Add one-click chat model switching and saved rotations

docs/changes/unreleased/1900-chat-model-rotation.md

@@ -0,0 +1,15 @@
+---
+kind: added
+title: switch between saved chat models directly beside the composer
+pr: 1900
+surface: [chat]
+invalidates:
+  - >-
+    Switching chat models required opening the model picker or typing a model
+    command. A saved rotation now adds an exchange control beside the chat model;
+    a click or f3 advances it without disturbing the draft.
+  - >-
+    Settings could select one chat model but could not hold a quick-switch list.
+    Models now has an ordered multi-selection row; entries persist across launches
+    and never change task models.
+---

docs/design/icons/DESIGN.md

@@ -298,3 +298,10 @@ own page, a run held at its spend gate drew the banned `⏸`, and the fold mark
 `GTeamDot` marks a team identity in the Teams sidebar: `●` in the plain tier,
 `nf-fa-circle` in the Nerd Font tier, and `o` in ASCII. All teams uses white ink.
 The navigation tree separates this circle from work-state dots by position.
+
+### Chat model exchange
+
+The quick-switch control beside the chat model reuses `GActionTransfer`: an
+exchange between model choices. It retains the vocabulary's plain `⇄`, Nerd Font
+`nf-fa-exchange`, and ASCII `&` spellings. The padded control has its own pointer
+span, separate from the model name that opens the catalog.

internal/config/derivation_test.go

@@ -115,12 +115,13 @@ func TestEveryRowIsGroupedNamedAndReadable(t *testing.T) {
 // wave apiece — so what is named here is the thing the reader touches, not the
 // spelling of the key.
 var settingReaders = map[string]string{
-	KeyWork:           "workMode",
-	KeyIcons:          "iconMode",
-	KeyDailyBudget:    "DailyBudgetUSD",
-	KeyPlanConsent:    "PlanConsentUSD",
-	KeyDocumentEngine: "DocumentEngine",
-	KeyVisionModel:    "VisionModel",
+	KeyChatModelRotation: "ChatModelRotationAt",
+	KeyWork:              "workMode",
+	KeyIcons:             "iconMode",
+	KeyDailyBudget:       "DailyBudgetUSD",
+	KeyPlanConsent:       "PlanConsentUSD",
+	KeyDocumentEngine:    "DocumentEngine",
+	KeyVisionModel:       "VisionModel",
 	// The model-name row names the one resolver every door turns it into a
 	// name through: the leaf loops' doors hand [AssistedByModelAt]'s answer to
 	// the attribution line.

internal/config/modelrotation.go

@@ -0,0 +1,17 @@
+package config
+
+import "strings"
+
+// KeyChatModelRotation holds an ordered preference, separate from automatic fallbacks.
+const KeyChatModelRotation = "models.quick_switch"
+
+// ChatModelRotationAt reads the saved order without introducing catalog defaults.
+func ChatModelRotationAt(dir string) []string {
+	raw, _ := persistedString(dir, KeyChatModelRotation)
+	return ParseModelFallbacks(raw)
+}
+
+// WriteChatModelRotation uses the profile writer so unrelated preferences survive.
+func WriteChatModelRotation(dir, raw string) error {
+	return writeProfileValue(dir, KeyChatModelRotation, strings.Join(ParseModelFallbacks(raw), ", "))
+}

internal/config/modelrotation_test.go

@@ -0,0 +1,33 @@
+package config
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestChatModelRotationPersistsOrderAndPreservesOtherSettings(t *testing.T) {
+	dir := t.TempDir()
+	if err := WriteChatModel(dir, "vendor/current"); err != nil {
+		t.Fatal(err)
+	}
+	registry := NewSettings(SettingsOptions{ProfileDir: dir})
+	row, ok := registry.Row(KeyChatModelRotation)
+	if !ok {
+		t.Fatal("missing rotation setting")
+	}
+	if err := row.Apply("vendor/b, vendor/a, vendor/b, , vendor/c"); err != nil {
+		t.Fatal(err)
+	}
+	if got := ChatModelRotationAt(dir); !reflect.DeepEqual(got, []string{"vendor/b", "vendor/a", "vendor/c"}) {
+		t.Fatalf("order = %v", got)
+	}
+	if got := ChatModelAt(dir); got != "vendor/current" {
+		t.Fatalf("setting rotation changed chat: %s", got)
+	}
+	if err := row.Apply(""); err != nil {
+		t.Fatal(err)
+	}
+	if got := ChatModelRotationAt(dir); len(got) != 0 {
+		t.Fatalf("cleared list = %v", got)
+	}
+}

