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feat: OPENCODE_TOOL_CHOICE=required for agent tool binding #14

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Merged
TimothyVang merged 1 commit into from
Jul 9, 2026
Merged

feat: OPENCODE_TOOL_CHOICE=required for agent tool binding #14

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12 changes: 12 additions & 0 deletions packages/core/src/flag/flag.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -75,4 +75,16 @@ export const Flag = {
get OPENCODE_CLIENT() {
return process.env["OPENCODE_CLIENT"] ?? "cli"
},
/**
* When `OPENCODE_TOOL_CHOICE=required` (or `VERDICT_FORCE_TOOL_CHOICE=1`),
* non-final agent steps send OpenAI-compatible `tool_choice: "required"`
* so local models cannot answer with prose/JSON instead of tool calls.
* Final step still forces `none` (max-steps exit).
*/
get OPENCODE_TOOL_CHOICE() {
const raw = (process.env["OPENCODE_TOOL_CHOICE"] ?? "").toLowerCase()
if (raw === "required" || raw === "auto" || raw === "none") return raw
if (truthy("VERDICT_FORCE_TOOL_CHOICE")) return "required"
return undefined
},
}
13 changes: 12 additions & 1 deletion packages/core/src/session/runner/llm.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ import {
import { Cause, DateTime, Effect, FiberSet, Layer, Option, Semaphore, Stream } from "effect"
import { AgentV2 } from "../../agent"
import { Config } from "../../config"
import { Flag } from "../../flag/flag"
import { Database } from "../../database/database"
import { EventV2 } from "../../event"
import { Location } from "../../location"
Expand Down Expand Up @@ -205,7 +206,17 @@ const layer = Layer.effect(
.map(SystemPart.make),
messages: [...toLLMMessages(context, model), ...(isLastStep ? [Message.assistant(MAX_STEPS_PROMPT)] : [])],
tools: toolMaterialization?.definitions ?? [],
toolChoice: isLastStep ? "none" : undefined,
// Default: auto (undefined). OPENCODE_TOOL_CHOICE=required forces tool
// calls on non-final steps so weak local models cannot print JSON prose.
toolChoice: isLastStep
? "none"
: Flag.OPENCODE_TOOL_CHOICE === "required"
? "required"
Comment on lines +213 to +214

@chatgpt-codex-connector chatgpt-codex-connector Bot Jul 9, 2026

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P2 Badge Preserve a final turn when forcing tool choice

When OPENCODE_TOOL_CHOICE=required or VERDICT_FORCE_TOOL_CHOICE=1 is set for an agent without a configured steps limit (the built-in build agent leaves steps unset), isLastStep never becomes true, so every provider turn is sent with toolChoice: "required". Any local tool call then sets needsContinuation and the runner starts another turn that again cannot produce a final text answer, causing default sessions to keep issuing tools until an error/context limit instead of settling. Only force required when there is a finite final step or otherwise disable it after tool settlement.

Useful? React with 👍 / 👎.

: Flag.OPENCODE_TOOL_CHOICE === "none"
? "none"
: Flag.OPENCODE_TOOL_CHOICE === "auto"
? "auto"
: undefined,
})
if (yield* compaction.compactIfNeeded({ sessionID: session.id, entries, model, request }))
return yield* Effect.die(continueAfterCompaction(currentStep))
Expand Down
36 changes: 36 additions & 0 deletions packages/core/test/tool-choice-flag.test.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
import { describe, expect, test } from "bun:test"

describe("OPENCODE_TOOL_CHOICE / VERDICT_FORCE_TOOL_CHOICE", () => {
test("reads required from OPENCODE_TOOL_CHOICE", async () => {
const prev = process.env["OPENCODE_TOOL_CHOICE"]
const prevForce = process.env["VERDICT_FORCE_TOOL_CHOICE"]
try {
delete process.env["VERDICT_FORCE_TOOL_CHOICE"]
process.env["OPENCODE_TOOL_CHOICE"] = "required"
// Re-import would cache Flag getters — getters read process.env at access time.
const { Flag } = await import("../src/flag/flag")
expect(Flag.OPENCODE_TOOL_CHOICE).toBe("required")
} finally {
if (prev === undefined) delete process.env["OPENCODE_TOOL_CHOICE"]
else process.env["OPENCODE_TOOL_CHOICE"] = prev
if (prevForce === undefined) delete process.env["VERDICT_FORCE_TOOL_CHOICE"]
else process.env["VERDICT_FORCE_TOOL_CHOICE"] = prevForce
}
})

test("VERDICT_FORCE_TOOL_CHOICE=1 maps to required", async () => {
const prev = process.env["OPENCODE_TOOL_CHOICE"]
const prevForce = process.env["VERDICT_FORCE_TOOL_CHOICE"]
try {
delete process.env["OPENCODE_TOOL_CHOICE"]
process.env["VERDICT_FORCE_TOOL_CHOICE"] = "1"
const { Flag } = await import("../src/flag/flag")
expect(Flag.OPENCODE_TOOL_CHOICE).toBe("required")
} finally {
if (prev === undefined) delete process.env["OPENCODE_TOOL_CHOICE"]
else process.env["OPENCODE_TOOL_CHOICE"] = prev
if (prevForce === undefined) delete process.env["VERDICT_FORCE_TOOL_CHOICE"]
else process.env["VERDICT_FORCE_TOOL_CHOICE"] = prevForce
}
})
})
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