chore: pi family 0.85.1 -> 0.87.1 (finishTurn, transcript contexts, typebox 1.3.27)

Mechanical fallout only; semantic deltas flagged in the wave report:
- shouldStopAfterTurn -> finishTurn ({action:'end'} wrap; loop order verified
  equivalent for Wave C stranding)
- transcript rework: seeded leading SystemMessage filtered at both
  state.messages read seams (ui-stream settleWith, pi-run slice); prompt
  and tool declarations now ride the transcript
- streamOnce sites normalizeContext() (Context -> TranscriptContext)
- AgentToolResult details / ToolCall.arguments JsonValue narrowing (casts)
- AUTH_PROVIDER_KEYS regenerated (meta added); glm-5.3-flash price pin
  follows the 0.87.1 catalog (0.15/0.5/0.05)
- vanish probe: 0/12 vs 2/6 baseline; live smoke green on PORT=3004

src/server/pi/ui-stream.ts

@@ -115,8 +115,18 @@ export function runPiTurn(spec: PiTurnSpec): PiTurnHandle {
 	// The settle seam: the record write is the agent's OWN final state
 	// (native history — signatures, usage, provider stamps all real).
 	// Copy the array: the agent may outlive this call's read.
+	// 0.87.1 (transcript rework): the Agent seeds a leading SystemMessage
+	// from initialState.systemPrompt (prompt + tool declarations) — it is
+	// synthesized per turn and must NEVER persist (the record would bloat
+	// with tool declarations AND replay would see messages[0] === system,
+	// suppressing the fresh per-turn re-seed). Our app mints no system
+	// messages of its own (the prompt is composed per turn), so dropping
+	// the role wholesale is exact; revisit if prompt-updates ever land.
 	const settleWith = () => {
-		onFinish([...agent.state.messages], sawAbort);
+		onFinish(
+			[...agent.state.messages].filter((m) => (m as { role?: string }).role !== "system"),
+			sawAbort,
+		);
 	};
 
 	const handle = (event: AgentEvent) => {