internal/config/settings.go

@@ -2420,6 +2420,13 @@ func (s *Settings) build() []Setting {
 			read:  func() string { return LivePinsAt(dir) },
 			write: func(raw string) error { return writeModelRoles(dir, raw) },
 		},
+		Setting{
+			Key: KeyChatModelRotation, Category: CategoryModels, Kind: SettingText,
+			Label: "quick switch models", EmptyLabel: "choose models",
+			Hint:  "your chat model rotation, in click order. Choose models in settings, or write comma-separated model ids. The switch beside your chat model advances through this list; it does not change task models.",
+			read:  func() string { return strings.Join(ChatModelRotationAt(dir), ", ") },
+			write: func(raw string) error { return WriteChatModelRotation(dir, raw) },
+		},
 		Setting{
 			Key: KeyModelFallbacks, Category: CategoryModels, Kind: SettingText,
 			Label: "fallback models", EmptyLabel: "nearest in the catalog",

internal/config/testdata/profile-keys.ledger

@@ -57,6 +57,7 @@ models.crew.source
 models.crew.task_cap
 models.fallbacks
 models.pool.public_key
+models.quick_switch
 models.roles
 models.tiers.high
 models.tiers.low

internal/manual/chat/quick-switch-models.md

@@ -0,0 +1,24 @@
+# Quick switch chat models
+
+## How do I switch between my usual chat models without opening the model picker
+
+Click the exchange mark beside the chat model above your message box, or press
+**f3**. It advances through **quick switch models** in Settings → Models, in the order you chose. The model name changes immediately; your draft,
+its cursor and your conversation stay in place. Task models do not change.
+For three or more saved models, the position (for example `1/3`) appears beside
+the mark. The mark follows the Display icon setting: plain exchange arrows, a Nerd Font
+exchange icon, or `&` in ASCII. Hover names the next model and the f3 shortcut.
+
+With fewer than two saved models the mark is hidden; f3 opens **quick switch
+models** in settings. Enter opens the catalog there. Type to filter, then press enter to
+add or remove a model. The **Click order:** line shows the saved rotation.
+Selections save immediately; esc finishes choosing. Removing a model and adding
+it again moves it to the end. Choosing the rotation does not change the model
+of the current chat. The list survives restarting codeaf.
+
+A model selected outside the rotation is allowed: the next switch returns to
+the first saved model. A switch uses the same live model change as `/model`;
+when a response is running, it can redirect the next request in that response.
+It does not promise to leave an in-flight response on its original model.
+The model name itself still opens the full picker. The quick-switch control
+belongs to a chat, not to home, settings, or a task room.

internal/tui3/app.go

@@ -1353,6 +1353,9 @@ type app struct {
 	// now (foot.go's [app.seamIdentity]). modelSpan above is the room chip's
 	// door on the status row; the two are never both drawn.
 	seamModelSpan hudSpan
+	// The rotation is cached at launch and settings saves; rendering never reads disk.
+	modelRotation      []string
+	seamModelCycleSpan hudSpan
 	// seamProjectSpan is the current workspace path at the rule’s right edge.
 	seamProjectSpan hudSpan
 	// seamEffortSpan is the thinking rung's own columns on that same line, drawn
@@ -3011,6 +3014,7 @@ func newApp(ctx context.Context, opts Options) *app {
 		draftFile:           opts.DraftFile,
 		artifacts:           opts.ArtifactsIndex,
 		ctxWindow:           opts.ContextWindow,
+		modelRotation:       config.ChatModelRotationAt(opts.ProfileDir),
 		profileDir:          opts.ProfileDir,
 		routing:             config.RoutingAt(opts.ProfileDir),
 		oneModel:            opts.OneModel,
@@ -4721,6 +4725,9 @@ func (a *app) route(msg tea.Msg) (tea.Model, tea.Cmd) {
 			// AND THE MODEL'S NAME IS THE FOURTH, at the left end of the same
 			// legend: the conversation's model is written on the seam and pressing
 			// it opens the picker (foot.go's [app.legendModelPress]).
+			if a.legendModelCyclePress(msg.Mouse().X, msg.Mouse().Y) {
+				return a, nil
+			}
 			if a.legendModelPress(msg.Mouse().X, msg.Mouse().Y) {
 				return a, nil
 			}

internal/tui3/commands.go

@@ -1108,6 +1108,7 @@ func helpText(file string, chords chordSpelling) string {
 		// every chat; the second needs a team with a manager, and the rows say so
 		// rather than leaving a person to find out by pressing them elsewhere.
 		helpKeyRow(chords.say(trafficKey), "show or hide the right column · Tasks or Traffic"),
+		helpKeyRow(modelCycleKey, "next quick switch chat model · choose the rotation in Settings → Models"),
 		helpKeyRow(chords.say(teamManagerKey), "in a team with a manager: go to the manager"),
 		helpKeyRow(reopenTabChord, "reopen the last closed tab · when the terminal sends this distinct chord"),
 		helpKeyRow(chords.say(railHoldChord), "the task roster · ↑↓ move · ←→ tasks/traffic · enter opens · esc back"),

