revert: fix(spawn): validate OpenCode destination-pane model before dispatch (#77)

.agents/skills/harness-adapters/references/harness/opencode.md

@@ -14,7 +14,7 @@ The worker busy-state lifecycle below describes the generated OpenCode 2 plugin.
 | Resume | Relaunch with `--continue` to resume the most recent session for the current directory, then send the next instruction after the TUI is ready because `--prompt` does not auto-submit alongside `--continue`. |
 | Interactive task launch | Firstmate probes `opencode mini --help` for a `Usage: opencode mini` line; OpenCode v2 uses `opencode mini`, while legacy releases use the top-level command. Both receive the requested `--model <provider/model>` and worker brief through `--prompt`. |
 | Effort flag | None for the interactive task launch; `opencode run` has `--variant`, but that is a different, non-interactive path. |
-| Model discovery | Run `opencode models` with no argument to list every available `provider/model` identifier. The legacy `opencode models <provider>` form is rejected by OpenCode v2 ("Unexpected positional argument") and prints usage text rather than a catalog, so `../../../bin/fm-spawn.sh` reads the whole catalog and matches the exact base id. An omitted or `default` model, and any `#variant` suffix, instead resolve through `opencode debug config` read in the destination pane's settled task worktree, precedence-ranked the same way OpenCode itself ranks config sources; see `opencode_resolve_effective_model` and `opencode_model_validate` in `../../../bin/fm-spawn.sh`. |
+| Model discovery | Run `opencode models` with no argument to list every available `provider/model` identifier. The legacy `opencode models <provider>` form is rejected by OpenCode v2 ("Unexpected positional argument") and prints usage text rather than a catalog, so `../../../bin/fm-spawn.sh` reads the whole catalog and matches the exact id. |
 | Trust dialog | None. |
 | Marker | None; OpenCode publishes no identity marker, so `../../../bin/fm-harness.sh` identifies it from process ancestry. |