diff --git a/Pantograph.lean b/Pantograph.lean
index 292efb9..2c334b6 100644
--- a/Pantograph.lean
+++ b/Pantograph.lean
@@ -1,4 +1,5 @@
-import Pantograph.Condensed
+import Pantograph.Delate
+import Pantograph.Elab
 import Pantograph.Environment
 import Pantograph.Frontend
 import Pantograph.Goal
diff --git a/Pantograph/Condensed.lean b/Pantograph/Condensed.lean
deleted file mode 100644
index 125b69c..0000000
--- a/Pantograph/Condensed.lean
+++ /dev/null
@@ -1,95 +0,0 @@
-/- structures for FFI based interface -/
-import Lean
-import Pantograph.Goal
-import Pantograph.Expr
-
-open Lean
-
-namespace Pantograph
-namespace Condensed
-
--- Mirrors Lean's LocalDecl
-structure LocalDecl where
-  -- Default value is for testing
-  fvarId: FVarId := { name := .anonymous }
-  userName: Name
-
-  -- Normalized expression
-  type : Expr
-  value? : Option Expr := .none
-
-structure Goal where
-  mvarId: MVarId := { name := .anonymous }
-  userName: Name := .anonymous
-  context: Array LocalDecl
-  target: Expr
-
-@[export pantograph_goal_is_lhs]
-def isLHS (g: Goal) : Bool := isLHSGoal? g.target |>.isSome
-
--- Functions for creating contexts and states
-@[export pantograph_elab_context]
-def elabContext: Elab.Term.Context := {
-    errToSorry := false
-  }
-
-end Condensed
-
--- Get the list of visible (by default) free variables from a goal
-@[export pantograph_visible_fvars_of_mvar]
-protected def visibleFVarsOfMVar (mctx: MetavarContext) (mvarId: MVarId): Option (Array FVarId) := do
-  let mvarDecl ← mctx.findDecl? mvarId
-  let lctx := mvarDecl.lctx
-  return lctx.decls.foldl (init := #[]) fun r decl? => match decl? with
-    | some decl => if decl.isAuxDecl ∨ decl.isImplementationDetail then r else r.push decl.fvarId
-    | none      => r
-
-@[export pantograph_to_condensed_goal_m]
-def toCondensedGoal (mvarId: MVarId): MetaM Condensed.Goal := do
-  let ppAuxDecls     := Meta.pp.auxDecls.get (← getOptions)
-  let ppImplDetailHyps := Meta.pp.implementationDetailHyps.get (← getOptions)
-  let mvarDecl ← mvarId.getDecl
-  let lctx     := mvarDecl.lctx
-  let lctx     := lctx.sanitizeNames.run' { options := (← getOptions) }
-  Meta.withLCtx lctx mvarDecl.localInstances do
-    let ppVar (localDecl : LocalDecl) : MetaM Condensed.LocalDecl := do
-      match localDecl with
-      | .cdecl _ fvarId userName type _ _ =>
-        let type ← instantiate type
-        return { fvarId, userName, type }
-      | .ldecl _ fvarId userName type value _ _ => do
-        let userName := userName.simpMacroScopes
-        let type ← instantiate type
-        let value ← instantiate value
-        return { fvarId, userName, type, value? := .some 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 ← ppVar localDecl
-        return var::acc
-    return {
-        mvarId,
-        userName := mvarDecl.userName,
-        context := vars.reverse.toArray,
-        target := ← instantiate mvarDecl.type
-    }
-  where
-  instantiate := instantiateAll
-
-@[export pantograph_goal_state_to_condensed_m]
-protected def GoalState.toCondensed (state: GoalState):
-    CoreM (Array Condensed.Goal):= do
-  let metaM := do
-    let goals := state.goals.toArray
-    goals.mapM fun goal => do
-      match state.mctx.findDecl? goal with
-      | .some _ =>
-        let serializedGoal ← toCondensedGoal goal
-        pure serializedGoal
-      | .none => throwError s!"Metavariable does not exist in context {goal.name}"
-  metaM.run' (s := state.savedState.term.meta.meta)
-
-end Pantograph
diff --git a/Pantograph/Delate.lean b/Pantograph/Delate.lean
new file mode 100644
index 0000000..be17729
--- /dev/null
+++ b/Pantograph/Delate.lean
@@ -0,0 +1,562 @@
+/-
+This file handles "Delation": The conversion of Kernel view into Search view.
+-/
+import Lean
+import Std.Data.HashMap
+import Pantograph.Goal
+import Pantograph.Protocol
+
+open Lean
+
+-- Symbol processing functions --
+
+namespace Pantograph
+
+structure ProjectionApplication where
+  projector: Name
+  numParams: Nat
+  inner: Expr
+
+@[export pantograph_expr_proj_to_app]
+def exprProjToApp (env: Environment) (e: Expr): ProjectionApplication :=
+  let (typeName, idx, inner) := match e with
+    | .proj typeName idx inner => (typeName, idx, inner)
+    | _ => panic! "Argument must be proj"
+  let ctor := getStructureCtor env typeName
+  let fieldName := getStructureFields env typeName |>.get! idx
+  let projector := getProjFnForField? env typeName fieldName |>.get!
+  {
+    projector,
+    numParams := ctor.numParams,
+    inner,
+  }
+
+def _root_.Lean.Name.isAuxLemma (n : Lean.Name) : Bool := n matches .num (.str _ "_auxLemma") _
+
+/-- Unfold all lemmas created by `Lean.Meta.mkAuxLemma`. These end in `_auxLemma.nn` where `nn` is a number. -/
+@[export pantograph_unfold_aux_lemmas]
+def unfoldAuxLemmas (e : Expr) : CoreM Expr := do
+  Lean.Meta.deltaExpand e Lean.Name.isAuxLemma
+
+/--
+Force the instantiation of delayed metavariables even if they cannot be fully
+instantiated. This is used during resumption to provide diagnostic data about
+the current goal.
+
+Since Lean 4 does not have an `Expr` constructor corresponding to delayed
+metavariables, any delayed metavariables must be recursively handled by this
+function to ensure that nested delayed metavariables can be properly processed.
+The caveat is this recursive call will lead to infinite recursion if a loop
+between metavariable assignment exists.
+
+This function ensures any metavariable in the result is either
+1. Delayed assigned with its pending mvar not assigned in any form
+2. Not assigned (delay or not)
+ -/
+partial def instantiateDelayedMVars (eOrig: Expr) : MetaM Expr := do
+  --let padding := String.join $ List.replicate level "│ "
+  --IO.println s!"{padding}Starting {toString eOrig}"
+  let mut result ← Meta.transform (← instantiateMVars eOrig)
+    (pre := fun e => e.withApp fun f args => do
+      let .mvar mvarId := f | return .continue
+      --IO.println s!"{padding}├V {e}"
+      let mvarDecl ← mvarId.getDecl
+
+      -- This is critical to maintaining the interdependency of metavariables.
+      -- Without setting `.syntheticOpaque`, Lean's metavariable elimination
+      -- system will not make the necessary delayed assigned mvars in case of
+      -- nested mvars.
+      mvarId.setKind .syntheticOpaque
+
+      mvarId.withContext do
+        let lctx ← MonadLCtx.getLCtx
+        if mvarDecl.lctx.any (λ decl => !lctx.contains decl.fvarId) then
+          let violations := mvarDecl.lctx.decls.foldl (λ acc decl? => match decl? with
+            | .some decl => if lctx.contains decl.fvarId then acc else acc ++ [decl.fvarId.name]
+            | .none => acc) []
+          panic! s!"In the context of {mvarId.name}, there are local context variable violations: {violations}"
+
+        if let .some assign ← getExprMVarAssignment? mvarId then
+          --IO.println s!"{padding}├A ?{mvarId.name}"
+          assert! !(← mvarId.isDelayedAssigned)
+          return .visit (mkAppN assign args)
+        else if let some { fvars, mvarIdPending } ← getDelayedMVarAssignment? mvarId then
+          --let substTableStr := String.intercalate ", " $ Array.zipWith fvars args (λ fvar assign => s!"{fvar.fvarId!.name} := {assign}") |>.toList
+          --IO.println s!"{padding}├MD ?{mvarId.name} := ?{mvarIdPending.name} [{substTableStr}]"
+
+          if args.size < fvars.size then
+            throwError "Not enough arguments to instantiate a delay assigned mvar. This is due to bad implementations of a tactic: {args.size} < {fvars.size}. Expr: {toString e}; Origin: {toString eOrig}"
+          --if !args.isEmpty then
+            --IO.println s!"{padding}├── Arguments Begin"
+          let args ← args.mapM self
+          --if !args.isEmpty then
+            --IO.println s!"{padding}├── Arguments End"
+          if !(← mvarIdPending.isAssignedOrDelayedAssigned) then
+            --IO.println s!"{padding}├T1"
+            let result := mkAppN f args
+            return .done result
+
+          let pending ← mvarIdPending.withContext do
+            let inner ← instantiateDelayedMVars (.mvar mvarIdPending) --(level := level + 1)
+            --IO.println s!"{padding}├Pre: {inner}"
+            pure <| (← inner.abstractM fvars).instantiateRev args
+
+          -- Tail arguments
+          let result := mkAppRange pending fvars.size args.size args
+          --IO.println s!"{padding}├MD {result}"
+          return .done result
+        else
+          assert! !(← mvarId.isAssigned)
+          assert! !(← mvarId.isDelayedAssigned)
+          --if !args.isEmpty then
+          --  IO.println s!"{padding}├── Arguments Begin"
+          let args ← args.mapM self
+          --if !args.isEmpty then
+          --  IO.println s!"{padding}├── Arguments End"
+
+          --IO.println s!"{padding}├M ?{mvarId.name}"
+          return .done (mkAppN f args))
+  --IO.println s!"{padding}└Result {result}"
+  return result
+  where
+  self e := instantiateDelayedMVars e --(level := level + 1)
+
+/--
+Convert an expression to an equiavlent form with
+1. No nested delayed assigned mvars
+2. No aux lemmas
+3. No assigned mvars
+ -/
+@[export pantograph_instantiate_all_m]
+def instantiateAll (e: Expr): MetaM Expr := do
+  let e ← instantiateDelayedMVars e
+  let e ← unfoldAuxLemmas e
+  return e