internal/tui3/foot.go

@@ -491,6 +491,7 @@ func (t seamTry) on(tier seamTier) bool {
 // per frame so the ladder below is only ever choosing between them.
 type seamPieces struct {
 	host, name, model, rung, gate, project string
+	exchange                               string
 	// rider is the WHOLE rider — ` (relace)`, ` (parasail · rescued)`, or a
 	// rescue's own ` · slow · trying coreweave…` — and fit is the door that
 	// answers it for a given room, or says nothing ([app.modelRiderAt]). The
@@ -523,7 +524,7 @@ func (a *app) seamPieces(width int) seamPieces {
 	// AND A PINNED LANE RIDES THE ID AS `@lane` ([app.modelWord]), which is the
 	// one place the pin is written on the chrome: the status row and the phone
 	// deck take the same word from the same function.
-	pieces := seamPieces{host: a.host, model: a.modelWord(),
+	pieces := seamPieces{host: a.host, model: a.modelWord(), exchange: a.modelCycleSuffix(),
 		project: a.seamProjectWord()}
 	// AND IN A MANAGED TEAM THE SLOT SAYS WHERE THE WORDS GO, once there are
 	// words: the empty box says it as its placeholder (teamrailpointer.go's
@@ -633,7 +634,7 @@ func (p seamPieces) lay(try seamTry, room int) (string, hudSpan, hudSpan, hudSpa
 	if try.name {
 		name = p.name
 		if try.cut {
-			rest := dotted(p.host, dotted(seamModelEffort(model+rider, rung), gate))
+			rest := dotted(p.host, dotted(seamModelEffort(model+rider, rung)+p.exchange, gate))
 			left := room - ansi.StringWidth(rest)
 			if rest != "" {
 				left -= ansi.StringWidth(legendJoin)
@@ -646,17 +647,25 @@ func (p seamPieces) lay(try seamTry, room int) (string, hudSpan, hudSpan, hudSpa
 	}
 	head := dotted(p.host, name)
 	if try.rider == riderFit && model != "" {
-		bare := dotted(head, dotted(seamModelEffort(model, rung), gate))
+		bare := dotted(head, dotted(seamModelEffort(model, rung)+p.exchange, gate))
 		if ansi.StringWidth(bare) > room {
 			return "", none, none, none, false
 		}
 		rider = p.fit(room - ansi.StringWidth(bare))
 	}
-	cluster := dotted(head, dotted(seamModelEffort(model+rider, rung), gate))
+	exchange := ""
+	if model != "" {
+		exchange = p.exchange
+	}
+	cluster := dotted(head, dotted(seamModelEffort(model+rider, rung)+exchange, gate))
 	if ansi.StringWidth(cluster) > room {
 		return "", none, none, none, false
 	}
 	named, dial, chip := seamSpans(head, model, rider, rung, gate)
+	if chip.pressable() {
+		chip.from += ansi.StringWidth(exchange)
+		chip.to += ansi.StringWidth(exchange)
+	}
 	return cluster, named, dial, chip, true
 }
 

internal/tui3/hover.go

@@ -183,6 +183,8 @@ const (
 	// where the press would do nothing, the render records no span and this
 	// answers nothing (room.go's [app.roomModelMovable]).
 	hoverStatusModel
+	// hoverModelCycle is separate from the model picker door.
+	hoverModelCycle
 	// hoverSeamProject is the project path on the message-box seam.
 	hoverSeamProject
 	// hoverEffort is the THINKING RUNG on the seam, the cell drawn immediately
@@ -663,6 +665,9 @@ func (a *app) hoverTarget(x, y int) hoverAt {
 			if !a.seamCarriesTelemetry() && a.seamProjectSpan.holds(x) {
 				return hoverAt{kind: hoverSeamProject}
 			}
+			if a.seamModelCycleSpan.holds(x) {
+				return hoverAt{kind: hoverModelCycle}
+			}
 			if a.seamModelSpan.holds(x) {
 				return hoverAt{kind: hoverStatusModel}
 			}

internal/tui3/input.go

@@ -698,6 +698,13 @@ func (a *app) key(msg tea.KeyPressMsg) tea.Cmd {
 		return cmd
 	}
 
