feat: show standard OMP sessions in view-only mode

FEATURE_MATRIX.md

@@ -9,14 +9,14 @@ The README and release notes are the release contract. They must only claim beha
 | State | What it means |
 |---|---|
 | Exists today | T4 owns `packages/host-wire` and `packages/host-service`; the client protocol consumes the T4-owned wire package. |
-| Compatibility transition | The verified OMP integration binary still embeds the legacy host copy, and T4 retains a bounded read-only JSONL projector for that exact bridge. |
+| Compatibility transition | The standalone host uses the T4 bridge when available. With an official OMP release that lacks the bridge, it discovers saved sessions through the bounded JSONL projector and exposes them as explicitly labeled, view-only compatibility sessions. |
 | Planned next | Replace the embedded copy with a thin OMP launcher and authority adapter, then test supported upstream OMP versions by bridge capability instead of requiring every T4 host feature inside the fork. |
 
 ## 1. Hosts, connections, and environments
 
 | Capability | OMP authority | T3 reference | Desktop surface and required states | Priority |
 |---|---|---|---|---|
-| Local host discovery | `packages/coding-agent/src/modes/rpc/rpc-mode.ts`, planned appserver health/capabilities | `apps/web/src/routes/__root.tsx`, `packages/client-runtime/src/connection/*` | Host switcher; starting, ready, version-skew, unavailable, reconnecting, read-only, upgrade-required | Launch |
+| Local host discovery | OMP bridge when available; standard session files as a read-only fallback | `apps/web/src/routes/__root.tsx`, `packages/client-runtime/src/connection/*` | Host switcher; starting, ready, version-skew, unavailable, reconnecting, read-only, upgrade-required. Official OMP sessions remain readable and are labeled `OMP · view only`; runtime controls and activity status require the T4 bridge. | Launch |
 | Remote tailnet host | Existing collab transport plus planned appserver; current Mac/bunker topology | `packages/tailscale/src/tailscale.ts`, `packages/ssh/src/tunnel.ts`, connection supervisor | Add by MagicDNS/IP, pair, trust, connect, revoke, latency/status; never expose tokens | Launch |
 | Host capability negotiation | Planned versioned app protocol over OMP runtime | T3 contract schemas and server handshake | Show feature compatibility; disable unsupported actions with reason | Launch |
 | Multi-host operation | Planned appserver registry | T3 environments/projects | Sessions grouped by host and project; host status remains visible across switches | Launch |

apps/desktop/src/service.ts

@@ -51,7 +51,11 @@ export class OmpAppserverCompatibilityError extends Error {
       "Installed OMP is incompatible with this T4 Code build. T4 Code requires `omp appserver status --json`. Update OMP, then choose Check again.",
     );
     this.name = "OmpAppserverCompatibilityError";
-    Object.defineProperty(this, "stack", { value: undefined, enumerable: false, configurable: true });
+    Object.defineProperty(this, "stack", {
+      value: undefined,
+      enumerable: false,
+      configurable: true,
+    });
   }
 }
 
@@ -63,8 +67,16 @@ export interface OmpExecutableDiscoveryOptions {
   readonly maxOutputBytes?: number;
 }
 
-export interface OmpAppserverProbeOptions
-  extends Omit<OmpExecutableDiscoveryOptions, "homeDirectory"> {
+export interface T4HostExecutableDiscoveryOptions {
+  readonly environment?: NodeJS.ProcessEnv;
+  readonly homeDirectory?: string;
+  readonly packagedExecutable?: string;
+}
+
+export interface OmpAppserverProbeOptions extends Omit<
+  OmpExecutableDiscoveryOptions,
+  "homeDirectory"
+> {
   readonly profileId?: string;
 }
 
