opencode 2.0.16: context event tools have no execute() — plugin inert; port to tool.hook execute.before (+ snip is a wrapper, not a pipe filter) #4

opencode 2.0.16: context event tools have no execute() — plugin inert; port to ctx.tool.hook("execute.before") (+ snip is a command wrapper, not a pipe filter)

Summary. On opencode 2.0.16 (verified on the OpenChamber 2.0.16 AppImage's bundled binary), the session.context event's tools are bare {description, input} definitions — no execute — so the plugin's execute wrapping loads but wraps nothing. Separately, the "append | snip" design is dead regardless of version: the current snip binary (edouard-claude/tap) is a command wrapper (snip <cmd> / snip run -- <cmd>), does not read stdin, and piping into it just prints help.

2.0.16 plugin API facts (probe-verified, 2026-09-25):

• ctx.tool.hook("execute.before", fn) exists and mutates what executes: fn({tool, input}), assign a.input.command. Present in both 2.0.12 and 2.0.16.
• event.tools[...].execute in the session.context hook: absent in 2.0.16 (present in 2.0.12) — the old wrapping pattern no-ops.
• ctx.session.context({sessionID}) returns minimal entries (id/time/type/text; types user/idle/synthetic) — no assistant entries, no tokens; do not build token accounting on it.
• No chat.message/chat.transform hooks in 2.0.16.
• Plugin modules must export {id, setup}; a bare default function fails to load (SchemaError).

Working rewrite strategy (verified local port). Wrap the first pipe segment as a prefix:

ps aux | head -5   →   snip ps aux | head -5

(snip filters segment 1; downstream segments run normally.) Required guards, all verified by unit test (10/10 pass):

• skip multi-line commands (newlines are command separators — snip SID=$(...) → fork/exec SID=...: no such file or directory in practice);
• skip leading variable assignments (VAR=... is not runnable as a command);
• skip compounds (;, &&, ||), redirects in the first segment (>), snip/lowfat-prefixed commands, and no-output builtins (cd, echo, mkdir, ...);
• skip if snip is not on PATH (resolve via command -v at setup).

Evidence from the live 2.0.16 server: before the guard fix, a multi-line SID=$(...)+curl command was wrapped and failed with snip: passthrough: fork/exec SID=...: no such file or directory; after the fix the same shape passes through unwrapped. Simple commands execute as snip <cmd> as intended.