+	// The rotation key is below every modal so it never changes a model while
+	// a person is answering a different question in a panel.
+	if msg.String() == modelCycleKey && a.at(pageNone) && !a.roomOpen() && !a.linear {
+		a.cycleChatModel()
+		return nil
+	}
+
 	// The welcome box reads two keys and gives every other one back (welcome.go):
 	// ↑/↓ walk the recent sessions, enter opens the one they picked, and
 	// anything else is the person starting work, which puts the box away for

internal/tui3/lanes_test.go

@@ -695,9 +695,14 @@ func TestEnterOnALaneInTheSettingsPickerPins(t *testing.T) {
 	}
 	// The row and the model row's tail are two readings of one fact, and both
 	// of them say so on the very next frame.
-	if !sheetHas(a, "pinned: Cloudflare") || !sheetHas(a, "· pinned: cloudflare") {
-		t.Fatalf("the panel did not re-read the pin it just wrote:\n%s",
-			strings.Join(sheetLabels(a), "\n"))
+	if !sheetHas(a, "· pinned: cloudflare") {
+		t.Fatal("the model row did not re-read the pin it just wrote")
+	}
+	// The quick-switch row adds a line above Advanced; walk to the lane row
+	// rather than assuming both readings fit in this terminal at once.
+	cursorTo(t, a, config.LaneSettingKey(talkSlot))
+	if !sheetHas(a, "pinned: Cloudflare") {
+		t.Fatalf("the lane row did not re-read the pin it just wrote:\n%s", strings.Join(sheetLabels(a), "\n"))
 	}
 	// AND THE TAIL SAYS NOTHING ABOUT THE BASE WHILE THE BASE TAKES THE CHOICE.
 	// The emptiness law: an unremarkable fact adds no words (issue #433).

internal/tui3/modelrotation.go

@@ -0,0 +1,99 @@
+package tui3
+
+import (
+	"slices"
+	"strconv"
+	"strings"
+
+	"github.com/Agent-Field/codeaf/internal/config"
+	"github.com/Agent-Field/codeaf/internal/tui2/tokens"
+)
+
+const modelCycleKey = "f3"
+
+// nextRotationModel keeps the person's order stable, including when a picker
+// selection temporarily takes the conversation outside that order.
+func (a *app) nextRotationModel() string {
+	if len(a.modelRotation) < 2 {
+		return ""
+	}
+	at := slices.Index(a.modelRotation, a.model)
+	return a.modelRotation[(at+1)%len(a.modelRotation)]
+}
+
+// modelCycleSuffix belongs only to the conversation; a task keeps its own door.
+// Fewer than two models offer no exchange, so the button is absent.
+func (a *app) modelCycleSuffix() string {
+	if !a.at(pageNone) || a.roomOpen() || a.linear || len(a.modelRotation) < 2 {
+		return ""
+	}
+	position := ""
+	if at := slices.Index(a.modelRotation, a.model); len(a.modelRotation) > 2 && at >= 0 {
+		position = strconv.Itoa(at+1) + "/" + strconv.Itoa(len(a.modelRotation)) + " "
+	}
+	return " " + position + a.icon(tokens.GActionTransfer)
+}
+
+func (a *app) legendModelCyclePress(x, y int) bool {
+	if a.copy.on || a.pick.open || a.modelCycleSuffix() == "" {
+		return false
+	}
+	mark, ok := a.chromeAt(y)
+	if !ok || mark.kind != chromeLegend || !a.seamModelCycleSpan.holds(x) {
+		return false
+	}
+	a.cycleChatModel()
+	return true
+}
+
+// toggleRotationModel writes on each explicit selection. Merely browsing never
+// changes the current chat model, and removing then adding moves an entry last.
+func (a *app) toggleRotationModel(sel *sheetSelect) {
+	model, ok := sel.choice()
+	if !ok {
+		return
+	}
+	row, ok := a.sheet.registry.Row(config.KeyChatModelRotation)
+	if !ok {
+		return
+	}
+	models := config.ChatModelRotationAt(a.profileDir)
+	if at := slices.Index(models, model); at >= 0 {
+		models = slices.Delete(models, at, at+1)
+	} else {
+		models = append(models, model)
+	}
+	meta, _ := settingMetaFor(row)
+	a.applySetting(sheetItem{row: row, meta: meta}, strings.Join(models, ", "))
+}
+
+// openModelRotationSettings takes an unconfigured switch straight to its row.
+func (a *app) openModelRotationSettings() {
+	a.openSettings()
+	a.sheet.query.reset()
+	for i, tab := range settingTabs {
+		if tab == tabProviders {
+			a.sheet.tab = i
+			break
+		}
+	}
+	a.sheet.build()
+	for i, item := range a.sheet.items {
+		if item.row.Key == config.KeyChatModelRotation {
+			a.sheet.cursor = i
+			break
+		}
+	}
+}
+
+func (a *app) cycleChatModel() {
+	if next := a.nextRotationModel(); next != "" {
+		if warning := a.nonChatWarning(next); warning != "" {
+			a.note(warning)
+			return
+		}
+		a.switchModel(next, a.windowFor(next))
+	} else {
+		a.openModelRotationSettings()
+	}
+}