cordy

Cordy — cross-model consultation

This skill teaches you how to drive cordy for cross-model consultation. It's a capability skill, not a recipe — pick the shape that fits the user's ask.

The thesis

Models from different training lineages have uncorrelated blind spots. A bug Claude misses is often a bug Codex catches. A claim Gemini gets wrong is often one a local Ollama model nails. On any task that rewards multiple perspectives, a panel from different families lifts quality measurably.

Note: cross-model consultation is adversarial sanity-checking, not grounded fact verification. Consensus among LLMs is not truth — it's "these models all agree". For sourced verification you need tools (web search, file reads, etc.) inside the peer's own session, not this skill.

Pre-flight: check cordy + drivers (do this first, every time)

Before any cordy invocation, read the preflight cache. The plugin's SessionStart hook writes the cache to multiple locations — pick the first one that exists:

1. ${CLAUDE_PLUGIN_DATA}/preflight.json — canonical, only set inside the Claude Code harness; may not be exported to Bash subshells, so the env-var probe can return empty even when the file exists.
2. ${XDG_CACHE_HOME}/claude-cordyceps/preflight.json — XDG override.
3. ~/.cache/claude-cordyceps/preflight.json — always written as a shell-accessible mirror; this is the fallback that always works from a Bash subshell on POSIX.

for p in \
  "${CLAUDE_PLUGIN_DATA:+$CLAUDE_PLUGIN_DATA/preflight.json}" \
  "${XDG_CACHE_HOME:+$XDG_CACHE_HOME/claude-cordyceps/preflight.json}" \
  "$HOME/.cache/claude-cordyceps/preflight.json"; do
  [ -n "$p" ] && [ -f "$p" ] && cat "$p" && break
done

If no cache file exists at any of those paths, probe inline: cordy --ephemeral drivers --json. (This means the SessionStart hook either hasn't run yet or failed silently — surface the inline-probe result and proceed.)

Preflight status schema

{
  "schemaVersion": 1,
  "ts": "...",
  "testedRange": "^0.5.2",
  "cordy":   { "installed": true|false, "version": "x.y.z", "execError"?: "..." },
  "drivers": [{ "id": "...", "available": true|false, "compat": "...", "warnings": [...] }],
  "driverProbeError"?: "...",
  "preflightError"?: "..."
}

Decision tree — check fields in this order (first match wins):

State	Tell the user
preflightError set	Preflight itself crashed (<preflightError>). The cordy.installed field is unreliable in this state — surface the message and ask the user to file an issue, then probe inline with cordy --ephemeral drivers --json to recover.
cordy.execError set	Cordy is installed but couldn't be executed (<execError>). Likely a permissions or shell-policy issue; do NOT suggest reinstall.
cordy.installed === false	Cordy not on PATH. Install: npm i -g @ellyseum/cordyceps. Ask permission before running it.
driverProbeError set	Cordy ran but the driver probe failed (<driverProbeError>). Try cordy doctor for a clearer error.
drivers all available: false	No peer drivers reachable. List the README's per-driver setup steps.
Some drivers available	Proceed; build the panel from available: true drivers.

What cordy gives you

cordy is a local daemon plus CLI. Two surfaces:

• High-level subcommands (use these whenever they fit):
  • cordy council review <path> — silo'd file review with chair synthesis. Built-in chunking for files > 30KB.
  • cordy council diff [base] [--staged] [--scope <path>] — same, for git diffs.
• Low-level primitives for everything else:
  • cordy spawn <driver> --name <id> --mode=<mode> [--key=val ...]
  • cordy send <id> "<prompt>" --timeout <s>
  • cordy list / cordy state <id>
  • cordy interrupt <id> (cancel current work)
  • cordy kill <id>

Driver naming — two distinct surfaces

This is easy to get wrong. Different commands accept different driver syntaxes.

Command	Driver argument shape
cordy spawn	bare driver id or alias: claude, claude-code, codex, cx, gemini, gm, ollama, ol. To pick a Claude model, pass --model=opus or --model=sonnet.
cordy council --panel / --chair	comma-separated list of driver or driver:model shorthand: codex,gemini,claude:sonnet,claude:opus.

Don't use claude:opus as the first arg to cordy spawn — that's council-only shorthand and will fail (cordy emits a generic "Internal error" without surfacing the parse failure, so the wrong- syntax cause isn't obvious from the message alone). Use cordy spawn claude --mode=exec --model=opus instead.

cordy spawn flag form is --key=value (with =), per its [--key=val ...] parser. --mode=exec works; --mode exec does not.

Use --mode=exec whenever possible — much cleaner output than PTY, no TUI parsing surprises, faster.

Common shapes (ingredients, not recipes)

Pick what fits the user's ask; combine; deviate as needed.