+
+structure DelayedMVarInvocation where
+  mvarIdPending: MVarId
+  args: Array (FVarId × (Option Expr))
+  -- Extra arguments applied to the result of this substitution
+  tail: Array Expr
+
+-- The pending mvar of any delayed assigned mvar must not be assigned in any way.
+@[export pantograph_to_delayed_mvar_invocation_m]
+def toDelayedMVarInvocation (e: Expr): MetaM (Option DelayedMVarInvocation) := do
+  let .mvar mvarId := e.getAppFn | return .none
+  let .some decl ← getDelayedMVarAssignment? mvarId | return .none
+  let mvarIdPending := decl.mvarIdPending
+  let mvarDecl ← mvarIdPending.getDecl
+  -- Print the function application e. See Lean's `withOverApp`
+  let args := e.getAppArgs
+
+  assert! args.size ≥ decl.fvars.size
+  assert! !(← mvarIdPending.isAssigned)
+  assert! !(← mvarIdPending.isDelayedAssigned)
+  let fvarArgMap: Std.HashMap FVarId Expr := Std.HashMap.ofList $ (decl.fvars.map (·.fvarId!) |>.zip args).toList
+  let subst ← mvarDecl.lctx.foldlM (init := []) λ acc localDecl => do
+    let fvarId := localDecl.fvarId
+    let a := fvarArgMap[fvarId]?
+    return acc ++ [(fvarId, a)]
+
+  assert! decl.fvars.all (λ fvar => mvarDecl.lctx.findFVar? fvar |>.isSome)
+
+  return .some {
+    mvarIdPending,
+    args := subst.toArray,
+    tail := args.toList.drop decl.fvars.size |>.toArray,
+  }
+
+-- Condensed representation
+
+namespace Condensed
+
+-- Mirrors Lean's LocalDecl
+structure LocalDecl where
+  -- Default value is for testing
+  fvarId: FVarId := { name := .anonymous }
+  userName: Name
+
+  -- Normalized expression
+  type : Expr
+  value? : Option Expr := .none
+
+structure Goal where
+  mvarId: MVarId := { name := .anonymous }
+  userName: Name := .anonymous
+  context: Array LocalDecl
+  target: Expr
+
+@[export pantograph_goal_is_lhs]
+def isLHS (g: Goal) : Bool := isLHSGoal? g.target |>.isSome
+
+end Condensed
+
+-- Get the list of visible (by default) free variables from a goal
+@[export pantograph_visible_fvars_of_mvar]
+protected def visibleFVarsOfMVar (mctx: MetavarContext) (mvarId: MVarId): Option (Array FVarId) := do
+  let mvarDecl ← mctx.findDecl? mvarId
+  let lctx := mvarDecl.lctx
+  return lctx.decls.foldl (init := #[]) fun r decl? => match decl? with
+    | some decl => if decl.isAuxDecl ∨ decl.isImplementationDetail then r else r.push decl.fvarId
+    | none      => r
+
+@[export pantograph_to_condensed_goal_m]
+def toCondensedGoal (mvarId: MVarId): MetaM Condensed.Goal := do
+  let ppAuxDecls     := Meta.pp.auxDecls.get (← getOptions)
+  let ppImplDetailHyps := Meta.pp.implementationDetailHyps.get (← getOptions)
+  let mvarDecl ← mvarId.getDecl
+  let lctx     := mvarDecl.lctx
+  let lctx     := lctx.sanitizeNames.run' { options := (← getOptions) }
+  Meta.withLCtx lctx mvarDecl.localInstances do
+    let ppVar (localDecl : LocalDecl) : MetaM Condensed.LocalDecl := do
+      match localDecl with
+      | .cdecl _ fvarId userName type _ _ =>
+        let type ← instantiate type
+        return { fvarId, userName, type }
+      | .ldecl _ fvarId userName type value _ _ => do
+        let userName := userName.simpMacroScopes
+        let type ← instantiate type
+        let value ← instantiate value
+        return { fvarId, userName, type, value? := .some 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 ← ppVar localDecl
+        return var::acc
+    return {
+        mvarId,
+        userName := mvarDecl.userName,
+        context := vars.reverse.toArray,
+        target := ← instantiate mvarDecl.type
+    }
+  where
+  instantiate := instantiateAll
+
+@[export pantograph_goal_state_to_condensed_m]
+protected def GoalState.toCondensed (state: GoalState):
+    CoreM (Array Condensed.Goal):= do
+  let metaM := do
+    let goals := state.goals.toArray
+    goals.mapM fun goal => do
+      match state.mctx.findDecl? goal with
+      | .some _ =>
+        let serializedGoal ← toCondensedGoal goal
+        pure serializedGoal
+      | .none => throwError s!"Metavariable does not exist in context {goal.name}"
+  metaM.run' (s := state.savedState.term.meta.meta)
+
+def typeExprToBound (expr: Expr): MetaM Protocol.BoundExpression := do
+  Meta.forallTelescope expr fun arr body => do
+    let binders ← arr.mapM fun fvar => do
+      return (toString (← fvar.fvarId!.getUserName), toString (← Meta.ppExpr (← fvar.fvarId!.getType)))
+    return { binders, target := toString (← Meta.ppExpr body) }
+
+def serializeName (name: Name) (sanitize: Bool := true): String :=
+  let internal := name.isInaccessibleUserName || name.hasMacroScopes
+  if sanitize && internal then "_"
+  else toString name |> addQuotes
+  where
+  addQuotes (n: String) :=
+    let quote := "\""
+    if n.contains Lean.idBeginEscape then s!"{quote}{n}{quote}" else n
+
+/-- serialize a sort level. Expression is optimized to be compact e.g. `(+ u 2)` -/
+partial def serializeSortLevel (level: Level) (sanitize: Bool): String :=
+  let k := level.getOffset
+  let u := level.getLevelOffset
+  let u_str := match u with
+    | .zero => "0"
+    | .succ _ => panic! "getLevelOffset should not return .succ"
+    | .max v w =>
+      let v := serializeSortLevel v sanitize
+      let w := serializeSortLevel w sanitize
+      s!"(:max {v} {w})"
+    | .imax v w =>
+      let v := serializeSortLevel v sanitize
+      let w := serializeSortLevel w sanitize
+      s!"(:imax {v} {w})"
+    | .param name =>
+      let name := serializeName name sanitize
+      s!"{name}"
+    | .mvar id =>
+      let name := serializeName id.name sanitize
+      s!"(:mv {name})"
+  match k, u with
+  | 0, _ => u_str
+  | _, .zero => s!"{k}"
+  | _, _ => s!"(+ {u_str} {k})"
+
+
+/--
+ Completely serializes an expression tree. Json not used due to compactness
+
+A `_` symbol in the AST indicates automatic deductions not present in the original expression.
+-/
+partial def serializeExpressionSexp (expr: Expr) (sanitize: Bool := true): MetaM String := do
+  self expr
+  where
+  delayedMVarToSexp (e: Expr): MetaM (Option String) := do
+    let .some invocation ← toDelayedMVarInvocation e | return .none
+    let callee ← self $ .mvar invocation.mvarIdPending
+    let sites ← invocation.args.mapM (λ (fvarId, arg) => do
+        let arg := match arg with
+          | .some arg => arg
+          | .none => .fvar fvarId
+        self arg
+      )
+    let tailArgs ← invocation.tail.mapM self
+
+    let sites := " ".intercalate sites.toList
+    let result := if tailArgs.isEmpty then
+        s!"(:subst {callee} {sites})"
+      else
+        let tailArgs := " ".intercalate tailArgs.toList
+        s!"((:subst {callee} {sites}) {tailArgs})"
+    return .some result
+
+  self (e: Expr): MetaM String := do
+    if let .some result ← delayedMVarToSexp e then
+      return result
+    match e with
+    | .bvar deBruijnIndex =>
+      -- This is very common so the index alone is shown. Literals are handled below.
+      -- The raw de Bruijn index should never appear in an unbound setting. In
+      -- Lean these are handled using a `#` prefix.
+      pure s!"{deBruijnIndex}"
+    | .fvar fvarId =>
+      let name := ofName fvarId.name
+      pure s!"(:fv {name})"
+    | .mvar mvarId => do
+        let pref := if ← mvarId.isDelayedAssigned then "mvd" else "mv"
+        let name := ofName mvarId.name
+        pure s!"(:{pref} {name})"
+    | .sort level =>
+      let level := serializeSortLevel level sanitize
+      pure s!"(:sort {level})"
+    | .const declName _ =>
+      -- The universe level of the const expression is elided since it should be
+      -- inferrable from surrounding expression
+      pure s!"(:c {declName})"
+    | .app _ _ => do
+      let fn' ← self e.getAppFn
+      let args := (← e.getAppArgs.mapM self) |>.toList
+      let args := " ".intercalate args
+      pure s!"({fn'} {args})"
+    | .lam binderName binderType body binderInfo => do
+      let binderName' := ofName binderName
+      let binderType' ← self binderType
+      let body' ← self body
+      let binderInfo' := binderInfoSexp binderInfo
+      pure s!"(:lambda {binderName'} {binderType'} {body'}{binderInfo'})"
+    | .forallE binderName binderType body binderInfo => do
+      let binderName' := ofName binderName
+      let binderType' ← self binderType
+      let body' ← self body
+      let binderInfo' := binderInfoSexp binderInfo
+      pure s!"(:forall {binderName'} {binderType'} {body'}{binderInfo'})"
+    | .letE name type value body _ => do
+      -- Dependent boolean flag diacarded
+      let name' := serializeName name
+      let type' ← self type
+      let value' ← self value
+      let body' ← self body
+      pure s!"(:let {name'} {type'} {value'} {body'})"
+    | .lit v =>
+      -- To not burden the downstream parser who needs to handle this, the literal
+      -- is wrapped in a :lit sexp.
+      let v' := match v with
+        | .natVal val => toString val
+        | .strVal val => s!"\"{val}\""
+      pure s!"(:lit {v'})"
+    | .mdata _ inner =>
+      -- NOTE: Equivalent to expr itself, but mdata influences the prettyprinter
+      -- It may become necessary to incorporate the metadata.
+      self inner
+    | .proj _ _ _ => do
+      let env ← getEnv
+      let projApp := exprProjToApp env e
+      let autos := String.intercalate " " (List.replicate projApp.numParams "_")
