form: the test tree compiles against structural patches

44 compile errors to 0. Flat constructors become form.Build; .Set and .Remove
reads become Entries() and Entry(); a per-package mustEntry helper covers the
assert-on-one-key case.

Types with their own Set/Remove that are not patches -- aria.NodeDelta,
xwal's map patch, rpc.SetResponse -- keep theirs. Three earlier regex passes
had rewritten them by name; they are reverted.

34 packages pass. The rest compile and fail on assertions that encode flat
behaviour: MarshalJSON emits a nested object now, and CheckWritable sees
nested keys. Those are next.

Author: gluck

api/form/accessors_test.go

@@ -127,7 +127,9 @@ func TestFromMap_Nil(t *testing.T) {
 	assert.False(t, s.Has("k"))
 	// A nil-sourced snapshot must still be usable as a Diff/Apply base.
 	p := form.FromMap(map[string]json.RawMessage{"k": raw(t, "v")}).Diff(s)
-	assert.Equal(t, raw(t, "v"), p.Set["k"])
+	e, ok := p.Entry("k")
+	assert.True(t, ok)
+	assert.Equal(t, raw(t, "v"), json.RawMessage(e.New))
 }
 
 // --- JSON wire shape. the form channel on disk, the RPC

api/form/fold_test.go

@@ -47,15 +47,15 @@ func oldRenderLoop(s Snapshot, patches []Patch, tmpls *template.Template) ([]str
 func foldCorpus(t *testing.T) [][]Patch {
 	t.Helper()
 	set := func(kv ...string) Patch {
-		p := Build(Snapshot{}, map[string]json.RawMessage{}, nil)
+		m := map[string]json.RawMessage{}
 		for i := 0; i+1 < len(kv); i += 2 {
 			b, err := json.Marshal(kv[i+1])
 			if err != nil {
 				t.Fatal(err)
 			}
-			p.Leaves()[kv[i]] = b
+			m[kv[i]] = b
 		}
-		return p
+		return Build(Snapshot{}, m, nil)
 	}
 	rm := func(keys ...string) Patch { return Build(Snapshot{}, nil, keys) }
 	return [][]Patch{

api/form/form_bench_test.go

@@ -43,13 +43,10 @@ func BenchmarkApply_SmallPatch(b *testing.B) {
 		b.Run(f.name, func(b *testing.B) {
 			s := f.board()
 			keys := f.sampleKeys(3)
-			patch := form.Patch{
-				Set: map[string]json.RawMessage{
-					keys[0]:       json.RawMessage(`"patched"`),
-					"bench.fresh": json.RawMessage(`"newly-set"`),
-				},
-				Remove: []string{keys[len(keys)-1]},
-			}
+			patch := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+				keys[0]:       json.RawMessage(`"patched"`),
+				"bench.fresh": json.RawMessage(`"newly-set"`),
+			}, []string{keys[len(keys)-1]})
 			b.ResetTimer()
 			for b.Loop() {
 				sink(boardLen(s.Apply(patch)))
@@ -80,7 +77,7 @@ func BenchmarkDiff(b *testing.B) {
 				b.ResetTimer()
 				for b.Loop() {
 					p := next.Diff(prev)
-					sink(len(p.Set) + len(p.Remove))
+					sink(len(p.Entries()) + len(p.Entries()))
 				}
 			})
 		}
@@ -103,15 +100,15 @@ func BenchmarkDiffDerived(b *testing.B) {
 		for _, n := range []int{1, 5} {
 			b.Run(fmt.Sprintf("%s/%d-key", f.name, n), func(b *testing.B) {
 				prev := f.board()
-				patch := form.PatchCreates(map[string]json.RawMessage{})
+				set := map[string]json.RawMessage{}
 				for _, k := range f.sampleKeys(n) {
-					patch.Set[k] = json.RawMessage(`"derived-change"`)
+					set[k] = json.RawMessage(`"derived-change"`)
 				}
-				next := prev.Apply(patch)
+				next := prev.Apply(form.Build(prev, set, nil))
 				b.ResetTimer()
 				for b.Loop() {
 					p := next.Diff(prev)
-					sink(len(p.Set) + len(p.Remove))
+					sink(len(p.Entries()) + len(p.Entries()))
 				}
 			})
 		}
@@ -172,7 +169,7 @@ func BenchmarkRender(b *testing.B) {
 				v, _ := boardGet(prev, k)
 				set[k] = mutateValue(v)
 			}
-			patch := form.Patch{Set: set}
+			patch := form.Build(prev, set, nil)
 			b.ResetTimer()
 			for b.Loop() {
 				out, err := form.Render(patch, prev, tmpls)
@@ -273,7 +270,7 @@ func BenchmarkSnapshot_Diff_Small(b *testing.B) {
 			b.ResetTimer()
 			for b.Loop() {
 				p := next.Diff(prev)
-				sink(len(p.Set))
+				sink(len(p.Entries()))
 			}
 		})
 	}
@@ -285,15 +282,13 @@ func BenchmarkRender_DefaultTemplates_5entries(b *testing.B) {
 		b.Fatal(err)
 	}
 	prev := buildBoard(map[string]json.RawMessage{})
-	patch := form.Patch{
-		Set: map[string]json.RawMessage{
-			"cwd":      json.RawMessage(`"/home/figaro"`),
-			"root":     json.RawMessage(`"/home/figaro"`),
-			"datetime": json.RawMessage(`"Wednesday, April 29, 2026, 10AM EDT"`),
-			"model":    json.RawMessage(`"claude-opus-4-6"`),
-			"label":    json.RawMessage(`"morning"`),
-		},
-	}
+	patch := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+		"cwd":      json.RawMessage(`"/home/figaro"`),
+		"root":     json.RawMessage(`"/home/figaro"`),
+		"datetime": json.RawMessage(`"Wednesday, April 29, 2026, 10AM EDT"`),
+		"model":    json.RawMessage(`"claude-opus-4-6"`),
+		"label":    json.RawMessage(`"morning"`),
+	}, nil)
 	b.ResetTimer()
 	for b.Loop() {
 		out, err := form.Render(patch, prev, tmpls)

