     return Lean.toJson <| ({ symbols := names }: CatalogResult)
   inspect (args: Inspect): Subroutine Lean.Json := do
     let env ← Lean.MonadEnv.getEnv
diff --git a/Pantograph/Commands.lean b/Pantograph/Commands.lean
index 7d0cb8f..b6442c4 100644
--- a/Pantograph/Commands.lean
+++ b/Pantograph/Commands.lean
@@ -28,7 +28,7 @@ structure InteractionError where
 structure Catalog where
   deriving Lean.FromJson
 structure CatalogResult where
-  symbols: List String
+  symbols: Array String
   deriving Lean.ToJson
 
 -- Print the type of a symbol
@@ -72,7 +72,7 @@ structure ProofTactic where
   tactic: String
   deriving Lean.FromJson
 structure ProofTacticResultSuccess where
-  goals: Array String
+  goals: Array Goal
   nextId?: Option Nat -- Next proof state id
   deriving Lean.ToJson
 structure ProofTacticResultFailure where
diff --git a/Pantograph/Meta.lean b/Pantograph/Meta.lean
index 9072195..3426628 100644
--- a/Pantograph/Meta.lean
+++ b/Pantograph/Meta.lean
@@ -1,7 +1,7 @@
 import Lean
 
 import Pantograph.Symbols
-
+import Pantograph.Serial
 
 /-
 The proof state manipulation system
@@ -78,17 +78,12 @@ def execute_tactic (state: Elab.Tactic.SavedState) (goal: MVarId) (tactic: Strin
   | Except.error err => return .error #[err]
   | Except.ok stx    => tacticM stx { elaborator := .anonymous } |>.run' state.tactic
 
-def goals_to_string (goals: List MVarId): M (Array String) := do
-  let goals ← goals.mapM fun g => do pure $ toString (← Meta.ppGoal g)
-  pure goals.toArray
-
-
 /-- Response for executing a tactic -/
 inductive TacticResult where
   -- Invalid id
   | invalid (message: String): TacticResult
   -- Goes to next state
-  | success (nextId?: Option Nat) (goals: Array String)
+  | success (nextId?: Option Nat) (goals: Array Goal)
   -- Fails with messages
   | failure (messages: Array String)
 
@@ -116,6 +111,10 @@ def ProofTree.execute (stateId: Nat) (goalId: Nat) (tactic: String): StateRefT P
             parentGoalId := goalId
           }
           modify fun s => { s with states := s.states.push proofState }
-        return .success (.some nextId) (← goals_to_string nextGoals)
+        let goals ← nextGoals.mapM fun mvarId => do
+          match (← MonadMCtx.getMCtx).findDecl? mvarId with
+          | .some mvarDecl => serialize_goal mvarDecl
+          | .none => throwError mvarId
+        return .success (.some nextId) goals.toArray
 
 end Pantograph
diff --git a/Pantograph/Serial.lean b/Pantograph/Serial.lean
index 8304665..4b1c620 100644
--- a/Pantograph/Serial.lean
+++ b/Pantograph/Serial.lean
@@ -41,4 +41,71 @@ def type_expr_to_bound (expr: Expr): MetaM BoundExpression := do
     return { binders, target := toString (← Meta.ppExpr body) }
 
 
+structure Variable where
+  name: String
+  /-- Does the name contain a dagger -/
+  isInaccessible: Bool      := false
+  type: String
+  value?: Option String     := .none
+  deriving ToJson
+structure Goal where
+  /-- String case id -/
+  caseName?: Option String  := .none
+  /-- Is the goal in conversion mode -/
+  isConversion: Bool        := false
+  /-- target expression type -/
+  target: String
+  /-- Variables -/
+  vars: Array Variable      := #[]
+  deriving ToJson
+
+/-- Adapted from ppGoal -/
+def serialize_goal (mvarDecl: MetavarDecl) : MetaM Goal := do
+  -- Options for printing; See Meta.ppGoal for details
+  let showLetValues  := True
+  let ppAuxDecls     := false
+  let ppImplDetailHyps := false
+  let lctx           := mvarDecl.lctx
+  let lctx           := lctx.sanitizeNames.run' { options := (← getOptions) }
+  Meta.withLCtx lctx mvarDecl.localInstances do
+    let rec ppVars (localDecl : LocalDecl) : MetaM Variable := do
+      match localDecl with
+      | .cdecl _ _ varName type _ _ =>
+        let varName := varName.simpMacroScopes
+        let type ← instantiateMVars type
+        return {
+          name := toString varName,
+          isInaccessible := varName.isInaccessibleUserName,
+          type := toString <| ← Meta.ppExpr type
+        }
+      | .ldecl _ _ varName type val _ _ => do
+        let varName := varName.simpMacroScopes
+        let type ← instantiateMVars type
+        let value? ← if showLetValues then
+          let val ← instantiateMVars val
+          pure $ .some <| toString <| (← Meta.ppExpr val)
+        else
+          pure $ .none
+        return {
+          name := toString varName,
+          isInaccessible := varName.isInaccessibleUserName,
+          type := toString <| ← Meta.ppExpr type
+          value? := value?
+        }
+    let vars ← lctx.foldlM (init := []) fun acc (localDecl : LocalDecl) => do
+       let skip := !ppAuxDecls && localDecl.isAuxDecl || !ppImplDetailHyps && localDecl.isImplementationDetail
+       if skip then
+         return acc
+       else
+         let var ← ppVars localDecl
+         return var::acc
+    return {
+      caseName? := match mvarDecl.userName with
+        | Name.anonymous => .none
+        | name => .some <| toString name,
+      isConversion := "| " == (Meta.getGoalPrefix mvarDecl)
+      target := toString <| (← Meta.ppExpr (← instantiateMVars mvarDecl.type)),
+      vars := vars.reverse.toArray
+    }
+
 end Pantograph
diff --git a/Test/Proofs.lean b/Test/Proofs.lean
index 46c8c6a..52854d4 100644
--- a/Test/Proofs.lean
+++ b/Test/Proofs.lean
@@ -47,6 +47,8 @@ def start_proof (start: Start): M (LSpec.TestSeq × Option ProofTree) := do
           (expr := expr)
         return (testSeq, Option.some state)
 
