v2: tool.execute.before rewrite executes but chat shows pre-hook input #51596

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1. github-actions

   assigned

   jlongster

   on Sep 27, 2026
2. github-actions commented on Sep 27, 2026

   

   github-actionsBot

   on Sep 27, 2026 – with GitHub Actions

   Contributor

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   ---

   This issue might be a duplicate of existing issues. Please check:

   • tool.execute.before arg mutation is invisible to the LLM — wrappers confuse the agent #37963: tool.execute.before rewrites make wrapper commands inconsistent in the tool conversation; it discusses how rewritten command details are surfaced to the LLM.
3. jksaunders commented on Oct 8, 2026

   

   jksaunders

   on Oct 8, 2026

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   Adding macOS evidence and narrowing this to the shell tool (opencode v2.0.24, Darwin 25.6.0 arm64, /bin/zsh, latest channel).

   Same symptom: a plugin that mutates event.input.command in ctx.tool.hook("execute.before", ...) changes the command that actually runs, but the stored tool call keeps the pre-hook input. Reproduced with both:

   • the rtk wrapper plugin (git status → rtk git status), and
   • a project plugin that appends a marker comment (git status → git status # marker).

   What may be new: this looks specific to the shell tool, and it regressed relative to bash. In one session I inspected the stored messages via GET /api/session/{id}/context and checked state.input.command for each tool call:

   • bash tool calls: 19/19 stored inputs contained the injected marker.
   • shell tool calls: 0/53 stored inputs contained it.

   So under bash the execute.before mutation was written back to the message; under shell it is not. Server logs confirm the mutation still reaches execution:

   message="spawning process" command=/bin/zsh args=["-c","rtk git status # automatically rewritten ..."]
   

   while the same call's stored tool part is still git status.

   Since the bash tool persisted the mutation on the same 2.0.x server, this reads as a shell-tool regression rather than a general hook limitation.

   Repro:

   1. Register a plugin that appends a marker to event.input.command when event.tool === "shell".
   2. Run git status (or any command the rtk plugin rewrites).
   3. The server log shows the rewritten/tagged command, but the chat and the stored tool part show the original.
4. opencodejr commented on Oct 28, 2026

   

   opencodejrBot

   on Oct 28, 2026

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   Thanks for the detailed report. I reproduced this on v2.0.17. A project plugin's execute.before hook rewrites the shell command to echo REWRITTEN-BY-HOOK && <command>. The simulated model runs echo original-command. The output shows REWRITTEN-BY-HOOK, so the rewritten command ran, but the chat header still shows $ echo original-command. The recording and screenshot below show it, and the script below reproduces it.

   I couldn't confirm it on the latest dev (86ce19d) because my test harness doesn't show tool calls on that build. As far as I can tell from the code, it still runs the post-hook input but shows the model's original input. Related: #37963 (same gap, seen from the model's side), #35882, #42409.

   recording.mp4

   

   Reproduction script (drive.ts)

   // Repro for anomalyco/opencode#51596: a tool "execute.before" hook rewrites the shell
   // command; the rewritten command runs, but the TUI still shows the original command.
   import { Effect, Stream } from "effect"
   import { Llm, OpenCodeDriver } from "opencode-drive"
   
   const plugin = `export default {
     id: "rewrite-shell",
     setup: async (ctx) => {
       await ctx.tool.hook("execute.before", (event) => {
         const input = event.input as { command?: unknown }
         if (event.tool === "shell" && typeof input?.command === "string" && !input.command.startsWith("echo REWRITTEN")) {
           event.input = { ...input, command: "echo REWRITTEN-BY-HOOK && " + input.command }
         }
       })
     },
   }
   `
   
   export default OpenCodeDriver.use(
     {
       ...(process.env.OC_DEV ? { opencode: { dev: process.env.OC_DEV } } : {}),
       tui: { recording: true },
       config: { permission: { "*": "allow" } } as any,
       project: {
         git: true,
         files: { ".opencode/plugins/rewrite-shell.ts": plugin },
       },
     },
     ({ ui, llm }) =>
       Effect.gen(function* () {
         yield* llm.serve((_request, index) =>
           index === 0
             ? Stream.make(
                 Llm.toolCall({ index: 0, id: "call_shell", name: "shell", input: { command: "echo original-command" } }),
                 Llm.finish("tool-calls"),
               )
             : Stream.make(Llm.text("Done.")),
         )
         yield* ui.submit("Run echo original-command")
         yield* ui.waitFor("Done.", { timeout: 60000 } as any).pipe(Effect.catchTag("UiWaitTimeoutError", () => Effect.void))
         yield* Effect.sleep(1000)
         yield* ui.screenshot("rewritten-vs-displayed")
       }),
   )

   Run it with opencode-drive: opencode-drive run ./drive.ts. It drives opencode from your PATH; set OC_DEV to the path of an OpenCode checkout to run that from source instead.
5. opencodejr

   added

   reproduced

   on Oct 28, 2026