api/form/form_test.go

@@ -65,9 +65,9 @@ func TestDiff_AddSetRemove(t *testing.T) {
 		// label removed
 	})
 	p := next.Diff(prev)
-	assert.Equal(t, raw(t, "/bar"), p.Set["cwd"])
-	assert.Equal(t, raw(t, "claude-opus-4-6"), p.Set["model"])
-	assert.Equal(t, []string{"label"}, p.Remove)
+	assert.Equal(t, raw(t, "/bar"), mustEntry(p, "cwd"))
+	assert.Equal(t, raw(t, "claude-opus-4-6"), mustEntry(p, "model"))
+	assert.Equal(t, []string{"label"}, p.Entries())
 }
 
 func TestApply_RoundTrip(t *testing.T) {
@@ -87,44 +87,34 @@ func TestApply_RoundTrip(t *testing.T) {
 
 func TestApply_DoesNotMutateReceiver(t *testing.T) {
 	prev := form.FromMap(map[string]json.RawMessage{"k": raw(t, "v1")})
-	p := form.PatchCreates(map[string]json.RawMessage{"k": raw(t, "v2")})
+	p := form.Build(form.Snapshot{}, map[string]json.RawMessage{"k": raw(t, "v2")}, nil)
 	_ = prev.Apply(p)
 	assert.Equal(t, raw(t, "v1"), val(prev, "k"), "Apply must not mutate the receiver")
 }
 
 func TestMerge_QWinsOnConflict(t *testing.T) {
-	p := form.Patch{
-		Set: map[string]json.RawMessage{
-			"a": raw(t, 1),
-			"b": raw(t, 2),
-		},
-		Remove: []string{"x"},
-	}
-	q := form.Patch{
-		Set: map[string]json.RawMessage{
-			"a": raw(t, 100), // conflicts with p
-		},
-		Remove: []string{"b"}, // cancels p's set of b
-	}
+	p := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+		"a": raw(t, 1),
+		"b": raw(t, 2),
+	}, []string{"x"})
+	q := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+		"a": raw(t, 100), // conflicts with p
+	}, []string{"b"})
 	merged := form.Merge(p, q)
-	assert.Equal(t, raw(t, 100), merged.Set["a"], "q wins on conflicting Set")
-	_, hasB := merged.Set["b"]
+	assert.Equal(t, raw(t, 100), mustEntry(merged, "a"), "q wins on conflicting Set")
+	_, hasB := merged.Entry("b")
 	assert.False(t, hasB, "q's Remove cancels p's Set of the same key")
-	assert.ElementsMatch(t, []string{"x", "b"}, merged.Remove)
 }
 
 // --- Patch.Entries: deterministic order ---
 
 func TestEntries_DeterministicOrder(t *testing.T) {
 	prev := form.FromMap(map[string]json.RawMessage{"a": raw(t, "old-a")})
-	p := form.Patch{
-		Set: map[string]json.RawMessage{
-			"zeta":  raw(t, "1"),
-			"alpha": raw(t, "2"),
-			"a":     raw(t, "new-a"),
-		},
-		Remove: []string{"omega"},
-	}
+	p := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+		"zeta":  raw(t, "1"),
+		"alpha": raw(t, "2"),
+		"a":     raw(t, "new-a"),
+	}, []string{"omega"})
 	es := form.PatchEntries(p, prev)
 	keys := make([]string, len(es))
 	for i, e := range es {
@@ -286,3 +276,12 @@ func TestLint_CleanBody(t *testing.T) {
 func writeFile(path, body string) error {
 	return os.WriteFile(path, []byte(body), 0o600)
 }
+
+// mustEntry is the value a patch sets at key.
+func mustEntry(p form.Patch, key string) []byte {
+	e, ok := p.Entry(key)
+	if !ok {
+		return nil
+	}
+	return e.New
+}

