Show the answering model in the inspector and mark model switches on the strip (#8)

TranscriptMessage now carries providerID/modelID (it was already on OpenCode's
own message, just never copied over), so the inspector shows a Model line for
assistant turns and steps, not only branch headers. The Model lane's turn rule
also thickens to a heavier glyph at the turn where the model actually
switched, since colour there is already spoken for by kind (text/reasoning).

Also fixes two `y`-copy papercuts found while testing this: a branch/separator
row silently did nothing instead of saying there's nothing to copy, and OSC 52
"success" (which has no ack from the terminal) is no longer trusted alone —
copyText always writes the local fallback file too, so a paste that silently
didn't land still has one reliable place to read it from.

Author: navbytes

CHANGELOG.md

@@ -1,5 +1,27 @@
 # Changelog
 
+## 0.2.5
+
+- **The model that answered is no longer invisible.** `TranscriptMessage` now carries the
+  assistant's `providerID`/`modelID` (it was already on OpenCode's own message, just never
+  copied over), so the inspector shows a `Model` line for assistant turns and steps, not only
+  for branch headers. The Model lane's turn rule also thickens (`┃` instead of `│`) at the turn
+  where the answering model actually switches — colour there was already spoken for by
+  kind (text/reasoning), so a switch gets a shape change on the rule rather than a competing
+  colour.
+
+- **Fixed:** `y` silently did nothing on a `⎇` branch row or a separator — there's no message
+  there to copy, but it gave no feedback either, which read as "copy is broken" rather than
+  "nothing here to copy." It now notifies either way.
+
+- **Fixed: `y` on a large payload could report success while the terminal quietly dropped it.**
+  OSC 52 (the escape-sequence clipboard `y` used) has no ack from the terminal — a `true` from
+  `@opentui` only means the sequence was written, not that the terminal actually applied it, and
+  some terminals silently truncate or drop payloads past their own size cap. `copyText` now
+  always writes `.opencode/context-tree/last-copy.txt` too, clipboard hit or not, so a paste
+  that silently didn't land still has one reliable place to read it from — the toast says so
+  when the target was the clipboard.
+
 ## 0.2.4 — 2026-09-04
 
 - Consumers (`s`) counts the **system prompt**. It walked the transcript only, so its total

DESIGN.md

@@ -504,6 +504,15 @@ records as user messages, and can use the headless `/ctree` commands.
 > cells would merge and the pills would stop being countable events. When the layout overflows,
 > a one-line overview track under the lanes shows the window's position and red ticks at failed
 > tool calls, so global orientation survives without giving up pill fidelity.
+>
+> **Model switches (0.2.5).** Colour on the Model lane is categorical by *kind* (text vs.
+> reasoning), not by which model answered — recoloring per model would compete with that and
+> with the error/warning colours other lanes already use. So a mid-session model change (an
+> explicit switch, not a branch's fixed `--model`) is marked structurally instead: the turn
+> rule on the Model lane thickens to `┃` at the turn where the answering model differs from the
+> last turn that had one. The inspector's `Model` line (now populated for assistant turns and
+> steps, from the message's own `providerID`/`modelID`) is the way to confirm which model that
+> actually was.
 
 **On the DSH comparison.** The three-lane split is ours. DSH's own `ui-trajectory` README
 describes a *single* combined Overview ("A fixed Overview above the ledger projects real record

src/core/lanes.ts

@@ -77,6 +77,8 @@ export type LaneEvent = {
   durationMs?: number
   error?: boolean
   tokens: number
+  /** `providerID/modelID` of the assistant message this event belongs to (model-lane events only). */
+  model?: string
 }
 
 /** One terminal cell of one lane. */
@@ -121,7 +123,8 @@ function partEvent(message: TranscriptMessage, part: StepPart, turn: number): La
   }
   if (part.type === "tool")
     return { ...base, lane: "tools", kind: "tool", error: part.state?.status === "error", tokens: estimateTokens(part.state?.output ?? "") + estimateTokens(JSON.stringify(part.state?.input ?? "")) }
-  return { ...base, lane: "model", kind: part.type === "reasoning" ? "reasoning" : "text", tokens: estimateTokens(part.text ?? "") }
+  const model = message.model ? `${message.model.providerID}/${message.model.modelID}` : undefined
+  return { ...base, lane: "model", kind: part.type === "reasoning" ? "reasoning" : "text", tokens: estimateTokens(part.text ?? ""), model }
 }
 
