Provider claude-agent: system messages in history are dropped, so keyed instruction updates never reach Claude #62916

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1. opencodejr commented on Nov 9, 2026

   

   opencodejrBot

   on Nov 9, 2026

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   Thanks for the detailed report. I confirmed this at the connector level on v2.2.5, and it still happens on the latest dev (617a770ae). There's no Claude account in this sandbox, so I couldn't check what the model actually answers. What I could check is the content the connector sends to Claude.

   The script below loads the claude-agent connector's own modules. It gives them the second-turn prompt OpenCode builds after an instruction update: base system prompt, user, assistant, the system message "Instructions updated: repro.state … B", then a new user question.

   • Fresh or rebuilt Claude session: ConvertToClaudeMessage.content() returns only the user and assistant turns. The update is missing.
   • Continuing a live session: Fingerprint.groups() skips the system message, so SyncDecision.decide picks start: 4, which comes after the update. CatchUp.content() then sends Claude only the new question.

   Other providers get the update, because runner/to-llm-message.ts keeps it as a system message. The baseline system parts only hold the first value, so Claude keeps A.

   The update mechanism covers every instruction source, not just plugin entries. So changes to things like AGENTS.md or MCP and skill instructions during a session probably don't reach Claude on this provider either. I haven't tested those separately.

   Related: #61248 / #61273 (plugin system parts read too early) and #61551 (forks replaying superseded instructions).

   Reproduction script (repro.ts)

   // Reproduces #62916: the claude-agent connector drops system-role messages from history,
   // which is how OpenCode delivers "Instructions updated" notices after the first request.
   // Run from an OpenCode checkout: REPO=/path/to/opencode bun /workspace/repro/repro.ts
   const repo = process.env.REPO ?? "/workspace/repo"
   const base = `${repo}/packages/core/src/plugin/provider/claude-agent`
   const { ConvertToClaudeMessage } = await import(`${base}/language-model/convert-to-claude-message.ts`)
   const { Fingerprint } = await import(`${base}/sync/fingerprint.ts`)
   const { SyncDecision } = await import(`${base}/sync/decide.ts`)
   const { CatchUp } = await import(`${base}/sync/catch-up.ts`)
   
   // The prompt OpenCode sends on the second turn after a plugin changed key repro.state from A to B.
   // (runner/to-llm-message.ts maps the stored SessionMessage.System to a role "system" message.)
   const update = "Instructions updated: repro.state\nrepro.state = B"
   const prompt: any[] = [
     { role: "system", content: "base system prompt (repro.state = A)" },
     { role: "user", content: [{ type: "text", text: "remember the value" }] },
     { role: "assistant", content: [{ type: "text", text: "ok" }] },
     { role: "system", content: update },
     { role: "user", content: [{ type: "text", text: "what is repro.state now?" }] },
   ]
   
   const text = (blocks: any[]) => blocks.map((b) => (b.type === "text" ? b.text : `[${b.type}]`)).join("\n")
   
   console.log("== ConvertToClaudeMessage.content(full prompt) (fresh/rebuilt Claude session) ==")
   const fresh = text(ConvertToClaudeMessage.content(prompt))
   console.log(fresh)
   console.log("contains update:", fresh.includes("repro.state = B"))
   
   // Continuing a live Claude session whose record already has the first user+assistant turn.
   const groups = Fingerprint.groups(prompt.slice(0, 3))
   const record: any = { history: groups.map((g: any) => ({ hash: g.hash })) }
   const decision = SyncDecision.decide(prompt, record)
   console.log("\n== continuing Claude session ==")
   console.log("groups:", Fingerprint.groups(prompt).map((g: any) => `${g.role}[${g.start},${g.end})`).join(" "))
   console.log("decision:", JSON.stringify(decision))
   const cont = text(CatchUp.content(prompt, decision.start))
   console.log("content sent to Claude:\n" + cont)
   console.log("contains update:", cont.includes("repro.state = B"))

   Run it: bun repro.ts
2. opencodejr

   added

   reproduced

   on Nov 9, 2026