claude-code provider cannot decode `claude --print` output: CLI 2.x returns an event array, parse_envelope expects an object

[fedorovvvv]

What happens

forgeplan reason fails on a correctly configured, logged-in claude-code provider:

$ forgeplan reason RFC-001
  Analyzing RFC-001 with ADI cycle (claude-code/claude-sonnet-5)...
Error: ADI reasoning failed: claude-code provider: failed to decode `claude --print` JSON envelope: invalid type: map, expected a boolean at line 1 column 1. Is `claude` logged in? Try `claude login`.
Error: LLM call failed

The remediation text points at authentication, which sends you to claude login, claude auth, and a re-check of .forgeplan/secrets.env. None of it is the problem — the session is logged in and claude --print works fine on its own.

Root cause

claude --print --output-format json on claude CLI 2.x returns a JSON array of stream events. The envelope is the final {"type": "result", ...} entry:

[
  {"type": "system", "subtype": "init", "session_id": "...", "tools": [...]},
  {"type": "assistant", "message": {...}},
  {"type": "result", "subtype": "success", "is_error": false, "result": "...", "session_id": "..."}
]

parse_envelope (crates/forgeplan-core/src/playbook/dispatch/claude_print.rs:485) decodes stdout straight into ClaudePrintResponse:

pub(crate) fn parse_envelope(stdout: &[u8]) -> Result<ClaudePrintResponse, serde_json::Error> {
    let s = String::from_utf8_lossy(stdout);
    serde_json::from_str(s.trim())
}

serde deserialises a JSON array into a struct positionally. The first field of ClaudePrintResponse is is_error: bool, so element 0 — {"type": "system", ...} — is fed to it, giving invalid type: map, expected a boolean at line 1 column 1. The column-1 position is what makes it look like malformed output rather than a shape mismatch.

Blast radius

parse_envelope is pub(crate) and has two consumers, so both paths are affected:

• crate::llm — the claude-code provider (llm/mod.rs:247). This is the reported symptom: forgeplan reason is dead, and with it every Standard+ FPF ADI gate that runs before activation.
• playbook::dispatch — AgentDispatcher and PluginDispatcher (claude_print::invoke, line 683).

The existing tests do not catch it because every fixture uses the bare-object shape (json_response() in claude_print::tests, write_mock_claude() in llm::claude_code_tests) — the shape the CLI emitted when #382 landed.

Repro

# 1. see the actual shape
echo hi | claude --print --output-format json | jq 'type'     # => "array"

# 2. configure the provider — no API key needed, it reuses `claude login`
cat >> .forgeplan/config.yaml <<'YAML'
llm:
  provider: claude-code
  model: claude-sonnet-5
YAML

# 3. any artifact
forgeplan reason <ID>

Workaround

Switch to a provider that talks HTTP directly (claude + ANTHROPIC_API_KEY, gemini, openai). That reintroduces the separate API key and billing that #382 set out to avoid.

Environment

forgeplan	0.34.0 and 0.37.0 — identical failure on both
claude CLI	2.1.266
OS	macOS 25.5.0 (arm64)

Fix

PR follows: unwrap the array to its last type: "result" event before decoding, keep the bare-object path for older CLI versions, and make "array with no result event" a named error instead of a positional mis-parse.