feat: port remaining Tier 1+2 upstream fixes and features

Tier 1 bug fixes:
- Fix O(n²) bash output concatenation with StreamingOutput class (anomalyco#9693)
- Fix memory leaks in Bus.once, Format, Plugin, ShareNext, Bootstrap (anomalyco#13514)
- Fix FileTime race condition using actual file mtime instead of JS clock
- Free memory on compaction prune: clear output/attachments/metadata (anomalyco#7049)
- Throttle reasoning-delta storage writes to 50ms intervals (anomalyco#11328)
- Handle SIGHUP/SIGTERM to prevent orphaned processes (anomalyco#12718)
- Add process.once("close") handler for bash tool reliability

Tier 2 features:
- Support 1M context window for Anthropic models via beta header (anomalyco#14375)
- Input-only token counting for compaction with limit.input models
- MCP lazy loading: on-demand tool discovery via mcp_search tool (anomalyco#8771)
- MCP servers listed in system prompt when lazy mode enabled
- StreamingOutput: output_filter regex for build diagnostics
- LSP server cleanup callback for temp directory removal
- Extract formatSize utility from uninstall to shared util/format
- GitHub CI: fix Bus subscription leak in session event handler

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: EBrown

packages/opencode/src/bus/index.ts

@@ -80,6 +80,7 @@ export namespace Bus {
     const unsub = subscribe(def, (event) => {
       if (callback(event)) unsub()
     })
+    return unsub
   }
 
   export function subscribeAll(callback: (event: any) => void) {

packages/opencode/src/cli/cmd/github.ts

@@ -483,6 +483,7 @@ export const GithubRunCommand = cmd({
       let session: { id: string; title: string; version: string }
       let shareId: string | undefined
       let exitCode = 0
+      let unsubSessionEvents: (() => void) | undefined
       type PromptFiles = Awaited<ReturnType<typeof getUserPrompt>>["promptFiles"]
       const triggerCommentId = isCommentEvent
         ? (payload as IssueCommentEvent | PullRequestReviewCommentEvent).comment.id
@@ -533,7 +534,7 @@ export const GithubRunCommand = cmd({
             },
           ],
         })
-        subscribeSessionEvents()
+        unsubSessionEvents = subscribeSessionEvents()
         shareId = await (async () => {
           if (share === false) return
           if (!share && repoData.data.private) return
@@ -671,6 +672,7 @@ export const GithubRunCommand = cmd({
         // Also output the clean error message for the action to capture
         //core.setOutput("prepare_error", e.message);
       } finally {
+        unsubSessionEvents?.()
         if (!useGithubToken) {
           await restoreGitConfig()
           await revokeAppToken()
@@ -868,7 +870,7 @@ export const GithubRunCommand = cmd({
         }
 
         let text = ""
-        Bus.subscribe(MessageV2.Event.PartUpdated, async (evt) => {
+        return Bus.subscribe(MessageV2.Event.PartUpdated, async (evt) => {
           if (evt.properties.part.sessionID !== session.id) return
           //if (evt.properties.part.messageID === messageID) return
           const part = evt.properties.part

packages/opencode/src/cli/cmd/serve.ts

@@ -11,6 +11,12 @@ export const ServeCommand = cmd({
   builder: (yargs) => withNetworkOptions(yargs),
   describe: "starts a headless opencode server",
   handler: async (args) => {
+    for (const signal of ["SIGHUP", "SIGTERM"] as const) {
+      process.once(signal, () => {
+        process.kill(process.pid, signal)
+      })
+    }
+
     if (!Flag.OPENCODE_SERVER_PASSWORD) {
       console.log("Warning: OPENCODE_SERVER_PASSWORD is not set; server is unsecured.")
     }

packages/opencode/src/cli/cmd/tui/attach.ts

@@ -40,6 +40,12 @@ export const AttachCommand = cmd({
         describe: "basic auth password (defaults to OPENCODE_SERVER_PASSWORD)",
       }),
   handler: async (args) => {
+    for (const signal of ["SIGHUP", "SIGTERM"] as const) {
+      process.once(signal, () => {
+        process.kill(process.pid, signal)
+      })
+    }
+
     const unguard = win32InstallCtrlCGuard()
     try {
       win32DisableProcessedInput()

packages/opencode/src/cli/cmd/tui/thread.ts

@@ -162,6 +162,13 @@ export const TuiThreadCommand = cmd({
         worker.terminate()
       }
 