+      let inner ← self projApp.inner
+      pure s!"((:c {projApp.projector}) {autos} {inner})"
+  -- Elides all unhygenic names
+  binderInfoSexp : Lean.BinderInfo → String
+    | .default => ""
+    | .implicit => " :implicit"
+    | .strictImplicit => " :strictImplicit"
+    | .instImplicit => " :instImplicit"
+  ofName (name: Name) := serializeName name sanitize
+
+def serializeExpression (options: @&Protocol.Options) (e: Expr): MetaM Protocol.Expression := do
+  let pp?: Option String ← match options.printExprPretty with
+    | true => pure $ .some $ toString $ ← Meta.ppExpr e
+    | false => pure $ .none
+  let sexp?: Option String ← match options.printExprAST with
+    | true => pure $ .some $ ← serializeExpressionSexp e
+    | false => pure $ .none
+  let dependentMVars? ← match options.printDependentMVars with
+    | true => pure $ .some $ (← Meta.getMVars e).map (λ mvarId => mvarId.name.toString)
+    | false => pure $ .none
+  return {
+    pp?,
+    sexp?
+    dependentMVars?,
+  }
+
+
+/-- Adapted from ppGoal -/
+def serializeGoal (options: @&Protocol.Options) (goal: MVarId) (mvarDecl: MetavarDecl) (parentDecl?: Option MetavarDecl := .none)
+      : MetaM Protocol.Goal := do
+  -- Options for printing; See Meta.ppGoal for details
+  let showLetValues  := true
+  let ppAuxDecls     := options.printAuxDecls
+  let ppImplDetailHyps := options.printImplementationDetailHyps
+  let lctx           := mvarDecl.lctx
+  let lctx           := lctx.sanitizeNames.run' { options := (← getOptions) }
+  Meta.withLCtx lctx mvarDecl.localInstances do
+    let ppVarNameOnly (localDecl: LocalDecl): MetaM Protocol.Variable := do
+      match localDecl with
+      | .cdecl _ fvarId userName _ _ _ =>
+        return {
+          name := ofName fvarId.name,
+          userName:= ofName userName.simpMacroScopes,
+          isInaccessible := userName.isInaccessibleUserName
+        }
+      | .ldecl _ fvarId userName _ _ _ _ => do
+        return {
+          name := ofName fvarId.name,
+          userName := toString userName.simpMacroScopes,
+          isInaccessible := userName.isInaccessibleUserName
+        }
+    let ppVar (localDecl : LocalDecl) : MetaM Protocol.Variable := do
+      match localDecl with
+      | .cdecl _ fvarId userName type _ _ =>
+        let userName := userName.simpMacroScopes
+        let type ← instantiate type
+        return {
+          name := ofName fvarId.name,
+          userName:= ofName userName,
+          isInaccessible := userName.isInaccessibleUserName
+          type? := .some (← serializeExpression options type)
+        }
+      | .ldecl _ fvarId userName type val _ _ => do
+        let userName := userName.simpMacroScopes
+        let type ← instantiate type
+        let value? ← if showLetValues then
+          let val ← instantiate val
+          pure $ .some (← serializeExpression options val)
+        else
+          pure $ .none
+        return {
+          name := ofName fvarId.name,
+          userName:= ofName userName,
+          isInaccessible := userName.isInaccessibleUserName
+          type? := .some (← serializeExpression options 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 nameOnly := options.noRepeat && (parentDecl?.map
+          (λ decl => decl.lctx.find? localDecl.fvarId |>.isSome) |>.getD false)
+        let var ← match nameOnly with
+          | true => ppVarNameOnly localDecl
+          | false => ppVar localDecl
+        return var::acc
+    return {
+      name := ofName goal.name,
+      userName? := if mvarDecl.userName == .anonymous then .none else .some (ofName mvarDecl.userName),
+      isConversion := isLHSGoal? mvarDecl.type |>.isSome,
+      target := (← serializeExpression options (← instantiate mvarDecl.type)),
+      vars := vars.reverse.toArray
+    }
+  where
+  instantiate := instantiateAll
+  ofName (n: Name) := serializeName n (sanitize := false)
+
+protected def GoalState.serializeGoals
+      (state: GoalState)
+      (parent: Option GoalState := .none)
+      (options: @&Protocol.Options := {}):
+    MetaM (Array Protocol.Goal):= do
+  state.restoreMetaM
+  let goals := state.goals.toArray
+  let parentDecl? := parent.bind (λ parentState => parentState.mctx.findDecl? state.parentMVar?.get!)
+  goals.mapM fun goal => do
+    match state.mctx.findDecl? goal with
+    | .some mvarDecl =>
+      let serializedGoal ← serializeGoal options goal mvarDecl (parentDecl? := parentDecl?)
+      pure serializedGoal
+    | .none => throwError s!"Metavariable does not exist in context {goal.name}"
+
+/-- Print the metavariables in a readable format -/
+@[export pantograph_goal_state_diag_m]
+protected def GoalState.diag (goalState: GoalState) (parent?: Option GoalState := .none) (options: Protocol.GoalDiag := {}): CoreM String := do
+  let metaM: MetaM String := do
+    goalState.restoreMetaM
+    let savedState := goalState.savedState
+    let goals := savedState.tactic.goals
+    let mctx ← getMCtx
+    let root := goalState.root
+    -- Print the root
+    let result: String ← match mctx.decls.find? root with
+      | .some decl => printMVar ">" root decl
+      | .none => pure s!">{root.name}: ??"
+    let resultGoals ← goals.filter (· != root) |>.mapM (fun mvarId =>
+      match mctx.decls.find? mvarId with
+      | .some decl => printMVar "⊢" mvarId decl
+      | .none => pure s!"⊢{mvarId.name}: ??"
+    )
+    let goals := goals.toSSet
+    let resultOthers ← mctx.decls.toList.filter (λ (mvarId, _) =>
+        !(goals.contains mvarId || mvarId == root) && options.printAll)
+        |>.mapM (fun (mvarId, decl) => do
+          let pref := if parentHasMVar mvarId then " " else "~"
+          printMVar pref mvarId decl
+        )
+    pure $ result ++ "\n" ++ (resultGoals.map (· ++ "\n") |> String.join) ++ (resultOthers.map (· ++ "\n") |> String.join)
+  metaM.run' {}
+  where
+    printMVar (pref: String) (mvarId: MVarId) (decl: MetavarDecl): MetaM String := mvarId.withContext do
+      let resultFVars: List String ←
+        if options.printContext then
+          decl.lctx.fvarIdToDecl.toList.mapM (λ (fvarId, decl) =>
+            do pure $ (← printFVar fvarId decl) ++ "\n")
+        else
+          pure []
+      let type ← if options.instantiate
+        then instantiateAll decl.type
+        else pure $ decl.type
+      let type_sexp ← if options.printSexp then
+          let sexp ← serializeExpressionSexp type (sanitize := false)
+          pure <| " " ++ sexp
+        else
+          pure ""
+      let resultMain: String := s!"{pref}{mvarId.name}{userNameToString decl.userName}: {← Meta.ppExpr decl.type}{type_sexp}"
+      let resultValue: String ←
+        if options.printValue then
+          if let .some value ← getExprMVarAssignment? mvarId then
+            let value ← if options.instantiate
+              then instantiateAll value
+              else pure $ value
+            pure s!"\n := {← Meta.ppExpr value}"
+          else if let .some { mvarIdPending, .. } ← getDelayedMVarAssignment? mvarId then
+            pure s!"\n ::= {mvarIdPending.name}"
+          else
+            pure ""
+        else
+          pure ""
+      pure $ (String.join resultFVars) ++ resultMain ++ resultValue
+    printFVar (fvarId: FVarId) (decl: LocalDecl): MetaM String := do
+      pure s!" | {fvarId.name}{userNameToString decl.userName}: {← Meta.ppExpr decl.type}"
+    userNameToString : Name → String
+      | .anonymous => ""
+      | other => s!"[{other}]"
+    parentHasMVar (mvarId: MVarId): Bool := parent?.map (λ state => state.mctx.decls.contains mvarId) |>.getD true
+
+end Pantograph
diff --git a/Pantograph/Elab.lean b/Pantograph/Elab.lean
new file mode 100644
index 0000000..3c3b3cd
--- /dev/null
+++ b/Pantograph/Elab.lean
@@ -0,0 +1,40 @@
+import Lean
+open Lean
+
+namespace Pantograph
+
+-- Functions for creating contexts and states
+@[export pantograph_default_elab_context]
+def defaultElabContext: Elab.Term.Context := {
+    errToSorry := false
+  }
+
+/-- Read syntax object from string -/
+def parseTerm (env: Environment) (s: String): Except String Syntax :=
+  Parser.runParserCategory
+    (env := env)
+    (catName := `term)
+    (input := s)
+    (fileName := "<stdin>")
+
+def parseTermM [Monad m] [MonadEnv m] (s: String): m (Except String Syntax) := do
+  return Parser.runParserCategory
+    (env := ← MonadEnv.getEnv)
+    (catName := `term)
+    (input := s)
+    (fileName := "<stdin>")
+
+/-- Parse a syntax object. May generate additional metavariables! -/
+def elabType (syn: Syntax): Elab.TermElabM (Except String Expr) := do
+  try
+    let expr ← Elab.Term.elabType syn
+    return .ok expr
+  catch ex => return .error (← ex.toMessageData.toString)
+def elabTerm (syn: Syntax) (expectedType? : Option Expr := .none): Elab.TermElabM (Except String Expr) := do
+  try
+    let expr ← Elab.Term.elabTerm (stx := syn) expectedType?
+    return .ok expr
+  catch ex => return .error (← ex.toMessageData.toString)
+
+
+end Pantograph
diff --git a/Pantograph/Environment.lean b/Pantograph/Environment.lean
index 040d801..ad21284 100644
--- a/Pantograph/Environment.lean
+++ b/Pantograph/Environment.lean
@@ -1,6 +1,9 @@
+import Pantograph.Delate
+import Pantograph.Elab
 import Pantograph.Protocol
 import Pantograph.Serial
-import Lean
+import Lean.Environment
+import Lean.Replay
 
