Hopper Debugger

Hopper Debugger

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

Quick Start

Validate the MCP server:

MCPORTER_LIST_TIMEOUT=15000 timeout 20 mcporter list hopper --brief

List open Hopper documents:

MCPORTER_CALL_TIMEOUT=20000 timeout 30 mcporter call hopper.list_documents --output json

If no document is open, open the binary/framework in Hopper first:

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

Hopper may show a first-open/import dialog. Let the user click the confirmation button, then retry the MCP call. Avoid parallel Hopper MCP calls; the server can close the transport or crash Hopper while import is still settling.

Apple Frameworks

Prefer already extracted dyld-cache framework binaries when present:

/tmp/dsc-appkit/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit
/tmp/dsc-appkit/System/Library/Frameworks/SwiftUI.framework/Versions/A/SwiftUI

Open one at a time when debugging SwiftUI/AppKit boundary issues:

open -a "Hopper Disassembler" /tmp/dsc-appkit/System/Library/Frameworks/AppKit.framework/Versions/C/AppKit
mcporter call hopper.list_documents --output json

open -a "Hopper Disassembler" /tmp/dsc-appkit/System/Library/Frameworks/SwiftUI.framework/Versions/A/SwiftUI
mcporter call hopper.list_documents --output json

Verify access:

mcporter call hopper.list_documents --output json
mcporter call hopper.current_document --output json
mcporter call hopper.search_strings pattern=SwiftUI --output json
mcporter call hopper.search_strings pattern=NSStatusItem --output json

Document names can start as Untitled; retry after Hopper finishes importing. Use current_document, symbol/string searches, and window title changes to identify AppKit vs SwiftUI.

Query Workflow

1. Start from the local source path or runtime symbol you are trying to explain. 2. Search names/procedures/strings:

mcporter call hopper.search_procedures pattern='NSStatusBar' --output json
mcporter call hopper.search_name pattern='NSStatusBarButtonCell' --output json
mcporter call hopper.search_strings pattern='NSStatusItem' --output json

3. Inspect one small target at a time:

mcporter call hopper.procedure_info procedure='<symbol>' --output json
mcporter call hopper.procedure_assembly procedure='<symbol>' --output json
mcporter call hopper.procedure_pseudo_code procedure='<symbol>' --output json
mcporter call hopper.procedure_callers procedure='<symbol>' --output json
mcporter call hopper.procedure_callees procedure='<symbol>' --output json
mcporter call hopper.xrefs address=0x12345678 --output json

4. Summarize the relevant control flow; do not paste large decompilations. 5. Validate the hypothesis with LLDB/logging/repro before editing app code.

Status Item / Menu Click Bugs

Useful AppKit/SwiftUI searches:

mcporter call hopper.search_strings pattern='NSStatusItem_Private_ForSwiftUI' --output json
mcporter call hopper.search_procedures pattern='popUpStatusBarMenu' --output json
mcporter call hopper.search_procedures pattern='trackMouse' --output json
mcporter call hopper.search_name pattern='NSStatusBarButtonCell' --output json
mcporter call hopper.search_name pattern='NSStatusItem' --output json

Symbols worth inspecting when menu bar clicks do nothing:

• -[NSStatusBarButtonCell trackMouse:inRect:ofView:untilMouseUp:]
• -[NSStatusBarButtonCell _sendActionFrom:]
• -[NSStatusItem popUpStatusBarMenu:]
• -[NSApplication sendAction:to:from:]
• SwiftUI status/menu symbols that reference NSStatusItem_Private_ForSwiftUI

Compare disassembly against runtime state:

pgrep -af "App.app/Contents/MacOS/App"
lldb /path/to/debug/Binary

For hardened signed apps, attach may fail without get-task-allow; launch the raw debug binary under LLDB when needed.

Failure Handling

• Wrap Hopper calls with timeout; a modal/import or closed document can leave the transport stuck.
• Do not send concurrent Hopper MCP requests during import. If a query is expensive, wait for it to finish before starting another.
• If calls report Connection closed, check for a Hopper modal, then retry after confirmation.
• If Hopper crashes, reopen a single document, wait for import/analysis, and re-run list_documents before deeper searches.
• If mcporter is wedged, inspect processes before killing anything:

pgrep -af 'mcporter|HopperMCPServer|Hopper Disassembler'

• Prefer restarting the mcporter daemon over broad process kills:

mcporter daemon stop
mcporter daemon start