@@ -90,7 +102,9 @@ function isAppserverStatus(value: unknown): boolean {
       value.health.epoch.length > 0
     );
   }
-  return value.reason === "unreachable" || value.reason === "malformed" || value.reason === "failed";
+  return (
+    value.reason === "unreachable" || value.reason === "malformed" || value.reason === "failed"
+  );
 }
 
 type AppserverProbeState = "running" | "stopped" | "incompatible" | false;
@@ -129,10 +143,7 @@ async function probesAppserverStatus(
       /flag provided but not defined\s*:\s*-json\b/iu.test(diagnosticOutput)
     )
       return "incompatible";
-    if (
-      (result.exitCode !== 0 && result.exitCode !== 1) ||
-      result.stderr.trim().length > 0
-    )
+    if ((result.exitCode !== 0 && result.exitCode !== 1) || result.stderr.trim().length > 0)
       return false;
     let parsed: unknown;
     try {
@@ -156,7 +167,8 @@ export async function discoverOmpExecutable(
   const timeoutMs = options.timeoutMs ?? APP_SERVER_PROBE_TIMEOUT_MS;
   const maxOutputBytes = options.maxOutputBytes ?? APP_SERVER_PROBE_MAX_OUTPUT_BYTES;
   if (!Number.isSafeInteger(timeoutMs) || timeoutMs < 1 || timeoutMs > 10_000) return undefined;
-  if (!Number.isSafeInteger(maxOutputBytes) || maxOutputBytes < 1 || maxOutputBytes > 64 * 1024) return undefined;
+  if (!Number.isSafeInteger(maxOutputBytes) || maxOutputBytes < 1 || maxOutputBytes > 64 * 1024)
+    return undefined;
   const candidates: string[] = [];
   const explicit = environment.OMP_EXECUTABLE;
   if (explicit !== undefined && explicit.length > 0) candidates.push(explicit);
@@ -189,14 +201,57 @@ export async function discoverOmpExecutable(
     } catch {
       continue;
     }
-    const state = await probesAppserverStatus(candidate, environment, runner, timeoutMs, maxOutputBytes);
+    const state = await probesAppserverStatus(
+      candidate,
+      environment,
+      runner,
+      timeoutMs,
+      maxOutputBytes,
+    );
     if (state === "running" || state === "stopped") return candidate;
     if (state === "incompatible") incompatible = true;
   }
   if (incompatible) throw new OmpAppserverCompatibilityError();
   return undefined;
 }
 
+export async function discoverT4HostExecutable(
+  options: T4HostExecutableDiscoveryOptions = {},
+): Promise<string | undefined> {
+  const environment = options.environment ?? process.env;
+  const home = options.homeDirectory ?? homedir();
+  const candidates = [
+    options.packagedExecutable,
+    environment.T4_HOST_EXECUTABLE,
+    ...(environment.PATH ?? "")
+      .split(":")
+      .filter(Boolean)
+      .slice(0, 64)
+      .map((entry) => join(entry, "t4-host")),
+    join(home, ".local", "bin", "t4-host"),
+    join(home, "bin", "t4-host"),
+    "/usr/local/bin/t4-host",
+    "/usr/bin/t4-host",
+  ];
+  const seen = new Set<string>();
+  for (const candidate of candidates) {
+    if (
+      !candidate ||
+      seen.has(candidate) ||
+      !candidate.startsWith("/") ||
+      candidate.includes("\0") ||
+      !candidate.endsWith("/t4-host")
+    )
+      continue;
+    seen.add(candidate);
+    try {
+      await access(candidate, fsConstants.X_OK);
+      return candidate;
+    } catch {}
+  }
+  return undefined;
+}
+
 /**
  * Check every `omp` command on PATH. T4 may have its own compatible bundled
  * runtime while another shell or app launch path selects an older build,
@@ -257,22 +312,21 @@ export async function probeOmpAppserver(
     return false;
   }
   return (
-    await probesAppserverStatus(
+    (await probesAppserverStatus(
       executable,
       environment,
       runner,
       timeoutMs,
       maxOutputBytes,
       options.profileId,
-    )
-  ) === "running";
+    )) === "running"
+  );
 }
 export interface NodeServiceRunnerOptions {
   readonly environment?: NodeJS.ProcessEnv;
   readonly runner?: ProcessRunner;
 }
 
-
 export class NodeServiceRunner implements ServiceRunner {
   private readonly runner: ProcessRunner;
   private readonly environment: NodeJS.ProcessEnv;