 open Lean
 open Pantograph
diff --git a/Pantograph/Expr.lean b/Pantograph/Expr.lean
deleted file mode 100644
index a13ffec..0000000
--- a/Pantograph/Expr.lean
+++ /dev/null
@@ -1,162 +0,0 @@
-import Lean
-import Std.Data.HashMap
-
-open Lean
-
-namespace Pantograph
-
-structure ProjectionApplication where
-  projector: Name
-  numParams: Nat
-  inner: Expr
-
-@[export pantograph_expr_proj_to_app]
-def exprProjToApp (env: Environment) (e: Expr): ProjectionApplication :=
-  let (typeName, idx, inner) := match e with
-    | .proj typeName idx inner => (typeName, idx, inner)
-    | _ => panic! "Argument must be proj"
-  let ctor := getStructureCtor env typeName
-  let fieldName := getStructureFields env typeName |>.get! idx
-  let projector := getProjFnForField? env typeName fieldName |>.get!
-  {
-    projector,
-    numParams := ctor.numParams,
-    inner,
-  }
-
-def _root_.Lean.Name.isAuxLemma (n : Lean.Name) : Bool := n matches .num (.str _ "_auxLemma") _
-
-/-- Unfold all lemmas created by `Lean.Meta.mkAuxLemma`. These end in `_auxLemma.nn` where `nn` is a number. -/
-@[export pantograph_unfold_aux_lemmas]
-def unfoldAuxLemmas (e : Expr) : CoreM Expr := do
-  Lean.Meta.deltaExpand e Lean.Name.isAuxLemma
-
-/--
-Force the instantiation of delayed metavariables even if they cannot be fully
-instantiated. This is used during resumption to provide diagnostic data about
-the current goal.
-
-Since Lean 4 does not have an `Expr` constructor corresponding to delayed
-metavariables, any delayed metavariables must be recursively handled by this
-function to ensure that nested delayed metavariables can be properly processed.
-The caveat is this recursive call will lead to infinite recursion if a loop
-between metavariable assignment exists.
-
-This function ensures any metavariable in the result is either
-1. Delayed assigned with its pending mvar not assigned in any form
-2. Not assigned (delay or not)
- -/
-partial def instantiateDelayedMVars (eOrig: Expr) : MetaM Expr := do
-  --let padding := String.join $ List.replicate level "│ "
-  --IO.println s!"{padding}Starting {toString eOrig}"
-  let mut result ← Meta.transform (← instantiateMVars eOrig)
-    (pre := fun e => e.withApp fun f args => do
-      let .mvar mvarId := f | return .continue
-      --IO.println s!"{padding}├V {e}"
-      let mvarDecl ← mvarId.getDecl
-
-      -- This is critical to maintaining the interdependency of metavariables.
-      -- Without setting `.syntheticOpaque`, Lean's metavariable elimination
-      -- system will not make the necessary delayed assigned mvars in case of
-      -- nested mvars.
-      mvarId.setKind .syntheticOpaque
-
-      mvarId.withContext do
-        let lctx ← MonadLCtx.getLCtx
-        if mvarDecl.lctx.any (λ decl => !lctx.contains decl.fvarId) then
-          let violations := mvarDecl.lctx.decls.foldl (λ acc decl? => match decl? with
-            | .some decl => if lctx.contains decl.fvarId then acc else acc ++ [decl.fvarId.name]
-            | .none => acc) []
-          panic! s!"In the context of {mvarId.name}, there are local context variable violations: {violations}"
-
-        if let .some assign ← getExprMVarAssignment? mvarId then
-          --IO.println s!"{padding}├A ?{mvarId.name}"
-          assert! !(← mvarId.isDelayedAssigned)
-          return .visit (mkAppN assign args)
-        else if let some { fvars, mvarIdPending } ← getDelayedMVarAssignment? mvarId then
-          --let substTableStr := String.intercalate ", " $ Array.zipWith fvars args (λ fvar assign => s!"{fvar.fvarId!.name} := {assign}") |>.toList
-          --IO.println s!"{padding}├MD ?{mvarId.name} := ?{mvarIdPending.name} [{substTableStr}]"
-
-          if args.size < fvars.size then
-            throwError "Not enough arguments to instantiate a delay assigned mvar. This is due to bad implementations of a tactic: {args.size} < {fvars.size}. Expr: {toString e}; Origin: {toString eOrig}"
-          --if !args.isEmpty then
-            --IO.println s!"{padding}├── Arguments Begin"
-          let args ← args.mapM self
-          --if !args.isEmpty then
-            --IO.println s!"{padding}├── Arguments End"
-          if !(← mvarIdPending.isAssignedOrDelayedAssigned) then
-            --IO.println s!"{padding}├T1"
-            let result := mkAppN f args
-            return .done result
-
-          let pending ← mvarIdPending.withContext do
-            let inner ← instantiateDelayedMVars (.mvar mvarIdPending) --(level := level + 1)
-            --IO.println s!"{padding}├Pre: {inner}"
-            pure <| (← inner.abstractM fvars).instantiateRev args
-
-          -- Tail arguments
-          let result := mkAppRange pending fvars.size args.size args
-          --IO.println s!"{padding}├MD {result}"
-          return .done result
-        else
-          assert! !(← mvarId.isAssigned)
-          assert! !(← mvarId.isDelayedAssigned)
-          --if !args.isEmpty then
-          --  IO.println s!"{padding}├── Arguments Begin"
-          let args ← args.mapM self
-          --if !args.isEmpty then
-          --  IO.println s!"{padding}├── Arguments End"
-
-          --IO.println s!"{padding}├M ?{mvarId.name}"
-          return .done (mkAppN f args))
-  --IO.println s!"{padding}└Result {result}"
-  return result
-  where
-  self e := instantiateDelayedMVars e --(level := level + 1)
-
-/--
-Convert an expression to an equiavlent form with
-1. No nested delayed assigned mvars
-2. No aux lemmas
-3. No assigned mvars
- -/
-@[export pantograph_instantiate_all_m]
-def instantiateAll (e: Expr): MetaM Expr := do
-  let e ← instantiateDelayedMVars e
-  let e ← unfoldAuxLemmas e
-  return e
-
-structure DelayedMVarInvocation where
-  mvarIdPending: MVarId
-  args: Array (FVarId × (Option Expr))
-  -- Extra arguments applied to the result of this substitution
-  tail: Array Expr
-
--- The pending mvar of any delayed assigned mvar must not be assigned in any way.
-@[export pantograph_to_delayed_mvar_invocation_m]
-def toDelayedMVarInvocation (e: Expr): MetaM (Option DelayedMVarInvocation) := do
-  let .mvar mvarId := e.getAppFn | return .none
-  let .some decl ← getDelayedMVarAssignment? mvarId | return .none
-  let mvarIdPending := decl.mvarIdPending
-  let mvarDecl ← mvarIdPending.getDecl
-  -- Print the function application e. See Lean's `withOverApp`
-  let args := e.getAppArgs
-
-  assert! args.size ≥ decl.fvars.size
-  assert! !(← mvarIdPending.isAssigned)
-  assert! !(← mvarIdPending.isDelayedAssigned)
-  let fvarArgMap: Std.HashMap FVarId Expr := Std.HashMap.ofList $ (decl.fvars.map (·.fvarId!) |>.zip args).toList
-  let subst ← mvarDecl.lctx.foldlM (init := []) λ acc localDecl => do
-    let fvarId := localDecl.fvarId
-    let a := fvarArgMap[fvarId]?
-    return acc ++ [(fvarId, a)]
-
-  assert! decl.fvars.all (λ fvar => mvarDecl.lctx.findFVar? fvar |>.isSome)
-
-  return .some {
-    mvarIdPending,
-    args := subst.toArray,
-    tail := args.toList.drop decl.fvars.size |>.toArray,
-  }
-
-end Pantograph
diff --git a/Pantograph/Library.lean b/Pantograph/Library.lean
index 23a2046..20c7c9b 100644
--- a/Pantograph/Library.lean
+++ b/Pantograph/Library.lean
@@ -1,8 +1,7 @@
-import Pantograph.Condensed
 import Pantograph.Environment
 import Pantograph.Goal
 import Pantograph.Protocol
-import Pantograph.Serial
+import Pantograph.Delate
 import Pantograph.Version
 import Lean
 