Shape 1 — Single peer query

One spawn, one send, one kill. For "ask Codex/Gemini what they think about X" with no synthesis needed.

cordy spawn codex --name ask-codex --mode=exec
cordy send ask-codex "<question>" --timeout 300
cordy kill ask-codex

For Claude variants:

cordy spawn claude --name ask-claude --mode=exec --model=opus
cordy send ask-claude "<question>" --timeout 300
cordy kill ask-claude

Shape 2 — Silo'd panel + host-as-chair synthesis

The default for code review, plan critique, design review. Each peer reviews independently (no peer sees another's output); you (the host Claude session) synthesize their findings.

The host has the user's full conversation context, framing, and the panel's outputs all in one place — that's exactly the chair's job. No reason to spawn a separate chair LLM and pay the extra round-trip; read the per-reviewer findings and synthesize them yourself.

For files and git diffs, cordy ships this with --no-chair:

# File review — host as chair
cordy council review <path> \
  --panel codex,gemini,claude:sonnet,claude:opus \
  --no-chair \
  --timeout 600 --json

# Diff review — host as chair
cordy council diff [base] [--staged] [--scope <path>] \
  --panel codex,gemini,claude:opus \
  --no-chair \
  --timeout 600 --json

--no-chair (cordy ≥ 0.5.2) skips the chair-spawn entirely; the result's synthesis field is empty. Read reviews[] and produce the synthesis yourself, then present it to the user.

On cordy < 0.5.2 (no --no-chair): pass --chair codex (or any cheap chair), use --json, IGNORE synthesis/chairError, and synthesize from reviews[] yourself. The wasted chair spawn is unavoidable on older cordy.

When TO let cordy chair (rare): long-running automated runs where the host isn't around to consume per-reviewer JSON, or "give me a single verdict" workflows where the user explicitly wants one model producing the synthesis without your interpretation. Pass --chair codex (or claude:opus) explicitly in those cases.

Note: --panel and --chair accept the driver:model shorthand (claude:opus); cordy spawn does NOT.

For non-file targets (a plan in chat, a design proposal, a decision), do the orchestration manually with the primitives:

PFX=council-$$
PROMPT='Review the following plan. For each finding: severity, what is wrong, what to do about it. Output JSON findings array on the LAST line.

PLAN:
<the user plan>'

# Spawn — note bare driver names + --model=<x> for Claude variants
cordy spawn codex  --name "$PFX-codex"  --mode=exec
cordy spawn gemini --name "$PFX-gemini" --mode=exec
cordy spawn claude --name "$PFX-opus"   --mode=exec --model=opus

# Parallel send
for n in codex gemini opus; do
  ( cordy send "$PFX-$n" "$PROMPT" --timeout 600 > "/tmp/$PFX-$n.txt" 2>&1 ) &
done
wait

# Read each, dedupe, synthesize, present.

# Cleanup
for n in codex gemini opus; do cordy kill "$PFX-$n"; done

Shape 3 — Adversarial pair (for / against)

When the user wants a decision explored from both sides.

cordy spawn codex  --name advocate --mode=exec
cordy spawn gemini --name critic   --mode=exec
( cordy send advocate "Argue FOR <X>. Strongest case." --timeout 300 > /tmp/advocate.txt ) &
( cordy send critic   "Argue AGAINST <X>. Strongest case." --timeout 300 > /tmp/critic.txt ) &
wait
# Read both, synthesize trade-offs.
cordy kill advocate
cordy kill critic

Shape 4 — Divergent brainstorm panel

Same prompt to N peers, no chair — present all responses or cluster them.

PFX=brain-$$
cordy spawn codex  --name "$PFX-codex"  --mode=exec
cordy spawn gemini --name "$PFX-gemini" --mode=exec
cordy spawn claude --name "$PFX-opus"   --mode=exec --model=opus
cordy spawn claude --name "$PFX-sonnet" --mode=exec --model=sonnet
for n in codex gemini opus sonnet; do
  ( cordy send "$PFX-$n" "Brainstorm: <prompt>. Give 5 distinct ideas." --timeout 300 > "/tmp/$PFX-$n.txt" ) &
done
wait
# Cluster + dedupe + present
for n in codex gemini opus sonnet; do cordy kill "$PFX-$n"; done

Shape 5 — Tiered escalation (cheap-first)

For high-volume claim cross-checks. Start cheap (local Ollama); escalate only when uncertain or contested.

cordy spawn ollama --name fc --mode=server-http
cordy send fc "<claim>" --timeout 60
# If confident → done. Otherwise:
cordy spawn codex --name fc-codex --mode=exec
cordy send fc-codex "<claim>" --timeout 180
# Compare; surface disagreement to the user.
cordy kill fc
cordy kill fc-codex

Shape 6 — Persistent sidecar

Spawn once, send multiple times during an iterative session, kill at the end. For "keep a challenger around while I refactor" workflows.

cordy spawn codex --name sidecar --mode=exec
# ... in subsequent turns, as the user iterates ...
cordy send sidecar "<follow-up question>" --timeout 300
cordy interrupt sidecar   # cancel current work if stuck
# ... at end of session ...
cordy kill sidecar