 /**
@@ -205,6 +208,10 @@ export type EventLayout = {
   empty: Record<LaneEvent["lane"], boolean>
   /** cells carrying a turn rule, drawn across every lane */
   rules: number[]
+  /** subset of `rules` where the Model lane's answering model differs from the previous turn
+   *  that had one — the strip's only cue that a switch happened (DESIGN.md §7.1 keeps colour
+   *  categorical by lane, not per-model, so this rides the existing turn-rule machinery). */
+  modelChanges: number[]
 }
 
 /**
@@ -215,12 +222,24 @@ export type EventLayout = {
 export function layoutEventStrip(transcript: Transcript, mode: LaneMode, filter: Filter = "all"): EventLayout {
   const events = eventsOf(transcript, filter)
   const widths = mode === "duration" ? durationWidths(events, events.length * DURATION_CELLS) : events.map(() => 1)
+  // one representative model per turn (its first Model-lane event that has one), so a turn with
+  // no text/reasoning (tool-only, or a filter that hid it) carries no opinion either way
+  const turnModel = new Map<number, string>()
+  for (const e of events) if (e.lane === "model" && e.model && !turnModel.has(e.turn)) turnModel.set(e.turn, e.model)
+  let lastModel = turnModel.get(events[0]?.turn ?? -1)
   const spans: { start: number; end: number }[] = []
   const rules: number[] = []
+  const modelChanges: number[] = []
   let cursor = 0
   events.forEach((_, i) => {
     const boundary = isTurnBoundary(events, i)
-    if (boundary) rules.push(cursor + 1) // centred in the wider gap it opens
+    if (boundary) {
+      const cell = cursor + 1
+      rules.push(cell) // centred in the wider gap it opens
+      const model = turnModel.get(events[i]!.turn)
+      if (model && lastModel && model !== lastModel) modelChanges.push(cell)
+      if (model) lastModel = model
+    }
     const start = cursor + (i === 0 ? 0 : boundary ? TURN_RULE_GAP : 1)
     cursor = start + (widths[i] ?? 1)
     spans.push({ start, end: cursor })
@@ -232,7 +251,7 @@ export function layoutEventStrip(transcript: Transcript, mode: LaneMode, filter:
     for (let c = spans[i]!.start; c < spans[i]!.end; c++) lanes[e.lane][c] = cell
   })
   const has = (lane: LaneEvent["lane"]) => !events.some((e) => e.lane === lane)
-  return { events, spans, totalWidth: cursor, lanes, empty: { input: has("input"), model: has("model"), tools: has("tools") }, rules }
+  return { events, spans, totalWidth: cursor, lanes, empty: { input: has("input"), model: has("model"), tools: has("tools") }, rules, modelChanges }
 }
 
 /**

src/core/transcript.ts

@@ -31,6 +31,9 @@ export type TranscriptMessage = {
   /** OpenCode-native compaction summary marker (not the ctree "jump summary", which is a
    *  regular user message tagged via `metadata.ctree.kind === "summary"` instead). */
   summary?: boolean
+  /** The model that answered (assistant messages only) — for the inspector and the strip's
+   *  model-change marker. */
+  model?: { providerID: string; modelID: string }
   parts: StepPart[]
 }
 

src/tui/actions.ts

@@ -713,14 +713,17 @@ export const BRANCH_DIALOG = { title: "Branch here → new OpenCode session", pl
 export const COPY_HINT = ".opencode/context-tree/last-copy.txt"
 