@@ -42,7 +41,7 @@ namespace Pantograph
 def runMetaM { α } (metaM: MetaM α): CoreM α :=
   metaM.run'
 def runTermElabM { α } (termElabM: Elab.TermElabM α): CoreM α :=
-  termElabM.run' (ctx := Condensed.elabContext) |>.run'
+  termElabM.run' (ctx := defaultElabContext) |>.run'
 
 def errorI (type desc: String): Protocol.InteractionError := { error := type, desc := desc }
 
diff --git a/Pantograph/Protocol.lean b/Pantograph/Protocol.lean
index 2ba073e..08c67ef 100644
--- a/Pantograph/Protocol.lean
+++ b/Pantograph/Protocol.lean
@@ -183,6 +183,12 @@ structure EnvAdd where
 structure EnvAddResult where
   deriving Lean.ToJson
 
+structure EnvSaveLoad where
+  path: System.FilePath
+  deriving Lean.FromJson
+structure EnvSaveLoadResult where
+  deriving Lean.ToJson
+
 /-- Set options; See `Options` struct above for meanings -/
 structure OptionsSet where
   printJsonPretty?: Option Bool
diff --git a/Pantograph/Serial.lean b/Pantograph/Serial.lean
index 3a9efa4..2f04bdb 100644
--- a/Pantograph/Serial.lean
+++ b/Pantograph/Serial.lean
@@ -1,362 +1,73 @@
-/-
-All serialisation functions;
-This replicates the behaviour of `Scope`s in `Lean/Elab/Command.lean` without
-using `Scope`s.
+import Lean.Environment
+import Lean.Replay
+import Init.System.IOError
+import Std.Data.HashMap
+
+/-!
+Input/Output functions
+
+# Pickling and unpickling objects
+
+By abusing `saveModuleData` and `readModuleData` we can pickle and unpickle objects to disk.
 -/
-import Lean
-import Pantograph.Condensed
-import Pantograph.Expr
-import Pantograph.Goal
-import Pantograph.Protocol
 
 open Lean
 
--- Symbol processing functions --
-
 namespace Pantograph
 
-
---- Input Functions ---
-
-/-- Read syntax object from string -/
-def parseTerm (env: Environment) (s: String): Except String Syntax :=
-  Parser.runParserCategory
-    (env := env)
-    (catName := `term)
-    (input := s)
-    (fileName := "<stdin>")
-
-def parseTermM [Monad m] [MonadEnv m] (s: String): m (Except String Syntax) := do
-  return Parser.runParserCategory
-    (env := ← MonadEnv.getEnv)
-    (catName := `term)
-    (input := s)
-    (fileName := "<stdin>")
-
-/-- Parse a syntax object. May generate additional metavariables! -/
-def elabType (syn: Syntax): Elab.TermElabM (Except String Expr) := do
-  try
-    let expr ← Elab.Term.elabType syn
-    return .ok expr
-  catch ex => return .error (← ex.toMessageData.toString)
-def elabTerm (syn: Syntax) (expectedType? : Option Expr := .none): Elab.TermElabM (Except String Expr) := do
-  try
-    let expr ← Elab.Term.elabTerm (stx := syn) expectedType?
-    return .ok expr
-  catch ex => return .error (← ex.toMessageData.toString)
-
-
---- Output Functions ---
-
-def typeExprToBound (expr: Expr): MetaM Protocol.BoundExpression := do
-  Meta.forallTelescope expr fun arr body => do
-    let binders ← arr.mapM fun fvar => do
-      return (toString (← fvar.fvarId!.getUserName), toString (← Meta.ppExpr (← fvar.fvarId!.getType)))
-    return { binders, target := toString (← Meta.ppExpr body) }
-
-def serializeName (name: Name) (sanitize: Bool := true): String :=
-  let internal := name.isInaccessibleUserName || name.hasMacroScopes
-  if sanitize && internal then "_"
-  else toString name |> addQuotes
-  where
-  addQuotes (n: String) :=
-    let quote := "\""
-    if n.contains Lean.idBeginEscape then s!"{quote}{n}{quote}" else n
-
-/-- serialize a sort level. Expression is optimized to be compact e.g. `(+ u 2)` -/
-partial def serializeSortLevel (level: Level) (sanitize: Bool): String :=
-  let k := level.getOffset
-  let u := level.getLevelOffset
-  let u_str := match u with
-    | .zero => "0"
-    | .succ _ => panic! "getLevelOffset should not return .succ"
-    | .max v w =>
-      let v := serializeSortLevel v sanitize
-      let w := serializeSortLevel w sanitize
-      s!"(:max {v} {w})"
-    | .imax v w =>
-      let v := serializeSortLevel v sanitize
-      let w := serializeSortLevel w sanitize
-      s!"(:imax {v} {w})"
-    | .param name =>
-      let name := serializeName name sanitize
-      s!"{name}"
-    | .mvar id =>
-      let name := serializeName id.name sanitize
-      s!"(:mv {name})"
-  match k, u with
-  | 0, _ => u_str
-  | _, .zero => s!"{k}"
-  | _, _ => s!"(+ {u_str} {k})"
-
+/--
+Save an object to disk.
+If you need to write multiple objects from within a single declaration,
+you will need to provide a unique `key` for each.
+-/
+def pickle {α : Type} (path : System.FilePath) (x : α) (key : Name := by exact decl_name%) : IO Unit :=
+  saveModuleData path key (unsafe unsafeCast x)
 