Shape 7 — Meta-review (review-of-review)

Feed one peer's verdict to another peer for evaluation. Highest-signal shape — second-peer critique often surfaces what both you AND the first reviewer missed.

cordy spawn gemini --name meta --mode=exec
cordy send meta "Another LLM reviewed <X> and produced these findings: \
<first peer's verdict>

The <X> being reviewed: <content or path>

Evaluate the first reviewer. For each finding: do you agree, disagree,
partially agree? What did they miss?" --timeout 600
cordy kill meta

Building the invocation

Whichever shape you pick, build flags from the preflight context:

• Panel: pick from drivers where available: true. Aim for cross-family diversity (one of: codex, gemini, ollama; plus one or two Claude variants). Two Claude models is fine when stakes are high — they catch different things despite shared lineage.
• Chair: default to --no-chair and synthesize yourself — you're the chair. Only override (with --chair codex or claude:opus) for the rare "give me one model's verdict without your interpretation" workflow. Avoid Ollama as chair if you do override — synthesis is where local models tend to drop quality.
• Timeout: ~300s for a single peer; 600s for a multi-peer council on a real file or diff; 900s for large content with chunking.
• Mode: --mode=exec for one-shot work (default for council); --mode=server-http for Ollama; --mode=pty only when you need TUI control flow.
• --json on cordy council: structured per-peer output for consumption. Omit to print the chair's verdict directly.

Spawning concurrent peers safely (low-level primitives)

When the high-level subcommands don't fit:

• Unique agent names per task. Prefix with a session-scoped id (PFX=task-$$ or a random hex string) so concurrent invocations don't collide.
• Send in parallel via background subshells + wait (or the Bash tool's run_in_background parameter for proper tracking).
• Always kill spawned agents when done, even on error paths — use a trap or explicit cleanup loop.

Long-running councils — don't poll, don't monitor

Council reviews on real files take 5–15 minutes (per-reviewer model calls run concurrently; total wall-clock = slowest reviewer + chunk synthesis). Run them with the Bash tool's run_in_background: true and write JSON output to a tempfile:

cordy council review <path> --panel <drivers> --no-chair \
  --timeout 600 --json > /tmp/council-$$.json 2>&1

When the background command finishes, the runtime fires a <task-notification> automatically. Do not:

• Set up a Monitor tool stream — there are no intermediate events during a council run; cordy buffers per-reviewer output until all reviewers finish, then writes one JSON blob in one shot.
• Poll the output file with repeated tail / wc -c calls — it stays empty until the slowest reviewer returns, then becomes the full result. Polling burns context for nothing.
• Use sleep loops to "check back" — the auto-notification is the signal.

The right pattern: fire-and-forget background run, do other work or respond to the user, surface findings when the notification lands. If the run hasn't notified in ≳1.5× the panel's max --timeout, something is genuinely stuck — at that point investigate.

Council reviewer modes — Claude defaults to exec (cordy 0.5.3+)

Claude reviewers in council default to exec mode (claude --print) not pty. PTY output parsing was unreliable for headless review use — TUI escape codes and multi-line JSON arrays caused silent reviewer parse-failures, degrading 4-driver panels to 2 drivers in the wild.

If you absolutely need PTY for a Claude reviewer (rare — interactive back-and-forth doesn't fit the council shape), pass an explicit profile via the JSON-RPC method (council.review with { panel: [{ driver: "claude", profile: { mode: "pty" } }] }). The CLI --panel shorthand always uses the default mode.

Failure modes

• Driver auth failure. Cordy emits a clear error; surface it. Tell the user what env var or login command the failing driver needs.
• Timeout. Bump --timeout, shrink the prompt, or use cordy's built-in chunking (in cordy council review).
• Peers disagree. Don't collapse to majority — the minority opinion is often where the real insight is. Surface the disagreement.
• All available drivers same family. Diversity benefit is reduced. Tell the user; offer to proceed or pause to install another driver.

Anti-patterns

• Don't activate on chitchat. "Sounds good" / "that works" are not consult requests.
• Don't activate on ambiguous "second opinion" / "peer review" / "plan review" without a clear cross-model signal AND a target artifact. When in doubt, ask one clarifying question.
• Don't auto-install cordy or any driver CLI without permission.
• Don't write to ~/.cordyceps/ — that's cordy's own state dir. Use ${CLAUDE_PLUGIN_DATA} or ~/.cache/claude-cordyceps/.
• Don't fabricate peer responses. If a peer errored or timed out, say so plainly.
• Don't burn an Ollama call when a faster cloud peer is available unless the user specifically asked for cheap / local.
• Don't re-implement what cordy ships. If cordy council diff exists, use it instead of writing a manual diff-review loop.
• Don't pass claude:opus / claude:sonnet as the driver argument to cordy spawn — that's council-panel shorthand only and will fail. Use bare claude + --model=opus.