 /** `y` copy: the terminal's own clipboard through @opentui's OSC 52 (works over ssh/tmux when
- *  the terminal allows it), falling back to `COPY_HINT`. Throws if that file cannot be written. */
+ *  the terminal allows it) — but OSC 52 has no ack from the terminal, so a `true` here only
+ *  means the escape sequence was written, not that the terminal actually applied it (some
+ *  silently drop or truncate large payloads with no visible sign). `COPY_HINT` is therefore
+ *  always written too, whether or not OSC 52 reports success, so there's one place that's
+ *  reliably the last thing you copied. Throws if that file cannot be written. */
 export function copyText(api: TuiPluginApi, text: string, directory: string): { target: "clipboard" | "file"; hint: string } {
-  const renderer = api.renderer as unknown as { copyToClipboardOSC52?: (text: string) => boolean } | undefined
-  // an empty selection must never wipe the user's clipboard; it still lands in the file
-  if (text && renderer?.copyToClipboardOSC52?.(text)) return { target: "clipboard", hint: "clipboard" }
   const file = path.join(directory, COPY_HINT)
   fs.mkdirSync(path.dirname(file), { recursive: true })
   fs.writeFileSync(file, text)
+  const renderer = api.renderer as unknown as { copyToClipboardOSC52?: (text: string) => boolean } | undefined
+  if (text && renderer?.copyToClipboardOSC52?.(text)) return { target: "clipboard", hint: "clipboard" }
   return { target: "file", hint: COPY_HINT }
 }
 

src/tui/route.tsx

@@ -14,7 +14,7 @@ import { buildSpineMap, buildTreeView, currentChainOf, formatPromptAt, promptAtR
 import { ContextGauge } from "./gauge.js"
 import type { Transcript } from "../core/transcript.js"
 import type { JournalStore } from "../shared/store.js"
-import { applyCrop, branchLabel, BRANCH_DIALOG, clip as clipTo, copyText, createNamedBranch, describeTail, executeJump, executeUndo, jumpDialogOptions, jumpDialogTitle, mergeBranch, mergeDialogOptions, mergeDialogTitle, mergePickerFigures, MERGE_TRUST, setLabel, UNDO_KEY, type ActionContext, type MergeMode, type SummaryChoice } from "./actions.js"
+import { applyCrop, branchLabel, BRANCH_DIALOG, clip as clipTo, COPY_HINT, copyText, createNamedBranch, describeTail, executeJump, executeUndo, jumpDialogOptions, jumpDialogTitle, mergeBranch, mergeDialogOptions, mergeDialogTitle, mergePickerFigures, MERGE_TRUST, setLabel, UNDO_KEY, type ActionContext, type MergeMode, type SummaryChoice } from "./actions.js"
 import { decisionSummary, exportDecisions, renderDecision } from "../core/decision.js"
 import { laneLabel, laneSuffix, layoutEventStrip, overviewTrack, stripIndexFor, windowFor, LANE_CHROME, type LaneMode, type StripCell } from "../core/lanes.js"
 import { bar, consumers, type Consumer, type ConsumerEntry } from "../core/consumers.js"
@@ -634,16 +634,20 @@ export function TreeRoute(props: TreeRouteProps) {
     const start = laneOffset()
     const w = laneWidth()
     const rules = new Set(layout().rules)
+    const modelChanges = new Set(layout().modelChanges)
     const runs: { text: string; fg: unknown; bg: unknown }[] = []
     for (let c = 0; c < w; c++) {
       const cell = layout().lanes[lane][start + c] ?? null
       const sel = cell !== null && cur.has(cell.eventIndex)
-      const color = cell === null ? t.textMuted : cellColor(cell)
+      const changedHere = lane === "model" && modelChanges.has(start + c)
+      const color = cell === null ? (changedHere ? t.primary : t.textMuted) : cellColor(cell)
       const fg = sel ? t.background : color
       const bg = sel ? color : undefined
       // a turn boundary is a rule across all three lanes, the way DSH marks turns on its
-      // Overview — it never lands on a pill, the gap that holds it is opened for it
-      const glyph = cell?.glyph ?? (rules.has(start + c) ? "│" : " ")
+      // Overview — it never lands on a pill, the gap that holds it is opened for it. On the
+      // Model lane that rule thickens where the answering model actually switched, since colour
+      // there is already spoken for by kind (text/reasoning), not identity.
+      const glyph = cell?.glyph ?? (changedHere ? "┃" : rules.has(start + c) ? "│" : " ")
       const last = runs[runs.length - 1]
       if (last && last.fg === fg && last.bg === bg) last.text += glyph
       else runs.push({ text: glyph, fg, bg })
@@ -741,6 +745,7 @@ export function TreeRoute(props: TreeRouteProps) {
       if (row.label) kv("Label", row.label)
       kv("Tokens", `~${formatK(row.tokens)}`)
       kv("At", msg ? new Date(msg.time.created).toISOString().slice(11, 19) : "?")
+      if (msg?.model) kv("Model", `${msg.model.providerID}/${msg.model.modelID}`)
       if (!row.inContext) muted("not in this branch's context")
       block("Text", text)
       return out
@@ -749,6 +754,7 @@ export function TreeRoute(props: TreeRouteProps) {
     const stepNo = msg ? msg.parts.filter((p) => p.type === "tool" || p.type === "text").findIndex((p) => p.id === row.partID) + 1 : 0
     head(`${row.glyph} ${part?.type === "tool" ? part.tool : row.glyph === "◇" ? "compaction" : "assistant"} · T${turn?.kind === "turn" ? turn.turn : "?"} · step ${stepNo}`)
     kv("Hierarchy", `T${turn?.kind === "turn" ? turn.turn : "?"} › assistant › step ${stepNo}`)
+    if (msg?.model) kv("Model", `${msg.model.providerID}/${msg.model.modelID}`)
     if (!row.inContext) muted("not in this branch's context")
     if (row.tokenFields) {
       const tf = row.tokenFields
@@ -859,6 +865,11 @@ export function TreeRoute(props: TreeRouteProps) {
     notify(picks.length ? `marked ${picks.length} unprotected ${c.source} result${picks.length === 1 ? "" : "s"} — ⏎ to apply` : `every ${c.source} result is protected; mark with space (twice) to override`)
   }
 