 /--
- Completely serializes an expression tree. Json not used due to compactness
+Load an object from disk.
+Note: The returned `CompactedRegion` can be used to free the memory behind the value
+of type `α`, using `CompactedRegion.free` (which is only safe once all references to the `α` are
+released). Ignoring the `CompactedRegion` results in the data being leaked.
+Use `withUnpickle` to call `CompactedRegion.free` automatically.
 
-A `_` symbol in the AST indicates automatic deductions not present in the original expression.
+This function is unsafe because the data being loaded may not actually have type `α`, and this
+may cause crashes or other bad behavior.
 -/
-partial def serializeExpressionSexp (expr: Expr) (sanitize: Bool := true): MetaM String := do
-  self expr
-  where
-  delayedMVarToSexp (e: Expr): MetaM (Option String) := do
-    let .some invocation ← toDelayedMVarInvocation e | return .none
-    let callee ← self $ .mvar invocation.mvarIdPending
-    let sites ← invocation.args.mapM (λ (fvarId, arg) => do
-        let arg := match arg with
-          | .some arg => arg
-          | .none => .fvar fvarId
-        self arg
-      )
-    let tailArgs ← invocation.tail.mapM self
+unsafe def unpickle (α : Type) (path : System.FilePath) : IO (α × CompactedRegion) := do
+  let (x, region) ← readModuleData path
+  pure (unsafeCast x, region)
 
-    let sites := " ".intercalate sites.toList
-    let result := if tailArgs.isEmpty then
-        s!"(:subst {callee} {sites})"
-      else
-        let tailArgs := " ".intercalate tailArgs.toList
-        s!"((:subst {callee} {sites}) {tailArgs})"
-    return .some result
+/-- Load an object from disk and run some continuation on it, freeing memory afterwards. -/
+unsafe def withUnpickle [Monad m] [MonadLiftT IO m] {α β : Type}
+    (path : System.FilePath) (f : α → m β) : m β := do
+  let (x, region) ← unpickle α path
+  let r ← f x
+  region.free
+  pure r
 
-  self (e: Expr): MetaM String := do
-    if let .some result ← delayedMVarToSexp e then
-      return result
-    match e with
-    | .bvar deBruijnIndex =>
-      -- This is very common so the index alone is shown. Literals are handled below.
-      -- The raw de Bruijn index should never appear in an unbound setting. In
-      -- Lean these are handled using a `#` prefix.
-      pure s!"{deBruijnIndex}"
-    | .fvar fvarId =>
-      let name := ofName fvarId.name
-      pure s!"(:fv {name})"
-    | .mvar mvarId => do
-        let pref := if ← mvarId.isDelayedAssigned then "mvd" else "mv"
-        let name := ofName mvarId.name
-        pure s!"(:{pref} {name})"
-    | .sort level =>
-      let level := serializeSortLevel level sanitize
-      pure s!"(:sort {level})"
-    | .const declName _ =>
-      -- The universe level of the const expression is elided since it should be
-      -- inferrable from surrounding expression
-      pure s!"(:c {declName})"
-    | .app _ _ => do
-      let fn' ← self e.getAppFn
-      let args := (← e.getAppArgs.mapM self) |>.toList
-      let args := " ".intercalate args
-      pure s!"({fn'} {args})"
-    | .lam binderName binderType body binderInfo => do
-      let binderName' := ofName binderName
-      let binderType' ← self binderType
-      let body' ← self body
-      let binderInfo' := binderInfoSexp binderInfo
-      pure s!"(:lambda {binderName'} {binderType'} {body'}{binderInfo'})"
-    | .forallE binderName binderType body binderInfo => do
-      let binderName' := ofName binderName
-      let binderType' ← self binderType
-      let body' ← self body
-      let binderInfo' := binderInfoSexp binderInfo
-      pure s!"(:forall {binderName'} {binderType'} {body'}{binderInfo'})"
-    | .letE name type value body _ => do
-      -- Dependent boolean flag diacarded
-      let name' := serializeName name
-      let type' ← self type
-      let value' ← self value
-      let body' ← self body
-      pure s!"(:let {name'} {type'} {value'} {body'})"
-    | .lit v =>
-      -- To not burden the downstream parser who needs to handle this, the literal
-      -- is wrapped in a :lit sexp.
-      let v' := match v with
-        | .natVal val => toString val
-        | .strVal val => s!"\"{val}\""
-      pure s!"(:lit {v'})"
-    | .mdata _ inner =>
-      -- NOTE: Equivalent to expr itself, but mdata influences the prettyprinter
-      -- It may become necessary to incorporate the metadata.
-      self inner
-    | .proj _ _ _ => do
-      let env ← getEnv
-      let projApp := exprProjToApp env e
-      let autos := String.intercalate " " (List.replicate projApp.numParams "_")
-      let inner ← self projApp.inner
-      pure s!"((:c {projApp.projector}) {autos} {inner})"
-  -- Elides all unhygenic names
-  binderInfoSexp : Lean.BinderInfo → String
-    | .default => ""
-    | .implicit => " :implicit"
-    | .strictImplicit => " :strictImplicit"
-    | .instImplicit => " :instImplicit"
-  ofName (name: Name) := serializeName name sanitize
+/--
+Pickle an `Environment` to disk.
 
-def serializeExpression (options: @&Protocol.Options) (e: Expr): MetaM Protocol.Expression := do
-  let pp?: Option String ← match options.printExprPretty with
-    | true => pure $ .some $ toString $ ← Meta.ppExpr e
-    | false => pure $ .none
-  let sexp?: Option String ← match options.printExprAST with
-    | true => pure $ .some $ ← serializeExpressionSexp e
-    | false => pure $ .none
-  let dependentMVars? ← match options.printDependentMVars with
-    | true => pure $ .some $ (← Meta.getMVars e).map (λ mvarId => mvarId.name.toString)
-    | false => pure $ .none
-  return {
-    pp?,
-    sexp?
-    dependentMVars?,
-  }
+We only store:
+* the list of imports
+* the new constants from `Environment.constants`
+and when unpickling, we build a fresh `Environment` from the imports,
+and then add the new constants.
+-/
+@[export pantograph_env_pickle_m]
+def env_pickle (env : Environment) (path : System.FilePath) : IO Unit :=
+  Pantograph.pickle path (env.header.imports, env.constants.map₂)
 
+/--
+Unpickle an `Environment` from disk.
 
