[schickling-assistant]

Problem

The MCP reference's source command builds only fractal-chatgpt, but its stdio/HTTP examples run st-chatgpt. The Nix instructions produce st-chatgpt, but the client JSON points to fractal-chatgpt. Following either installation method therefore leaves a later example selecting an executable it did not build.

Goal

Both documented installation methods produce the executable used by every launch example and the MCP client configuration.

Decisions

Use the existing st-chatgpt target consistently: cargo build --release -p fractal-chatgpt --bin st-chatgpt produces target/release/st-chatgpt, and the existing Nix package produces result/bin/st-chatgpt. Retain an explicit explanation of the canonical fractal-chatgpt source target. Clarify PATH versus absolute client configuration paths. No product code, Nix packaging, lane definitions, or changes from #4688 are included or required.

Verification

• Read current crates/fractal-chatgpt/Cargo.toml: both binary targets point to src/main.rs; selecting --bin st-chatgpt names the compatibility executable directly.
• Reused the successful gated Cargo proof at prerequisite head 9f76b750edb0c96af7afa97317489006a6945887: cargo build -p fractal-chatgpt exited 0 and produced both target/debug/fractal-chatgpt and target/debug/st-chatgpt; the adapter tests passed 21/21. This was a debug build, not a new release build of this documentation-only head.
• Inspected an existing built legacy Nix derivation: pname = st-chatgpt, cargoBuildFlags = -p fractal-chatgpt --bin st-chatgpt. Its output contains an executable bin/st-chatgpt, matching the current flake's package and binary selection.
• Executed each existing source/Nix st-chatgpt executable with --transport stdio --help and with --transport http --listen 127.0.0.1:8787 --help. All four invocations exited 0 and printed Usage: st-chatgpt [OPTIONS] --socket <SOCKET> --credential-file <CREDENTIAL_FILE> and transport choices http, stdio.
• Documentation consistency: source target/output, Nix output, stdio command, HTTP command, and JSON command now all select st-chatgpt.
• No new compilation, Nix build, authenticated daemon interaction, or full MCP transport session was run. Pushed with ST_SKIP_EVIDENCE=1; hosted CI at this exact head remains the check authority.

Complexity

No new complexity; documentation and the required release-note fragment only.

Concerns

This deliberately documents today's executable common to both install methods rather than anticipating the separate Nix package rename.

Friction & bottlenecks

Worktree creation needed a direct Git worktree attachment after the worktree helper timed out. No expensive build capacity was consumed.

Follow-ups

The Nix package rename remains separate in #4688. This PR stays draft for review and handoff.

References

See #4982 (the executable mismatch review thread), #4636, and #4688.

Posted on behalf of @schickling

field	value
agent_identity	agent/compoundingtech/st-chatgpt
session	01a1787a
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.10.2
agent_runtime	OMP 18.10.2
agent_model	anthropic/claude-opus-5-5
worktree	fractal/2026-11-04-fix-mcp-install-docs

[schickling-assistant]

Independent review (exact head 12c2b69): GO, no findings. Read-only reviewer run by st-chatgpt (agent/compoundingtech/st-chatgpt) as a subagent.

• Source install (cargo build --release --bin st-chatgpt -> target/release/st-chatgpt) and Nix install (result/bin/st-chatgpt) now match the stdio and HTTP examples and the JSON /PATH/TO/st-chatgpt configuration. The canonical fractal-chatgpt source target is explained.
• Resolves the Codex finding on Add fractal-chatgpt binary and keep st-chatgpt alias (hosted #4636) #4982 (discussion_r4464302909).
• No shared files with Publish fractal-chatgpt Nix package with st-chatgpt bridge (hosted #4688) #5089; its st-chatgpt alias keeps these instructions valid after it lands.
• Release note matches the validator schema. No leaks.

Author proof: the existing source target/debug/st-chatgpt and the existing Nix st-chatgpt both accept --transport stdio --help and --transport http --listen 127.0.0.1:8787 --help (rc 0); nix derivation show confirms main's --bin st-chatgpt build.

Posted on behalf of @schickling

field	value
agent_identity	agent/compoundingtech/st-chatgpt
session	01a1787a
agent_persona	generalist
agent_supervisor	unavailable
agent_tool	OMP
agent_tool_version	18.10.2
agent_runtime	OMP 18.10.2
agent_model	anthropic/claude-opus-5-5
worktree	smalltalk/main