+  /** OSC 52 clipboard "success" has no ack from the terminal, so `copyText` always writes
+   *  `COPY_HINT` too — surface it even on a reported clipboard hit, since that's the only
+   *  place a large paste that silently didn't land is still reliably sitting. */
+  const copyNotice = (length: number, hint: string) => `copied ${length} chars → ${hint}${hint === "clipboard" ? ` (paste empty? it's also at ${COPY_HINT})` : ""}`
+
   function copySelected() {
     // in the consumers panel `y` copies the selected entry — the only way to read a system
     // part in full, since it is not a message and has no row of its own
@@ -867,17 +878,24 @@ export function TreeRoute(props: TreeRouteProps) {
       const idx = line?.bucket.kind === "system" ? line.entry?.systemIndex : undefined
       const part = idx === undefined ? undefined : systemParts()?.[idx]
       const text = part?.text ?? line?.entry?.preview ?? ""
-      if (!text) return
+      if (!text) {
+        notify("nothing to copy here")
+        return
+      }
       try {
         const { hint } = copyText(api, text, directory)
-        notify(`copied ${text.length} chars → ${hint}`)
+        notify(copyNotice(text.length, hint))
       } catch (e) {
         notify(`copy failed: ${e instanceof Error ? e.message : String(e)}`)
       }
       return
     }
     const row = current()
-    if (!row || row.kind === "branch" || row.kind === "separator") return
+    if (!row) return
+    if (row.kind === "branch" || row.kind === "separator") {
+      notify(row.kind === "branch" ? "nothing to copy on a branch row — pick a turn or step" : "nothing to copy on a separator")
+      return
+    }
     const tr = row.sessionID === sessionID ? live() : others()[row.sessionID]
     const msg = tr?.messages.find((m) => m.id === row.messageID)
     const text = row.kind === "step" ? String(msg?.parts.find((p) => p.id === row.partID)?.state?.output ?? msg?.parts.find((p) => p.id === row.partID)?.text ?? "") : (msg?.parts.map((p) => p.text ?? "").join("\n") ?? "")

src/tui/transcripts.ts

@@ -5,7 +5,7 @@
 import type { TuiPluginApi } from "@opencode-ai/plugin/tui"
 import type { StepPart, Transcript, TranscriptMessage } from "../core/transcript.js"
 
-type AnyMessage = { id: string; role: string; time: { created: number; completed?: number }; tokens?: TranscriptMessage["tokens"]; summary?: unknown }
+type AnyMessage = { id: string; role: string; time: { created: number; completed?: number }; tokens?: TranscriptMessage["tokens"]; summary?: unknown; providerID?: string; modelID?: string }
 type AnyPart = { id: string; type: string; text?: string; tool?: string; callID?: string; state?: StepPart["state"]; time?: StepPart["time"]; metadata?: Record<string, unknown> }
 