-/-- Adapted from ppGoal -/
-def serializeGoal (options: @&Protocol.Options) (goal: MVarId) (mvarDecl: MetavarDecl) (parentDecl?: Option MetavarDecl := .none)
-      : MetaM Protocol.Goal := do
-  -- Options for printing; See Meta.ppGoal for details
-  let showLetValues  := true
-  let ppAuxDecls     := options.printAuxDecls
-  let ppImplDetailHyps := options.printImplementationDetailHyps
-  let lctx           := mvarDecl.lctx
-  let lctx           := lctx.sanitizeNames.run' { options := (← getOptions) }
-  Meta.withLCtx lctx mvarDecl.localInstances do
-    let ppVarNameOnly (localDecl: LocalDecl): MetaM Protocol.Variable := do
-      match localDecl with
-      | .cdecl _ fvarId userName _ _ _ =>
-        return {
-          name := ofName fvarId.name,
-          userName:= ofName userName.simpMacroScopes,
-          isInaccessible := userName.isInaccessibleUserName
-        }
-      | .ldecl _ fvarId userName _ _ _ _ => do
-        return {
-          name := ofName fvarId.name,
-          userName := toString userName.simpMacroScopes,
-          isInaccessible := userName.isInaccessibleUserName
-        }
-    let ppVar (localDecl : LocalDecl) : MetaM Protocol.Variable := do
-      match localDecl with
-      | .cdecl _ fvarId userName type _ _ =>
-        let userName := userName.simpMacroScopes
-        let type ← instantiate type
-        return {
-          name := ofName fvarId.name,
-          userName:= ofName userName,
-          isInaccessible := userName.isInaccessibleUserName
-          type? := .some (← serializeExpression options type)
-        }
-      | .ldecl _ fvarId userName type val _ _ => do
-        let userName := userName.simpMacroScopes
-        let type ← instantiate type
-        let value? ← if showLetValues then
-          let val ← instantiate val
-          pure $ .some (← serializeExpression options val)
-        else
-          pure $ .none
-        return {
-          name := ofName fvarId.name,
-          userName:= ofName userName,
-          isInaccessible := userName.isInaccessibleUserName
-          type? := .some (← serializeExpression options 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 nameOnly := options.noRepeat && (parentDecl?.map
-          (λ decl => decl.lctx.find? localDecl.fvarId |>.isSome) |>.getD false)
-        let var ← match nameOnly with
-          | true => ppVarNameOnly localDecl
-          | false => ppVar localDecl
-        return var::acc
-    return {
-      name := ofName goal.name,
-      userName? := if mvarDecl.userName == .anonymous then .none else .some (ofName mvarDecl.userName),
-      isConversion := isLHSGoal? mvarDecl.type |>.isSome,
-      target := (← serializeExpression options (← instantiate mvarDecl.type)),
-      vars := vars.reverse.toArray
-    }
-  where
-  instantiate := instantiateAll
-  ofName (n: Name) := serializeName n (sanitize := false)
-
-protected def GoalState.serializeGoals
-      (state: GoalState)
-      (parent: Option GoalState := .none)
-      (options: @&Protocol.Options := {}):
-    MetaM (Array Protocol.Goal):= do
-  state.restoreMetaM
-  let goals := state.goals.toArray
-  let parentDecl? := parent.bind (λ parentState => parentState.mctx.findDecl? state.parentMVar?.get!)
-  goals.mapM fun goal => do
-    match state.mctx.findDecl? goal with
-    | .some mvarDecl =>
-      let serializedGoal ← serializeGoal options goal mvarDecl (parentDecl? := parentDecl?)
-      pure serializedGoal
-    | .none => throwError s!"Metavariable does not exist in context {goal.name}"
-
-/-- Print the metavariables in a readable format -/
-@[export pantograph_goal_state_diag_m]
-protected def GoalState.diag (goalState: GoalState) (parent?: Option GoalState := .none) (options: Protocol.GoalDiag := {}): CoreM String := do
-  let metaM: MetaM String := do
-    goalState.restoreMetaM
-    let savedState := goalState.savedState
-    let goals := savedState.tactic.goals
-    let mctx ← getMCtx
-    let root := goalState.root
-    -- Print the root
-    let result: String ← match mctx.decls.find? root with
-      | .some decl => printMVar ">" root decl
-      | .none => pure s!">{root.name}: ??"
-    let resultGoals ← goals.filter (· != root) |>.mapM (fun mvarId =>
-      match mctx.decls.find? mvarId with
-      | .some decl => printMVar "⊢" mvarId decl
-      | .none => pure s!"⊢{mvarId.name}: ??"
-    )
-    let goals := goals.toSSet
-    let resultOthers ← mctx.decls.toList.filter (λ (mvarId, _) =>
-        !(goals.contains mvarId || mvarId == root) && options.printAll)
-        |>.mapM (fun (mvarId, decl) => do
-          let pref := if parentHasMVar mvarId then " " else "~"
-          printMVar pref mvarId decl
-        )
-    pure $ result ++ "\n" ++ (resultGoals.map (· ++ "\n") |> String.join) ++ (resultOthers.map (· ++ "\n") |> String.join)
-  metaM.run' {}
-  where
-    printMVar (pref: String) (mvarId: MVarId) (decl: MetavarDecl): MetaM String := mvarId.withContext do
-      let resultFVars: List String ←
-        if options.printContext then
-          decl.lctx.fvarIdToDecl.toList.mapM (λ (fvarId, decl) =>
-            do pure $ (← printFVar fvarId decl) ++ "\n")
-        else
-          pure []
-      let type ← if options.instantiate
-        then instantiateAll decl.type
-        else pure $ decl.type
-      let type_sexp ← if options.printSexp then
-          let sexp ← serializeExpressionSexp type (sanitize := false)
-          pure <| " " ++ sexp
-        else
-          pure ""
-      let resultMain: String := s!"{pref}{mvarId.name}{userNameToString decl.userName}: {← Meta.ppExpr decl.type}{type_sexp}"
-      let resultValue: String ←
-        if options.printValue then
-          if let .some value ← getExprMVarAssignment? mvarId then
-            let value ← if options.instantiate
-              then instantiateAll value
-              else pure $ value
-            pure s!"\n := {← Meta.ppExpr value}"
-          else if let .some { mvarIdPending, .. } ← getDelayedMVarAssignment? mvarId then
-            pure s!"\n ::= {mvarIdPending.name}"
-          else
-            pure ""
-        else
-          pure ""
-      pure $ (String.join resultFVars) ++ resultMain ++ resultValue
-    printFVar (fvarId: FVarId) (decl: LocalDecl): MetaM String := do
-      pure s!" | {fvarId.name}{userNameToString decl.userName}: {← Meta.ppExpr decl.type}"
-    userNameToString : Name → String
-      | .anonymous => ""
-      | other => s!"[{other}]"
-    parentHasMVar (mvarId: MVarId): Bool := parent?.map (λ state => state.mctx.decls.contains mvarId) |>.getD true
+We construct a fresh `Environment` with the relevant imports,
+and then replace the new constants.
+-/
+@[export pantograph_env_unpickle_m]
+def env_unpickle (path : System.FilePath) : IO (Environment × CompactedRegion) := unsafe do
+  let ((imports, map₂), region) ← Pantograph.unpickle (Array Import × PHashMap Name ConstantInfo) path
+  let env ← importModules imports {} 0
+  return (← env.replay (Std.HashMap.ofList map₂.toList), region)
 
 end Pantograph
diff --git a/Repl.lean b/Repl.lean
index 7e8f0e4..e162f05 100644
--- a/Repl.lean
+++ b/Repl.lean
@@ -22,8 +22,9 @@ abbrev CR α := Except Protocol.InteractionError α
 def runMetaInMainM { α } (metaM: Lean.MetaM α): MainM α :=
   metaM.run'
 def runTermElabInMainM { α } (termElabM: Lean.Elab.TermElabM α) : MainM α :=
-  termElabM.run' (ctx := Condensed.elabContext) |>.run'
+  termElabM.run' (ctx := defaultElabContext) |>.run'
 