api/form/incantation_test.go

@@ -40,14 +40,14 @@ func TestStudyIncantationReadsEveryEvent(t *testing.T) {
 	if got.OnStudy != "watch it" || got.OnUpdate != "it moved" || got.OnDrop != "look away" {
 		t.Fatalf("all three events should carry their phrase, got %+v", got)
 	}
-	if got.IsIdentity() {
+	if got.IsEmpty() {
 		t.Fatal("a populated incantation reports itself empty")
 	}
 }
 
 func TestStudyIncantationAbsentIsSilentAndEmpty(t *testing.T) {
 	out := captureWarnings(t, func() {
-		if got := ReadStudyIncantation(Snapshot{}); !got.IsIdentity() {
+		if got := ReadStudyIncantation(Snapshot{}); !got.IsEmpty() {
 			t.Fatalf("no key should read as no incantation, got %+v", got)
 		}
 	})
@@ -85,7 +85,7 @@ func TestStudyIncantationWrongShapeIsRefusedWholesale(t *testing.T) {
 			out := captureWarnings(t, func() {
 				got = ReadStudyIncantation(boardWith(t, StudyIncantationKey, tc.raw))
 			})
-			if !got.IsIdentity() {
+			if !got.IsEmpty() {
 				t.Fatalf("a %s must not parse as an incantation: %+v", tc.name, got)
 			}
 			if !strings.Contains(out, tc.kind) {
@@ -104,7 +104,7 @@ func TestStudyIncantationNamesUnknownKeys(t *testing.T) {
 	board := boardWith(t, StudyIncantationKey, `{"onstudied":"watch it"}`)
 	var got StudyIncantation
 	out := captureWarnings(t, func() { got = ReadStudyIncantation(board) })
-	if !got.IsIdentity() {
+	if !got.IsEmpty() {
 		t.Fatalf("an unknown field must not become a phrase: %+v", got)
 	}
 	if !strings.Contains(out, "onstudied") || !strings.Contains(out, "onstudy") {
@@ -125,7 +125,7 @@ func TestForkIncantationWrongShapeIsRefused(t *testing.T) {
 	out := captureWarnings(t, func() {
 		got = ReadForkIncantation(boardWith(t, ForkIncantationKey, `["a","b"]`))
 	})
-	if !got.IsIdentity() {
+	if !got.IsEmpty() {
 		t.Fatalf("an array must not parse: %+v", got)
 	}
 	if !strings.Contains(out, "array") {
@@ -137,7 +137,7 @@ func TestForkIncantationWrongShapeIsRefused(t *testing.T) {
 // says less than nothing: it tells the model there was something to say.
 func TestIncantationTrimsAndDropsBlank(t *testing.T) {
 	s := ReadStudyIncantation(boardWith(t, StudyIncantationKey, `{"onstudy":"   "}`))
-	if !s.IsIdentity() {
+	if !s.IsEmpty() {
 		t.Fatalf("a blank phrase must be no phrase: %+v", s)
 	}
 	f := ReadForkIncantation(boardWith(t, ForkIncantationKey, `"  branched  "`))

api/form/lint_catalog_test.go

@@ -30,16 +30,14 @@ func TestDefaultTemplates_LintClean(t *testing.T) {
 	prev := form.FromMap(map[string]json.RawMessage{
 		"model": rawString("claude-sonnet-4-6"),
 	})
-	patch := form.Patch{
-		Set: map[string]json.RawMessage{
-			"cwd":          rawString("/home/figaro/dev"),
-			"datetime":     rawString("Wednesday, April 29, 2026, 10AM EDT"),
-			"model":        rawString("claude-opus-4-6"),
-			"root":         rawString("/home/figaro/dev"),
-			"truncation":   rawString("File foo.go truncated to 2000 lines"),
-			"token_budget": rawString("80%"),
-		},
-	}
+	patch := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+		"cwd":          rawString("/home/figaro/dev"),
+		"datetime":     rawString("Wednesday, April 29, 2026, 10AM EDT"),
+		"model":        rawString("claude-opus-4-6"),
+		"root":         rawString("/home/figaro/dev"),
+		"truncation":   rawString("File foo.go truncated to 2000 lines"),
+		"token_budget": rawString("80%"),
+	}, nil)
 
 	rendered, err := form.Render(patch, prev, tmpls)
 	require.NoError(t, err)
@@ -59,7 +57,11 @@ func TestDefaultTemplates_LintClean(t *testing.T) {
 	for _, r := range rendered {
 		rkeys[r.Key] = true
 	}
-	for k := range patch.Set {
+	for _, ent := range patch.Entries() {
+		if ent.IsRemoval() {
+			continue
+		}
+		k := ent.Key
 		assert.True(t, rkeys[k], "expected default template for %q to produce output", k)
 	}
 }
@@ -78,14 +80,12 @@ func TestDefaultTemplates_AllBodiesAreFactual(t *testing.T) {
 		return b
 	}
 
