diff --git a/fork/manifest.json b/fork/manifest.json
index a11d63c33520..3c7139cc8dbc 100644
--- a/fork/manifest.json
+++ b/fork/manifest.json
@@ -346,6 +346,11 @@
       "marker": "fork: 5s was not enough headroom on a mu",
       "note": "Fork edit to an upstream file (+11/-1 vs baseline). Marker is a string the fork's edit introduces and upstream does not contain, so a merge that reverts the edit fails fork:verify."
     },
+    {
+      "file": "packages/core/src/installation/version.ts",
+      "marker": "InstallationReleaseChannels",
+      "note": "Fork edit to an upstream file. Adds InstallationIsRelease (channel is latest/beta/prod) alongside the existing InstallationLocal, shared by database.ts's session-db path and upgrade.ts's self-upgrade eligibility check so any non-release build — not just literally channel \"local\" — is treated as never having been published. Marker is a string the fork's edit introduces and upstream does not contain, so a merge that reverts the edit fails fork:verify."
+    },
     {
       "file": "packages/core/src/database/sqlite.bun.ts",
       "marker": "fork: this DB file is shared by every co",
@@ -408,8 +413,8 @@
     },
     {
       "file": "packages/opencode/src/cli/upgrade.ts",
-      "marker": "InstallationLocal",
-      "note": "Fork edit to an upstream file (+8/-1 vs baseline). Marker is a string the fork's edit introduces and upstream does not contain, so a merge that reverts the edit fails fork:verify."
+      "marker": "InstallationIsRelease",
+      "note": "Fork edit to an upstream file. Skips the self-upgrade check for any non-release channel (was only the literal \"local\" channel, which missed a local build on the fork's own \"dev\" channel — confirmed live: it read as needing a release patch and silently curl-installed over a running dev binary mid-session). Marker is a string the fork's edit introduces and upstream does not contain, so a merge that reverts the edit fails fork:verify."
     },
     {
       "file": "packages/opencode/src/command/index.ts",
diff --git a/packages/core/src/database/database.ts b/packages/core/src/database/database.ts
index 9b72f7a8632c..7679d63701af 100644
--- a/packages/core/src/database/database.ts
+++ b/packages/core/src/database/database.ts
@@ -7,7 +7,7 @@ import { Global } from "../global"
 import { Flag } from "../flag/flag"
 import { isAbsolute, join } from "path"
 import { DatabaseMigration } from "./migration"
-import { InstallationChannel } from "../installation/version"
+import { InstallationChannel, InstallationIsRelease } from "../installation/version"
 import { LayerNode } from "../effect/layer-node"
 import { makeGlobalNode } from "../effect/app-node"
 
@@ -57,7 +57,7 @@ export function path() {
     return join(Global.Path.data, Flag.OPENCODE_DB)
   }
   if (
-    ["latest", "beta", "prod"].includes(InstallationChannel) ||
+    InstallationIsRelease ||
     process.env.OPENCODE_DISABLE_CHANNEL_DB === "1" ||
     process.env.OPENCODE_DISABLE_CHANNEL_DB === "true"
   )
diff --git a/packages/core/src/installation/version.ts b/packages/core/src/installation/version.ts
index 25d9cd99aa6c..2462c277c9b9 100644
--- a/packages/core/src/installation/version.ts
+++ b/packages/core/src/installation/version.ts
@@ -6,3 +6,11 @@ declare global {
 export const InstallationVersion = typeof OPENCODE_VERSION === "string" ? OPENCODE_VERSION : "local"
 export const InstallationChannel = typeof OPENCODE_CHANNEL === "string" ? OPENCODE_CHANNEL : "local"
 export const InstallationLocal = InstallationChannel === "local"
+// The only channels a real published release ever carries. Anything else —
+// "local", "dev", or a one-off OPENCODE_CHANNEL override — is a build that
+// was never uploaded anywhere, so comparing its version against the latest
+// published release is meaningless and self-upgrading over it is actively
+// harmful (it silently replaces a binary someone is deliberately running for
+// its own changes, mid-session, with unrelated published code).
+export const InstallationReleaseChannels = ["latest", "beta", "prod"]
+export const InstallationIsRelease = InstallationReleaseChannels.includes(InstallationChannel)
diff --git a/packages/opencode/src/cli/upgrade.ts b/packages/opencode/src/cli/upgrade.ts
index 95160d310478..69c282843321 100644
--- a/packages/opencode/src/cli/upgrade.ts
+++ b/packages/opencode/src/cli/upgrade.ts
@@ -2,17 +2,23 @@ import { Config } from "@/config/config"
 import { AppRuntime } from "@/effect/app-runtime"
 import { Flag } from "@opencode-ai/core/flag/flag"
 import { Installation } from "@/installation"
-import { InstallationLocal, InstallationVersion } from "@opencode-ai/core/installation/version"
+import { InstallationIsRelease, InstallationVersion } from "@opencode-ai/core/installation/version"
 import { GlobalBus } from "@/bus/global"
 
 export async function upgrade() {
-  // A local dev build (working-tree dist, channel "local") must never be
-  // nudged toward a release build — 0.0.0-dev-* vs 1.x always reads as a
-  // major update. Only real installs (curl/brew/npm channels) check.
+  // Only a real published release (channel latest/beta/prod) has a
+  // meaningful version to compare against "the latest release" in the first
+  // place. A local or dev build — including a local build on the stable
+  // "dev" channel (see build-local.ts) — was never published, so the
+  // comparison is meaningless at best and actively harmful at worst: it can
+  // read as needing "a patch" and silently curl-install a real release over
+  // a binary someone is deliberately running for its own changes, mid-session
+  // (confirmed live 2026-09-19 — replaced a running dev build and corrupted
+  // the TUI's rendered screen with the installer's raw progress output).
   // OPENCODE_ALWAYS_NOTIFY_UPDATE is the explicit test hook and overrides
-  // this: it forces the toast even on a dev build, for verifying the
-  // notification path without installing a release.
-  if (InstallationLocal && !Flag.OPENCODE_ALWAYS_NOTIFY_UPDATE) return
+  // this: it forces the toast even on a non-release build, for verifying the
+  // notification path without installing anything.
+  if (!InstallationIsRelease && !Flag.OPENCODE_ALWAYS_NOTIFY_UPDATE) return
   const config = await AppRuntime.runPromise(Config.Service.use((cfg) => cfg.getGlobal()))
   if (config.autoupdate === false || Flag.OPENCODE_DISABLE_AUTOUPDATE) return
   const method = await Installation.method()