+      for (const signal of ["SIGHUP", "SIGTERM"] as const) {
+        process.once(signal, async () => {
+          await client.call("shutdown", undefined).catch(() => {})
+          process.kill(process.pid, signal)
+        })
+      }
+
       const prompt = await input(args.prompt)
       const config = await Instance.provide({
         directory: cwd,

packages/opencode/src/cli/cmd/tui/worker.ts

@@ -33,6 +33,26 @@ process.on("uncaughtException", (e) => {
   })
 })
 
+for (const signal of ["SIGHUP", "SIGTERM"] as const) {
+  process.once(signal, () => {
+    rpc.shutdown().finally(() => {
+      process.kill(process.pid, signal)
+    })
+  })
+}
+
+if (process.platform !== "win32") {
+  const monitor = setInterval(() => {
+    // Avoid stale parent PID checks; rely on reparent-to-init (ppid=1) instead.
+    if (process.ppid !== 1) return
+    clearInterval(monitor)
+    rpc.shutdown().finally(() => {
+      process.kill(process.pid, "SIGTERM")
+    })
+  }, 2000)
+  monitor.unref()
+}
+
 // Subscribe to global events and forward them via RPC
 GlobalBus.on("event", (event) => {
   Rpc.emit("global.event", event)

packages/opencode/src/cli/cmd/uninstall.ts

@@ -3,6 +3,7 @@ import { UI } from "../ui"
 import * as prompts from "@clack/prompts"
 import { Installation } from "../../installation"
 import { Global } from "../../global"
+import { formatSize } from "../../util/format"
 import { $ } from "bun"
 import fs from "fs/promises"
 import path from "path"
@@ -340,13 +341,6 @@ async function getDirectorySize(dir: string): Promise<number> {
   return total
 }
 
-function formatSize(bytes: number): string {
-  if (bytes < 1024) return `${bytes} B`
-  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`
-  if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`
-  return `${(bytes / (1024 * 1024 * 1024)).toFixed(1)} GB`
-}
-
 function shortenPath(p: string): string {
   const home = os.homedir()
   if (p.startsWith(home)) {

packages/opencode/src/config/config.ts

@@ -1190,6 +1190,12 @@ export namespace Config {
             .positive()
             .optional()
             .describe("Timeout in milliseconds for model context protocol (MCP) requests"),
+          mcp_lazy: z
+            .boolean()
+            .optional()
+            .describe(
+              "Enable lazy loading of MCP tools. When enabled, MCP tools are not loaded into context automatically. Instead, use the mcp_search tool to discover and call MCP tools on-demand.",
+            ),
           tool_aliases: z
             .record(z.string(), z.string())
             .optional()

packages/opencode/src/file/time.ts

@@ -9,24 +9,36 @@ export namespace FileTime {
   // All tools that overwrite existing files should run their
   // assert/read/write/update sequence inside withLock(filepath, ...)
   // so concurrent writes to the same file are serialized.
-  export const state = Instance.state(() => {
-    const read: {
-      [sessionID: string]: {
-        [path: string]: Date | undefined
+  export const state = Instance.state(
+    () => {
+      const read: {
+        [sessionID: string]: {
+          [path: string]: Date | undefined
+        }
+      } = {}
+      const locks = new Map<string, Promise<void>>()
+      return {
+        read,
+        locks,
       }
-    } = {}
-    const locks = new Map<string, Promise<void>>()
-    return {
-      read,
-      locks,
-    }
-  })
+    },
+    async (current) => {
+      for (const key of Object.keys(current.read)) {
+        delete current.read[key]
+      }
+      current.locks.clear()
+    },
+  )
 
   export function read(sessionID: string, file: string) {
     log.info("read", { sessionID, file })
     const { read } = state()
     read[sessionID] = read[sessionID] || {}
-    read[sessionID][file] = new Date()
+    // Use the file's actual mtime when available so the assert() comparison
+    // is filesystem-time vs filesystem-time. Using new Date() caused false
+    // positives on Windows where NTFS mtime can lag behind JS clock.
+    const mtime = Filesystem.stat(file)?.mtime
+    read[sessionID][file] = mtime ?? new Date()
   }
 
   export function get(sessionID: string, file: string) {

packages/opencode/src/format/index.ts

@@ -101,9 +101,12 @@ export namespace Format {
     return result
   }
 
+  let unsub: (() => void) | undefined
+
   export function init() {
     log.info("init")
-    Bus.subscribe(File.Event.Edited, async (payload) => {
+    unsub?.()
+    unsub = Bus.subscribe(File.Event.Edited, async (payload) => {
       const file = payload.properties.file
       log.info("formatting", { file })
       const ext = path.extname(file)