Fix Linux terminal fd leak: bump node-pty to close inherited fds (#1127)

**Long-lived Kolu sessions on Linux leak a `/dev/ptmx` master fd into
every shell spawned after the first**, and those leaked masters ride
along into each shell's children — the suspected cause of the [frozen
split-terminal after a raw-mode TUI exits
(#1076)](#1076), plus a steady fd
leak that pressures `EMFILE` in busy sessions. The root cause was a
**stale node-pty fork**: our pin (`fix/darwin-pty-fd-leak`) branched
2025-12-21 and sat **127 commits behind upstream**, predating the Linux
fix for exactly this.

This repoints node-pty to a refreshed fork branch and drops a fork patch
that has since landed upstream.

### What changed

| | Before (`fix/darwin-pty-fd-leak`) | After
(`feat/foreground-pid-dist`) |
| --- | --- | --- |
| Base | upstream @ 2025-12-21 | upstream `main` (2026-05-18) |
| Linux fd-close fix
([`52417d516`](microsoft/node-pty@52417d516))
| ❌ missing | ✅ included |
| `foregroundPid` accessor | ✅ (fork patch) | ✅ (same patch, now also
[PR #918](microsoft/node-pty#918)) |
| macOS `/dev/ptmx` fix (#882) | fork patch | dropped — now upstream |
| built `lib/` for git install | ✅ | ✅ |

Upstream `52417d516` closes inherited fds in the `forkpty()` child
before `exec` (`close_range(2)` → `/proc/self/fd` fallback). macOS was
never affected (`POSIX_SPAWN_CLOEXEC_DEFAULT`), which is why this bug is
**Linux-only**.

### Verification

Measured on this branch with the rebuilt addon:

- **Leak gone:** a 2nd shell spawned after the first now reports **0**
leaked `/dev/ptmx` fds (it was **1** before — confirmed in a real Kolu
split sub-terminal, whose shell held `fd 29 -> /dev/ptmx`, the main
terminal's master).
- **`foregroundPid` intact:** resolves to the foreground pgid (`==
pid`), so `pty-host`'s spawn-time sanity check still passes — agent/Dock
foreground detection unaffected.
- `just check` clean; native `pty.node` compiles under nix (`node-gyp
rebuild`).

### Fork housekeeping

The upstreaming of `foregroundPid` is
[microsoft/node-pty#918](microsoft/node-pty#918)
(rebased here, mergeable, awaiting maintainer review). Once it merges,
the fork shrinks to just the committed-`lib/` packaging shim — and could
be retired entirely if we build node-pty from source in the nix
derivation.

Refs #1076.

_Generated by Claude Code (model `claude-opus-4-8`)._

Author: srid

default.nix

@@ -58,7 +58,7 @@ let
     # hash-fresh` enforces this stays in sync with pnpm-lock.yaml by forcing
     # fetchPnpmDeps to re-execute (--rebuild), so stale artifacts in the
     # binary cache can't silently satisfy a hash that no longer matches.
-    hash = "sha256-etT3O4sLpavhfLbhNYfFZ8418OOVPj//N0yt1ekychQ=";
+    hash = "sha256-qAGpemq4TbjJgs6u2FaGiXl728K5zTe72+e1Xe+qI9g=";
     fetcherVersion = 3;
   };
 

packages/pty-host/package.json

@@ -23,7 +23,7 @@
     "kolu-common": "workspace:*",
     "kolu-pty": "workspace:*",
     "kolu-shared": "workspace:*",
-    "node-pty": "github:juspay/node-pty#fix/darwin-pty-fd-leak",
+    "node-pty": "github:juspay/node-pty#feat/foreground-pid-dist",
     "zod": "^4.3.6"
   },
   "devDependencies": {