[Bug]: OpenCode CLI OSC title leak pollutes agent inventory — Agent not found → UnknownError

Bug

OpenCode <=1.18 writes OSC title sequence ESC ]0;<cwd>: ready BEL to stdout for every non-help command even when stdout is a pipe. T3 captures that via ChildProcessSpawner + collectStreamAsString and the parsers stored a polluted agent id:

Agent not found: "\u001b]0;imbios: ready\u0007build". Available agents: build, explore, general, plan

Followed by generic wrapper:

UnknownError: UnknownError
    at <anonymous> (//root/chunk-09733s3k.js:1096:2069)
    at SessionPrompt.createUserMessage (//root/chunk-09733s3k.js:1096:9954)
    ...
    at SessionHttpApi.promptAsync (//root/chunk-ys5kjase.js:2:84381)

Evidence

• ~/.t3/userdata/logs/provider/events.*.log shows two session.error per turn: first is the polluted agent, second is the generic UnknownError.
• projection_threads.model_selection_json polluted for 3 threads:

{"instanceId":"opencode","model":"opencode-go/mimo-v2.5","options":[{"id":"agent","value":"\u001b]0;imbios: ready\u0007build"}]}

• Repro: opencode agent list 2>&1 | cat -v → ^[]0;tmp: ready^Gbuild (primary) even with env -i PATH=... opencode agent list and TERM=dumb — opencode binary itself leaks, not shell/ghostty.
• Also opencode models --verbose 2>&1 | cat -v → ^[]0;tmp: ready^Gopencode/big-pickle — caused model inventory to drop to 0 without the fix (SLUG_RE didn't match). Skills JSON degraded to [].

Root cause

apps/server/src/provider/opencodeRuntime.ts:208,270 parseModelsCliOutput/parseAgentListCliOutput assumed clean stdout. No strip of OSC ESC ]...BEL / CSI ESC[...m.

Fix

See PR from fork (ImBIOS/t3code#2 merged to ImBIOS:main, will open upstream PR). Summary:

• packages/shared/src/stripTerminalEscapes.ts: shared stripTerminalEscapes/sanitizeTerminalValue
• opencodeRuntime.ts: strip before parseModels/Agent/Skills, defensive at entry
• OpenCodeProvider.ts: sanitize inventory agent names/variants + --version parsing
• OpenCodeAdapter.ts + OpenCodeTextGeneration.ts: sanitize stored agent/variant before session.promptAsync
• packages/shared/src/model.ts: sanitize persisted option values and model slugs on read (repairs polluted threads without DB migration)
• Tests: regression cases for OSC/ANSI in both parsers

Upstream

Should be fixed in sst/opencode as well: CLI should write OSC title to /dev/tty/stderr only when isTTY, not stdout pipe. T3 fix is defensive regardless.

Repro steps

1. opencode agent list | cat -v shows OSC prefix
2. Start T3 server, no external opencode server → loadInventoryFromCli stores polluted agent
3. New thread → send → fails with UnknownError stack

Expected

Clean agent inventory, no OSC leak.

Start at apps/server/src/provider/opencodeRuntime.ts, especially parseModelsCliOutput and parseAgentListCliOutput, and trace how their results reach the provider and persisted model options. Review packages/shared/src/stripTerminalEscapes.ts, OpenCodeProvider.ts, OpenCodeAdapter.ts, OpenCodeTextGeneration.ts, and packages/shared/src/model.ts. Done means OSC and ANSI output no longer pollute inventories, prompts, or stored values, with regression cases covering both parsers.