Background project-indexing run passes sessionID "dummy" (Expected a string starting with "ses") #43020

Description

Since ~Aug 6, 2026, the opencode log (~/.local/share/opencode/log/opencode.log) records a recurring ERROR from what appears to be a background (non-interactive) run:

level=ERROR message=failed error="Error: Expected a string starting with \"ses\", got \"dummy\""

Stack traces resolve entirely into bundled opencode code (/$bunfs/root/chunk-*.js, e.g. datjqaqc.js:25, cdtnt4d.js:2) — not user plugins.

Context around each occurrence

The failing run immediately performs watcher-backend and project-copy-refresh work, i.e. a background project-indexing pass separate from active sessions.

• Concurrent session streams (real ses_* IDs) continue unaffected
• No user-visible impact observed
• Frequency ~1/day on this machine

Hypothesis

A background task (project copy / watcher) invokes a session-scoped API with the placeholder sessionID dummy, which then fails session-ID validation (Expected a string starting with "ses").

Environment

• opencode 1.18.18 (also observed on earlier 1.18.x)
• Linux x86_64 (Arch), opencode installed via official script, runs as agent CLI in long-lived sessions
• Occurrences: 10 between Aug 6-17, 2026 (latest Aug 17)

Expected behavior

Background runs should either use a valid session ID or not invoke session-scoped APIs; the error suggests an internal wiring gap rather than user misconfiguration.