Hopper Debugger

Use Hopper through mcporter as a queryable disassembler, then combine the result with local source, LLDB, logs, and focused repros.

Setup (one time)

Hopper 6.0+ ships its own MCP server. Do not install a third-party one.

mcporter config add hopper --scope home \
  --command "/Applications/Hopper Disassembler.app/Contents/MacOS/HopperMCPServer" \
  --description "Hopper Disassembler built-in MCP server (stdio)"

--scope home is required. The default scope is project, which writes config/mcporter.json into whatever repo you are standing in (untracked repo dirt, lost with the worktree).

Verify:

MCPORTER_LIST_TIMEOUT=25000 timeout 40 mcporter list hopper --brief

Call convention — the one that bites

Always pass arguments with --args. Never --params. mcporter accepts an unknown --params flag silently, drops the payload, and the call arrives with no arguments. Hopper then answers Document not found., which reads like a licensing or state problem and is not.

# WRONG — arguments silently dropped, fails with "Document not found."
mcporter call hopper.list_segments --params '{"document":"AppKit"}'

# RIGHT
mcporter call hopper.list_segments --args '{"document":"AppKit"}'

Related: the server does not fall back to the current document. A call with no document argument fails even when current_document returns a valid name. Pass document on every document-scoped call.

Document names come from list_documents and carry no .hop extension (window title AppKit.hop → document name AppKit).

If a call still fails, drive the server directly over stdio to see the raw JSON-RPC — this bypasses mcporter entirely and isolates who is at fault:

"/Applications/Hopper Disassembler.app/Contents/MacOS/HopperMCPServer" <<'EOF'
{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"p","version":"1"}}}
{"jsonrpc":"2.0","method":"notifications/initialized"}
{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"list_documents","arguments":{}}}
EOF

Licensing — do not misdiagnose

Hopper 6.x still uses the bundle id and preferences domain com.cryptic-apps.hopper-web-4. The absence of a hopper-web-6 domain does not mean the app is unlicensed. Check the real state in the About panel (Hopper Disassembler > About Hopper Disassembler); it prints the licensee, order id, and update-plan expiry. There is no Register/License menu item in Hopper 6.

Peter's license: order HOP140213-7833-95831, updates through 2027-05-17. The .hopperLicense file is in 1Password (Molty vault, document item "Hopper Disassembler License (HOP140213-7833-95831)"); load $one-password to retrieve it. Opening a .hopperLicense file with Hopper does not register it — Hopper disassembles it as a document.

Opening documents

open -a "Hopper Disassembler" /path/to/Binary

Small binaries import with no dialog. Large frameworks take minutes; poll instead of sleeping:

until mcporter call hopper.list_documents --output json 2>/dev/null | grep -qi "appkit"; do sleep 10; done

Dismiss any first-open dialog with an Accessibility press, never a synthetic click — clicking moves Peter's physical pointer:

osascript -e 'tell application "System Events" to tell process "Hopper Disassembler" to perform action "AXPress" of (button 1 of window 1)'

Apple frameworks

Apple frameworks live in the dyld shared cache, not on disk. Two routes:

1. Prefer Peter's pre-made exports at ~/Library/CloudStorage/Dropbox/Hopper/ — .hop documents plus .m pseudo-code dumps for AppKit, AccessibilityKit, and others. Grepping the .m is often faster than any MCP round-trip (AppKit.m is 244 MB).

Check provenance before trusting them for version work. These are snapshots; as of 2026-08 they predate macOS 26.6 and 27.0, and their class/method inventory differs from both live runtimes. Good for structure, unreliable for OS-version diffing.

1. Extract fresh with /usr/lib/dsc_extractor.bundle (present on macOS; extracts all dylibs, multi-GB, slow).

Query workflow

1. Start from the local source path or runtime symbol you are trying to explain.
2. Find the symbol, then inspect one small target at a time:

mcporter call hopper.search_procedures --args '{"document":"AppKit","pattern":"addCursorRect"}' --output json
mcporter call hopper.procedure_pseudo_code --args '{"document":"AppKit","procedure":"0x185475b2c"}' --output json

procedure accepts a symbol name or a hex address. Other useful tools: listdocuments, currentdocument, setcurrentdocument, listsegments, listprocedures, liststrings, searchstrings, procedureinfo, procedureaddress, current_procedure.

1. Summarize the relevant control flow; do not paste large decompilations.
2. Validate the hypothesis with LLDB/logging/repro before editing app code.

Pairing with runtime evidence

Disassembly tells you which store a value lands in; only the runtime tells you whether it got there. Read the pseudo-code first to learn which ivar/collection the API actually writes to, then read that exact store at runtime with classcopyIvarList + objectgetIvar + perform. Instrumenting the wrong (legacy) path is the classic time sink: on modern AppKit, -[NSWindow addCursorRect:cursor:forView:] is dead code, and cursor rects are stored in NSTrackingAreaAKViewHelper's cursorAreas set.

Always run the same probe on a second machine at a different OS version before concluding "regression". Several no-op probes look identical on a known-good OS and a known-broken one; a control run is what tells you the probe is measuring nothing. See $remote-mac for the fleet and codexbar-ui-verification-quirks memory for the cursor-measurement harness.

Failure handling

• Wrap Hopper calls with timeout; a modal or import can leave the transport stuck.
• Do not send concurrent Hopper MCP requests during import.
• Connection closed usually means Hopper is not running or is showing a modal. Check windows via System Events, then retry.
• Document not found. almost always means missing arguments (see --args above), not a broken document.
• If mcporter is wedged, prefer restarting its daemon over broad process kills:

mcporter daemon stop && mcporter daemon start