 export function toStepPart(p: AnyPart): StepPart {
@@ -19,6 +19,7 @@ export function toTranscriptMessage(m: AnyMessage, parts: readonly AnyPart[]): T
     time: m.time,
     tokens: m.tokens,
     summary: m.role === "assistant" && m.summary === true ? true : undefined,
+    model: m.role === "assistant" && m.providerID && m.modelID ? { providerID: m.providerID, modelID: m.modelID } : undefined,
     parts: parts.map(toStepPart),
   }
 }

test/fixtures/tree.ts

@@ -13,7 +13,10 @@ const tick = () => (t += 1000)
 export function user(id: string, text: string): TranscriptMessage {
   return { id, role: "user", time: { created: tick() }, parts: [{ id: `${id}-p0`, type: "text", text }] }
 }
-export function assistant(id: string, opts: { text?: string; think?: { text?: string; ms?: number }; tool?: { name: string; input: unknown; output: string; ms?: number }; input?: number; output?: number }): TranscriptMessage {
+export function assistant(
+  id: string,
+  opts: { text?: string; think?: { text?: string; ms?: number }; tool?: { name: string; input: unknown; output: string; ms?: number }; input?: number; output?: number; model?: { providerID: string; modelID: string } },
+): TranscriptMessage {
   const parts: TranscriptMessage["parts"] = [{ id: `${id}-ss`, type: "step-start" }]
   if (opts.think) {
     const start = tick()
@@ -25,7 +28,7 @@ export function assistant(id: string, opts: { text?: string; think?: { text?: st
   }
   if (opts.text) parts.push({ id: `${id}-text`, type: "text", text: opts.text })
   parts.push({ id: `${id}-sf`, type: "step-finish" })
-  return { id, role: "assistant", time: { created: tick() }, tokens: { input: opts.input ?? 1000, output: opts.output ?? 50, reasoning: 0, cache: { read: 0, write: 0 } }, parts }
+  return { id, role: "assistant", time: { created: tick() }, tokens: { input: opts.input ?? 1000, output: opts.output ?? 50, reasoning: 0, cache: { read: 0, write: 0 } }, model: opts.model, parts }
 }
 
 /** Copy a prefix the way `session.fork` does: same content, fresh IDs. */

test/lanes.test.ts

@@ -108,6 +108,42 @@ describe("event strip", () => {
     }
   })
 
+  test("modelChanges marks the boundary where the answering model actually switches", () => {
+    const sonnet = { providerID: "anthropic", modelID: "claude-sonnet-5" }
+    const opus = { providerID: "anthropic", modelID: "claude-opus-5" }
+    const three = T([
+      user("u1", "a"),
+      assistant("a1", { text: "one", model: sonnet }),
+      user("u2", "b"),
+      assistant("a2", { text: "two", model: sonnet }), // same model: no mark
+      user("u3", "c"),
+      assistant("a3", { text: "three", model: opus }), // switched: mark
+    ])
+    const l = layoutEventStrip(three, "turns")
+    expect(l.rules.length).toBe(2)
+    expect(l.modelChanges).toEqual([l.rules[1]])
+  })
+
+  test("no model data at all: modelChanges stays empty, never guesses", () => {
+    const two = T([user("u1", "a"), assistant("a1", { text: "one" }), user("u2", "b"), assistant("a2", { text: "two" })])
+    expect(layoutEventStrip(two, "turns").modelChanges).toEqual([])
+  })
+
+  test("a tool-only turn between two models carries no opinion: the switch still shows on the next text turn", () => {
+    const sonnet = { providerID: "anthropic", modelID: "claude-sonnet-5" }
+    const opus = { providerID: "anthropic", modelID: "claude-opus-5" }
+    const three = T([
+      user("u1", "a"),
+      assistant("a1", { text: "one", model: sonnet }),
+      user("u2", "b"),
+      assistant("a2", { tool: { name: "bash", input: { command: "ls" }, output: "out" } }), // no text/model
+      user("u3", "c"),
+      assistant("a3", { text: "three", model: opus }),
+    ])
+    const l = layoutEventStrip(three, "turns")
+    expect(l.modelChanges).toEqual([l.rules[1]])
+  })
+
   test("duration mode: widths follow durations, untimed events keep one cell", () => {
     const slow = assistant("a1", { tool: { name: "bash", input: { command: "slow" }, output: "x", ms: 8000 } })
     const fast = assistant("a2", { tool: { name: "bash", input: { command: "fast" }, output: "x", ms: 1000 } })