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Agent enters non-terminating loop, repeats identical tool calls and burns tokens #43673

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Agent enters non-terminating loop, repeats identical tool calls and burns tokens#43673
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kitlangton

Description

@rafaelxy
rafaelxy
opened on Aug 20, 2026

Description

While investigating a plugin auto-update toast, the agent got stuck in a non-terminating loop: it issued the same tool call (grep on the same file path) dozens of times in a row, each returning identical output, with no progress toward the task. It only stopped when I aborted the session. This burned a large amount of tokens with zero forward progress. There was no error, no retry/backoff, and no loop-detection — the agent just kept re-issuing the identical call.

Plugins

@cortexkit/opencode-magic-context@latest, @dietrichgebert/ponytail@latest, opencode-adaptive-thinking, oh-my-opencode-slim, @xberg-io/* (xberg, crawlberg, html-to-markdown, liter-llm, tree-sitter-language-pack), opencode-chrome-devtools, opencode-subagent-statusline (tui.json)

OpenCode version

1.18.19

Steps to reproduce

I could not reproduce, but those were the steps:

  1. Open opencode in a project with the magic-context plugin configured as @cortexkit/opencode-magic-context@latest in opencode.json (not in tui.json).
  2. Ask the agent to investigate the "Magic Context update failed" startup toast.
  3. The agent begins reading the plugin's bundled dist/index.js and repeatedly re-runs the same grep command on the same file, dozens of times, never converging.

Screenshot and/or share link

Loop log excerpt — session ses_fe06fd054ffe5bv9vlIlDYhkcU

Source: ~/.local/share/opencode/log/opencode.log (opencode 1.18.19, macOS 26.6.1, iTerm2)
Loop window: 2026-08-20 14:26:32 → 15:17:49 UTC (~51 min), aborted by user.

Stats (loop window)

  • Loop steps: step=14 → step=527 (514 iterations)
  • Identical grep -rn "auto_update" .../src/ calls: 502
  • Identical ls .../src/ calls: 492
  • No error, no backoff, no loop detection — the agent re-issued the same tool call until cancelled.

Sample — 6 consecutive identical tool calls (15:17:21 → 15:17:45)

timestamp=2026-08-20T15:17:21.074Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="grep -rn \"auto_update\" ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/ 2>/dev/null" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:21.074Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="ls ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:27.408Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="grep -rn \"auto_update\" ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/ 2>/dev/null" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:27.410Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="ls ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:32.459Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="grep -rn \"auto_update\" ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/ 2>/dev/null" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:32.459Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="ls ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:41.041Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="grep -rn \"auto_update\" ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/ 2>/dev/null" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:41.041Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="ls ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/" action.permission=bash action.pattern=* action.action=allow
timestamp=2026-08-20T15:17:45.392Z level=INFO run=d3ab2e61 message=evaluated permission=bash pattern="grep -rn \"auto_update\" ~/.cache/opencode/packages/@cortexkit/opencode-magic-context@latest/node_modules/@cortexkit/opencode-magic-context/src/ 2>/dev/null" action.permission=bash action.pattern=* action.action=allow

Loop step progression (start → end)

message=loop session.id=ses_fe06fd054ffe5bv9vlIlDYhkcU step=14   (14:26:32)
message=loop session.id=ses_fe06fd054ffe5bv9vlIlDYhkcU step=527  (15:17:45)

Termination (user abort)

timestamp=2026-08-20T15:17:49.909Z level=INFO run=d3ab2e61 message=cancel session.id=ses_fe06fd054ffe5bv9vlIlDYhkcU
timestamp=2026-08-20T15:17:49.920Z level=ERROR run=d3ab2e61 message=process session.id=ses_fe06fd054ffe5bv9vlIlDYhkcU messageID=msg_01fbfe8600016IVReGRIF4SXc0 e...

Operating System

macOS 26.6.1

Terminal

iTerm2

Activity

  1. github-actions
    assigned
    kitlangton
    on Aug 20, 2026

  2. github-actions commented on Aug 20, 2026

    @github-actions
    github-actionsBot
    on Aug 20, 2026 – with GitHub Actions
    Contributor

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

    If your issue adds new context (e.g., the specific plugin interaction or the 51-minute / 514-iteration scale), please mention that on the existing issue rather than opening a new one.

  3. jagnd1 commented on Aug 21, 2026

    @jagnd1
    jagnd1
    on Aug 21, 2026

    Confirmed same class of bug in a fresh session with NO plugins, opencode 1.18.19, model opencode-go/deepseek-v4-flash (macOS ARM64). This rules out a plugin-triggered cause and suggests a general missing loop-detection issue.

    Findings / observations:

    1. Triggers were not all identical in shape — observed loops where the agent re-issued:
      • the same file read repeatedly,
      • the same git add/git commit repeatedly,
      • the same git status check repeatedly.
        In every case it re-emitted an identical tool call instead of executing once and moving on, with no self-correction until interrupted.
    2. It is intermittent, not deterministic — a long multi-phase task (many sequential edits/commits/tests) progressed normally for a while, then entered a loop, then after interruption resumed normally.
    3. Mitigation that worked for us: interrupting immediately (at the 2nd repeat) and issuing one explicit command per step (rather than letting it chain/repeat) let the work continue. Adding a hard rule "never repeat the same tool call twice; move on" to the session guidance also reduced occurrences.
    4. Impact: each repetition consumes tokens; in a billing-metered session this caused significant token/billing swell and stalled progress.

    Environment: opencode 1.18.19, deepseek-v4-flash, macOS 25.5.0 (Darwin ARM64/T6020), Node v26.5.0, no plugins.

    Hope the loop/no-progress detection + circuit breaker (as referenced in #31942) lands soon.

  4. agentgoblin commented on Aug 27, 2026

    @agentgoblin
    agentgoblin
    on Aug 27, 2026

    How about doom_loop permission? #45442 (comment)

  5. jagnd1 commented on Aug 29, 2026

    @jagnd1
    jagnd1
    on Aug 29, 2026

    Thanks @agentgoblin — the doom_loop pointer (#45442) was exactly it. I've verified on opencode 1.18.20 / deepseek-v4-flash:

    • With "permission": { "doom_loop": "deny" }, prompting five identical ls -la calls, the 3rd identical call is blocked (...prevents you from using this specific tool call... doom_loop deny) and the session ends instead of looping.
    • Your framing is right: the root cause is long-context degenerate repetition in the model, but the framework must protect against it — doom_loop is that protection.

    For anyone hitting the identical-call loop: set doom_loop to deny (the default is ask, which won't protect --auto/unattended sessions). This covers the 514-iteration grep/ls case here and the read/git loops in #43800.

    Appreciate the fast help — leaving this issue open for @rafaelxy to weigh in if they want to add their repro/close it too.

  6. rafaelxy commented on Aug 31, 2026

    @rafaelxy
    rafaelxy
    on Aug 31, 2026
    Author

    @jagnd1 @agentgoblin Thanks the doom_loop seems fitting and I enabled it!

  7. rafaelxy
    closed this as completedon Aug 31, 2026
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