+deriving instance DecidableEq, Repr for Variable
+deriving instance DecidableEq, Repr for Goal
 deriving instance DecidableEq, Repr for TacticResult
 
 def proof_step (stateId: Nat) (goalId: Nat) (tactic: String)
@@ -88,27 +90,35 @@ def proof_runner (env: Lean.Environment) (start: Start) (steps: List (TestM LSpe
     return LSpec.test "Exception" (s!"internal exception #{← exception.toMessageData.toString}" = "")
   | .ok a            => return a
 
+def build_goal (nameType: List (String × String)) (target: String): Goal :=
+  {
+    target := target,
+    vars := (nameType.map fun x => ({ name := x.fst, type := x.snd }: Variable)).toArray
+  }
 
 example: ∀ (a b: Nat), a + b = b + a := by
   intro n m
   rw [Nat.add_comm]
-def proof_nat_add_comm (env: Lean.Environment): IO LSpec.TestSeq :=
-  let goal1 := "n m : Nat\n⊢ n + m = m + n"
+def proof_nat_add_comm (env: Lean.Environment): IO LSpec.TestSeq := do
+  let goal1: Goal := {
+    target := "n + m = m + n",
+    vars := #[{ name := "n", type := "Nat" }, { name := "m", type := "Nat" }]
+  }
   proof_runner env (.copy "Nat.add_comm") [
     proof_step 0 0 "intro n m"
       (.success (.some 1) #[goal1]),
     proof_step 1 0 "assumption"
-      (.failure #[s!"tactic 'assumption' failed\n{goal1}"]),
+      (.failure #[s!"tactic 'assumption' failed\nn m : Nat\n⊢ n + m = m + n"]),
     proof_step 1 0 "rw [Nat.add_comm]"
       (.success .none #[])
   ]
 def proof_nat_add_comm_manual (env: Lean.Environment): IO LSpec.TestSeq := do
-  let goal1 := "n m : Nat\n⊢ n + m = m + n"
+  let goal1: Goal := build_goal [("n", "Nat"), ("m", "Nat")] "n + m = m + n"
   proof_runner env (.expr "∀ (a b: Nat), a + b = b + a") [
     proof_step 0 0 "intro n m"
       (.success (.some 1) #[goal1]),
     proof_step 1 0 "assumption"
-      (.failure #[s!"tactic 'assumption' failed\n{goal1}"]),
+      (.failure #[s!"tactic 'assumption' failed\nn m : Nat\n⊢ n + m = m + n"]),
     proof_step 1 0 "rw [Nat.add_comm]"
       (.success .none #[])
   ]
@@ -129,11 +139,20 @@ example: ∀ (p q: Prop), p ∨ q → q ∨ p := by
   . apply Or.inl
     assumption
 def proof_or_comm (env: Lean.Environment): IO LSpec.TestSeq := do
+  let branchGoal (caseName name: String): Goal := {
+    caseName? := .some caseName,
+    target := "q ∨ p",
+    vars := #[
+      { name := "p", type := "Prop" },
+      { name := "q", type := "Prop" },
+      { name := "h✝", type := name, isInaccessible := true }
+    ]
+  }
   proof_runner env (.expr "∀ (p q: Prop), p ∨ q → q ∨ p") [
     proof_step 0 0 "intro p q h"
-      (.success (.some 1) #["p q : Prop\nh : p ∨ q\n⊢ q ∨ p"]),
+      (.success (.some 1) #[build_goal [("p", "Prop"), ("q", "Prop"), ("h", "p ∨ q")] "q ∨ p"]),
     proof_step 1 0 "cases h"
-      (.success (.some 2) #[]),
+      (.success (.some 2) #[branchGoal "inl" "p", branchGoal "inr" "q"]),
     proof_inspect #["", "0.0", "1.0"],
     proof_step 2 0 "apply Or.inr"
       (.success (.some 3) #[]),