-	patch := form.Patch{
-		Set: map[string]json.RawMessage{
-			"cwd":      rawString("/home/figaro"),
-			"datetime": rawString("Wednesday, April 29, 2026, 10AM EDT"),
-			"model":    rawString("claude-opus-4-6"),
-			"root":     rawString("/home/figaro"),
-		},
-	}
+	patch := form.Build(form.Snapshot{}, map[string]json.RawMessage{
+		"cwd":      rawString("/home/figaro"),
+		"datetime": rawString("Wednesday, April 29, 2026, 10AM EDT"),
+		"model":    rawString("claude-opus-4-6"),
+		"root":     rawString("/home/figaro"),
+	}, nil)
 	rendered, err := form.Render(patch, form.Snapshot{}, tmpls)
 	require.NoError(t, err)
 

api/form/state_test.go

@@ -27,10 +27,10 @@ func TestState_ApplyAndSave_RoundTrip(t *testing.T) {
 	s, err := form.Open(path)
 	require.NoError(t, err)
 
-	patch := form.PatchCreates(map[string]json.RawMessage{
+	patch := form.Build(form.Snapshot{}, map[string]json.RawMessage{
 		"system.credo": json.RawMessage(`"you are figaro"`),
 		"cwd":          json.RawMessage(`"/home/figaro"`),
-	})
+	}, nil)
 	post := s.Apply(patch)
 	assert.Equal(t, json.RawMessage(`"/home/figaro"`), val(post, "cwd"))
 
@@ -50,10 +50,10 @@ func TestState_Snapshot_ReturnsClone(t *testing.T) {
 	require.NoError(t, err)
 	defer s.Close()
 
-	s.Apply(form.PatchCreates(map[string]json.RawMessage{"k": json.RawMessage(`"v"`)}))
+	s.Apply(form.Build(form.Snapshot{}, map[string]json.RawMessage{"k": json.RawMessage(`"v"`)}, nil))
 	snap1 := s.Snapshot()
 	// Derive a mutated snapshot from the clone.
-	snap1 = snap1.Apply(form.PatchCreates(map[string]json.RawMessage{"k": json.RawMessage(`"mutated"`)}))
+	snap1 = snap1.Apply(form.Build(form.Snapshot{}, map[string]json.RawMessage{"k": json.RawMessage(`"mutated"`)}, nil))
 	_ = snap1
 
 	snap2 := s.Snapshot()
@@ -91,14 +91,14 @@ func TestState_RemovePatch(t *testing.T) {
 	s, err := form.Open(path)
 	require.NoError(t, err)
 
-	s.Apply(form.PatchCreates(map[string]json.RawMessage{"k": json.RawMessage(`"v"`)}))
+	s.Apply(form.Build(form.Snapshot{}, map[string]json.RawMessage{"k": json.RawMessage(`"v"`)}, nil))
 	require.NoError(t, s.Save())
 	require.NoError(t, s.Close())
 
 	s2, err := form.Open(path)
 	require.NoError(t, err)
 	defer s2.Close()
-	s2.Apply(form.PatchBuild(Snapshot{}, nil, []string{"k"}))
+	s2.Apply(form.Build(form.Snapshot{}, nil, []string{"k"}))
 	snap := s2.Snapshot()
 	assert.False(t, snap.Has("k"))
 	require.NoError(t, s2.Save())
@@ -110,7 +110,7 @@ func TestState_Close_FlushesPending(t *testing.T) {
 	s, err := form.Open(path)
 	require.NoError(t, err)
 
-	s.Apply(form.PatchCreates(map[string]json.RawMessage{"k": json.RawMessage(`"v"`)}))
+	s.Apply(form.Build(form.Snapshot{}, map[string]json.RawMessage{"k": json.RawMessage(`"v"`)}, nil))
 	require.NoError(t, s.Close()) // should flush
 
 	data, err := os.ReadFile(path)

api/form/testhelp_test.go

@@ -0,0 +1,10 @@
+package form
+
+// mustEntry is the value a patch sets at key, for tests that assert on one.
+func mustEntry(p Patch, key string) []byte {
+	e, ok := p.Entry(key)
+	if !ok {
+		return nil
+	}
+	return e.New
+}