Carl-OOTB Windows Phase 4: rustc 1.94.0 ICE compiling continuum-core lib (auto-launch fails)

[joelteply]

airc-queue card

Coordinates work via the AIRC queue substrate (airc#562). Edit this card by commenting OR by running airc queue claim/airc queue release/airc queue heartbeat (later PRs).

{
  "kind": "airc-queue-card-v1",
  "id": "#1007",
  "owner": "claude-tab-2",
  "status": "claimed",
  "evidence": "Adopted existing GitHub issue into airc queue.",
  "next_action": "Triage, claim, or close this adopted backlog card."
}

Close this issue when the work is done (status=merged/abandoned).

Original issue body

Pre-adoption body

Found during Carl-OOTB Windows validation 2026-05-02 by continuum-b69f, on Windows 11 + WSL2 Ubuntu + RTX 5090 (CUDA available).

Status

• Phase 1 (prereqs): ✅ pass after PR fix(install.ps1): WSL detection — strip null bytes from UTF-16 wsl --list output #1005 (WSL detection fix)
• Phase 2 (bootstrap.sh in WSL): ✅ pass after WSL networking reset (separately Carl-OOTB Windows: bootstrap.sh fetch fails — WSL2 cannot reach raw.githubusercontent.com (Phase 2 blocker) #1006)
• Phase 3 (Tower install — system deps, Node, Rust, Python ML, Postgres, LiveKit): ✅ all 8 steps green
• Phase 4 (Rust workers build during auto-launch): ❌ rustc 1.94.0 ICE

Symptom

After Building Continuum / TypeScript compilation succeeded ✅, install.sh's auto-launch path (npm start → bash scripts/parallel-start.sh) re-invokes the Rust build, which crashes:

[Rust] error: the compiler unexpectedly panicked. this is a bug.
[Rust] note: rustc 1.94.0 (4a4ef493e 2026-03-02) running on x86_64-unknown-linux-gnu
[Rust] note: compiler flags: --crate-type cdylib --crate-type rlib -C opt-level=3 -C strip=symbols -C link-arg=-Wl,--allow-multiple-definition
[Rust] query stack during panic:
[Rust] #0 [early_lint_checks] perform lints prior to AST lowering
[Rust] #1 [hir_crate] getting the crate HIR
[Rust] error: could not compile `continuum-core` (lib); 7 warnings emitted

Caused by a continuum-core lib compile in /home/joel/continuum/src/workers/. Crate features active when ICE fired: cuda, default, livekit-webrtc, load-dynamic-ort.

Why this matters for Carl-OOTB

A fresh-Windows user running irm install.ps1 | iex:

1. PR fix(install.ps1): WSL detection — strip null bytes from UTF-16 wsl --list output #1005 unblocks Phase 1.
2. After their first reboot, Phase 2 works.
3. Install proceeds through all 8 install steps and reports ✅ Continuum Tower installed!.
4. Auto-launch immediately rebuilds Rust workers in release mode and hits this ICE.
5. They never get to a working chat.

Suggested fix surfaces (not implemented in this issue)

1. Skip the auto-launch Rust rebuild when a fresh build already completed in step 5/8 of the install. Right now the install builds, reports success, then the auto-launch IMMEDIATELY rebuilds — same code, same toolchain, same target dir. The second build is redundant and (when it ICEs) breaks the OOTB flow.
2. Lower opt-level for the auto-launch rebuild. rustc ICEs are sometimes -C opt-level=3 specific; falling back to opt-level=2 on ICE could complete.
3. Pin rustc to a version known to compile this codebase. 1.94.0 is current stable; if 1.93.x or 1.95.x works, the rust-toolchain.toml could pin.
4. Catch the ICE and surface a recovery hint ("rustup update; cargo clean; cargo build --release"). Today it's just walls of stack trace + script exit.

Repro

Windows 11, WSL2 Ubuntu + RTX 5090, post-Phase-3 Continuum Tower install completes successfully. The auto-launch's Rust rebuild ICEs deterministically.

Workaround used

I'll try cargo clean && cargo build from the WSL continuum dir to see if a fresh build works, separately from the install.ps1 chain.

— continuum-b69f