+/-- Main loop command of the REPL -/
 def execute (command: Protocol.Command): MainM Lean.Json := do
   let run { α β: Type } [Lean.FromJson α] [Lean.ToJson β] (comm: α → MainM (CR β)): MainM Lean.Json :=
     match Lean.fromJson? command.payload with
@@ -32,28 +33,35 @@ def execute (command: Protocol.Command): MainM Lean.Json := do
       | .ok result =>  return Lean.toJson result
       | .error ierror => return Lean.toJson ierror
     | .error error => return Lean.toJson $ errorCommand s!"Unable to parse json: {error}"
-  match command.cmd with
-  | "reset"         => run reset
-  | "stat"          => run stat
-  | "expr.echo"     => run expr_echo
-  | "env.catalog"   => run env_catalog
-  | "env.inspect"   => run env_inspect
-  | "env.add"       => run env_add
-  | "options.set"   => run options_set
-  | "options.print" => run options_print
-  | "goal.start"    => run goal_start
-  | "goal.tactic"   => run goal_tactic
-  | "goal.continue" => run goal_continue
-  | "goal.delete"   => run goal_delete
-  | "goal.print"    => run goal_print
-  | "frontend.process"  => run frontend_process
-  | cmd =>
-    let error: Protocol.InteractionError :=
-      errorCommand s!"Unknown command {cmd}"
-    return Lean.toJson error
+  try
+    match command.cmd with
+    | "reset"         => run reset
+    | "stat"          => run stat
+    | "expr.echo"     => run expr_echo
+    | "env.catalog"   => run env_catalog
+    | "env.inspect"   => run env_inspect
+    | "env.add"       => run env_add
+    | "env.save"      => run env_save
+    | "env.load"      => run env_load
+    | "options.set"   => run options_set
+    | "options.print" => run options_print
+    | "goal.start"    => run goal_start
+    | "goal.tactic"   => run goal_tactic
+    | "goal.continue" => run goal_continue
+    | "goal.delete"   => run goal_delete
+    | "goal.print"    => run goal_print
+    | "frontend.process"  => run frontend_process
+    | cmd =>
+      let error: Protocol.InteractionError :=
+        errorCommand s!"Unknown command {cmd}"
+      return Lean.toJson error
+  catch ex => do
+    let error ← ex.toMessageData.toString
+    return Lean.toJson $ errorIO error
   where
   errorCommand := errorI "command"
   errorIndex := errorI "index"
+  errorIO := errorI "io"
   newGoalState (goalState: GoalState) : MainM Nat := do
     let state ← get
     let stateId := state.nextId
@@ -80,6 +88,14 @@ def execute (command: Protocol.Command): MainM Lean.Json := do
     Environment.inspect args state.options
   env_add (args: Protocol.EnvAdd): MainM (CR Protocol.EnvAddResult) := do
     Environment.addDecl args
+  env_save (args: Protocol.EnvSaveLoad): MainM (CR Protocol.EnvSaveLoadResult) := do
+    let env ← Lean.MonadEnv.getEnv
+    env_pickle env args.path
+    return .ok {}
+  env_load (args: Protocol.EnvSaveLoad): MainM (CR Protocol.EnvSaveLoadResult) := do
+    let (env, _) ← env_unpickle args.path
+    Lean.setEnv env
+    return .ok {}
   expr_echo (args: Protocol.ExprEcho): MainM (CR Protocol.ExprEchoResult) := do
     let state ← get
     exprEcho args.expr (expectedType? := args.type?) (levels := args.levels.getD #[]) (options := state.options)
diff --git a/Test/Common.lean b/Test/Common.lean
index 2d98aca..3998293 100644
--- a/Test/Common.lean
+++ b/Test/Common.lean
@@ -1,7 +1,6 @@
 import Pantograph.Goal
 import Pantograph.Library
 import Pantograph.Protocol
-import Pantograph.Condensed
 import Lean
 import LSpec
 
@@ -90,9 +89,9 @@ def runCoreMSeq (env: Environment) (coreM: CoreM LSpec.TestSeq) (options: Array
 def runMetaMSeq (env: Environment) (metaM: MetaM LSpec.TestSeq): IO LSpec.TestSeq :=
   runCoreMSeq env metaM.run'
 def runTermElabMInMeta { α } (termElabM: Lean.Elab.TermElabM α): Lean.MetaM α :=
-  termElabM.run' (ctx := Condensed.elabContext)
+  termElabM.run' (ctx := defaultElabContext)
 def runTermElabMSeq (env: Environment) (termElabM: Elab.TermElabM LSpec.TestSeq): IO LSpec.TestSeq :=
-  runMetaMSeq env $ termElabM.run' (ctx := Condensed.elabContext)
+  runMetaMSeq env $ termElabM.run' (ctx := defaultElabContext)
 
 def exprToStr (e: Expr): Lean.MetaM String := toString <$> Meta.ppExpr e
 
diff --git a/Test/Serial.lean b/Test/Delate.lean
similarity index 96%
rename from Test/Serial.lean
rename to Test/Delate.lean
index 1c00501..227ab24 100644
--- a/Test/Serial.lean
+++ b/Test/Delate.lean
@@ -1,10 +1,10 @@
 import LSpec
-import Pantograph.Serial
+import Pantograph.Delate
 import Test.Common
 import Lean
 
 open Lean
-namespace Pantograph.Test.Serial
+namespace Pantograph.Test.Delate
 
 open Pantograph
 
@@ -64,7 +64,7 @@ def test_sexp_of_elab (env: Environment): IO LSpec.TestSeq := do
         | .ok expr => pure expr
         | .error e => return elabFailure e
       return LSpec.check source ((← serializeExpressionSexp expr) = target)
-    let metaM := (Elab.Term.withLevelNames levels termElabM).run' (ctx := Condensed.elabContext)
+    let metaM := (Elab.Term.withLevelNames levels termElabM).run' (ctx := defaultElabContext)
     return LSpec.TestSeq.append suites (← runMetaMSeq env metaM))
     LSpec.TestSeq.done
 
@@ -85,7 +85,7 @@ def test_sexp_of_expr (env: Environment): IO LSpec.TestSeq := do
     let testCaseName := target.take 10
     let test := LSpec.check   testCaseName ((← serializeExpressionSexp expr) = target)
     return LSpec.TestSeq.append suites test) LSpec.TestSeq.done
-  runMetaMSeq env $ termElabM.run' (ctx := Condensed.elabContext)
+  runMetaMSeq env $ termElabM.run' (ctx := defaultElabContext)
 
 -- Instance parsing
 def test_instance (env: Environment): IO LSpec.TestSeq :=
@@ -106,4 +106,4 @@ def suite (env: Environment): List (String × IO LSpec.TestSeq) :=
     ("Instance", test_instance env),
   ]
 
-end Pantograph.Test.Serial
+end Pantograph.Test.Delate
diff --git a/Test/Environment.lean b/Test/Environment.lean
index 6b418f7..79d04ed 100644
--- a/Test/Environment.lean
+++ b/Test/Environment.lean
@@ -1,5 +1,5 @@
 import LSpec
-import Pantograph.Serial
+import Pantograph.Delate
 import Pantograph.Environment
 import Test.Common
 import Lean
diff --git a/Test/Main.lean b/Test/Main.lean
index 0fde5fa..25bb0d9 100644
--- a/Test/Main.lean
+++ b/Test/Main.lean
@@ -5,7 +5,7 @@ import Test.Integration
 import Test.Library
 import Test.Metavar
 import Test.Proofs
-import Test.Serial
+import Test.Delate
 import Test.Tactic
 
 -- Test running infrastructure
@@ -50,7 +50,7 @@ def main (args: List String) := do
     ("Library", Library.suite env_default),
     ("Metavar", Metavar.suite env_default),
     ("Proofs", Proofs.suite env_default),
-    ("Serial", Serial.suite env_default),
+    ("Delate", Delate.suite env_default),
     ("Tactic/Congruence", Tactic.Congruence.suite env_default),
     ("Tactic/Motivated Apply", Tactic.MotivatedApply.suite env_default),
     ("Tactic/No Confuse", Tactic.NoConfuse.suite env_default),
diff --git a/Test/Metavar.lean b/Test/Metavar.lean
index dbaf2cc..506e963 100644
--- a/Test/Metavar.lean
+++ b/Test/Metavar.lean
@@ -1,6 +1,6 @@
 import LSpec
 import Pantograph.Goal
-import Pantograph.Serial
+import Pantograph.Delate
 import Test.Common
 import Lean
 
@@ -66,7 +66,7 @@ def proofRunner (env: Lean.Environment) (tests: TestM Unit): IO LSpec.TestSeq :=
   let termElabM := tests.run LSpec.TestSeq.done |>.run {} -- with default options
 
   let coreContext: Lean.Core.Context ← createCoreContext #[]
-  let metaM := termElabM.run' (ctx := Condensed.elabContext)
+  let metaM := termElabM.run' (ctx := defaultElabContext)
   let coreM := metaM.run'
   match ← (coreM.run' coreContext { env := env }).toBaseIO with
   | .error exception =>
diff --git a/Test/Proofs.lean b/Test/Proofs.lean
index 1da21ae..8e3e2a2 100644
--- a/Test/Proofs.lean
+++ b/Test/Proofs.lean
@@ -3,7 +3,7 @@ Tests pertaining to goals with no interdependencies
 -/
 import LSpec
 import Pantograph.Goal
-import Pantograph.Serial
+import Pantograph.Delate
 import Test.Common
 
 namespace Pantograph.Test.Proofs
@@ -74,7 +74,7 @@ def proofRunner (env: Lean.Environment) (tests: TestM Unit): IO LSpec.TestSeq :=
   let termElabM := tests.run LSpec.TestSeq.done |>.run {} -- with default options
 
   let coreContext: Lean.Core.Context ← createCoreContext #[]
-  let metaM := termElabM.run' (ctx := Condensed.elabContext)
+  let metaM := termElabM.run' (ctx := defaultElabContext)
   let coreM := metaM.run'
   match ← (coreM.run' coreContext { env := env }).toBaseIO with
   | .error exception =>