Claude Fable 5 in Zed

Setup

Pick your path first — the steps diverge immediately.

1. 1

   Decide: native BYOK or Claude Agent (ACP)

   Native BYOK talks to the Claude API with your own key and bills per token. The Claude Agent path runs Claude Code as a subprocess over ACP, so it can use a Pro/Max subscription instead of an API key. Fable 5 works reliably on the first path today; the second depends on your bridge version.

2. 2

   BYOK: add your Anthropic key and accept retention

   Add your Anthropic API key to the Anthropic provider in Zed settings, then open Settings → Privacy and enable telemetry.anthropic_retention. It ships off by default. Anthropic retains inference logs for 30 days on Fable 5, so without consent Zed raises a typed, non-retryable error in the completion path rather than sending the request.

3. 3

   BYOK: select Claude Fable 5 in the model picker

   With consent on, Claude Fable 5 appears in the Anthropic section of the agent panel model picker. If Fable 5 declines a request, Zed transparently falls back to Claude Opus 4.8 and the panel shows a callout with Switch to Opus 4.8 and Accept actions that resume the failed turn, so you do not retype your message.

4. 4

   ACP: check your claude-agent-acp version

   The fix for issue #762 landed in @agentclientprotocol/claude-agent-acp 0.55.0, which also carries the modelOverrides allowlist fix from 0.54.1 and the refusal-fallback consent dialog. Check what you actually have with npx @agentclientprotocol/claude-agent-acp --version, and pin 0.55.0 or newer in your agent server configuration if Zed is launching an older bundled copy.

5. 5

   Workaround: run Claude Code directly

   If you cannot move the bridge version, drop to Zed's terminal and run claude --model claude-fable-5. Claude Code has accepted that ID since launch — the reporter in issue #762 verified that passing it through to query.setModel() works. This is the only path that is not gated by a client-side allowlist.

Gotchas

Every one of these was reported by someone who lost an afternoon to it.

• The error you get is not model_not_found

  When the bridge rejects the ID you get a generic config-option error, not Claude Code's clean model_not_found. That is the tell: Claude Code returns a proper typed error with errorKind: model_not_found for a genuinely nonexistent model such as claude-fable-6, so a vague validation message means the request never left your machine.

• Zero Data Retention orgs cannot use Fable 5 at all

  This is an Anthropic-side constraint, not a Zed bug: Fable 5 is not offered under ZDR because inference logs are retained for 30 days. Zed models that as a hard, non-retryable check in the cloud completion path. If your org enforces ZDR, no amount of client configuration will make this work.

• Writing model into ~/.claude/settings.json does not help

  A separate long-running issue (claude-agent-acp#225) documents that the bridge calls query.supportedModels() and simply picks the first entry, ignoring the model preference in your Claude Code settings file. So the obvious workaround — set the model where Claude Code reads it — does not route through ACP.

• Selecting Fable, running Opus

  One user on claude-agent-acp 0.44.0 reported that Fable appeared in configOptions and the agent echoed the selection back, but the work was processed by Opus 4.8. They only caught it with ccusage, which showed no Fable consumption while the same model used from the Claude CLI did. If the model selection matters to you, verify against usage data rather than the picker.

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