memorydetective
memorydetective is an MCP server for diagnosing iOS memory leaks, retain cycles, and performance issues — no Xcode required.
Leak detection & analysis — run
leaks(1)against.memgraphfiles to find ROOT CYCLEs, retain chains, and class instance countsCycle classification — match cycles against a catalog of known antipatterns (SwiftUI, Combine, UIKit, Task, NotificationCenter, etc.) with confidence scores and fix hints
Retain cycle tools — find who keeps a class alive (
findRetainers), filter cycles by class, count reachable instances from a cycle root, and render cycles as Mermaid/Graphviz diagramsMemory snapshot diffing — compare two
.memgraphsnapshots to see which cycles appeared, disappeared, or persisted, and verify fixes reduced instance counts and freed bytesTime Profiler trace analysis — parse
.tracebundles for main-thread hangs, animation hitches, allocations, app launch phase breakdown, and top CPU symbolsPerformance regression verification — compare before/after
.tracebundles for hangs, hitches, or launch times with PASS/FAIL thresholdsCapture & record — snapshot live
.memgraphfrom running processes and record Time Profiler traces from simulators or devicesProduction diagnostics — ingest Apple MetricKit
.mxdiagnosticpayloads from TestFlight/App Store with crash clustering and hang hotspot analysisSwift source bridging — locate symbol declarations, find references, get hover type info, and regex-search Swift files via SourceKit-LSP to connect leaks to code
CI integration — run leak detection in XCUITest/XCTest suites with HTML reports, pass/fail gates, and allowlists
Log analysis — query and stream macOS unified logs with NSPredicate filters
Investigation playbooks — retrieve canonical step-by-step tool sequences for memgraph-leak, perf-hangs, UI jank, app-launch-slow, or verify-fix workflows
Diagnoses retain cycles and performance regressions in iOS applications using memory graph and time profile analysis.
Diagnoses retain cycles and performance regressions in macOS applications, including simulator and Mac apps.
Provides tools for searching Swift source code patterns, finding symbol definitions, and locating references within a project.
Analyzes .memgraph files and .trace bundles produced by Xcode to diagnose retain cycles and performance regressions in iOS and macOS apps.
memorydetective
Diagnose iOS retain cycles and performance regressions from your chat window. No Xcode required.

Highlights
CLI-driven leak hunting. Read
.memgraphfiles captured by Xcode (or bymemorydetectiveitself on simulators), find ROOT CYCLEs, classify them against known SwiftUI/Combine patterns, and get a one-liner fix hint. All from a script or a chat.MCP-native. Plugs into Claude Code, Claude Desktop, Cursor, Cline, and any other MCP client. The agent drives the full investigate → classify → suggest-fix loop without you opening Instruments.
Honest about its limits. No mocked outputs, no over-promises. Hangs analysis works clean from
xctrace; sample-level Time Profile is parsed whenxctracesymbolicates the trace and returns a structured workaround notice when it can't (the underlyingxctraceSIGSEGV on heavy unsymbolicated traces is an Apple-side limitation we surface explicitly). Memory Graph capture works on Mac apps and iOS simulator; physical iOS devices still need Xcode.
What's new in v1.18 (2026-05-17): MetricKit + audit-close.
analyzeMetricKitPayloadis the 42nd MCP tool: ingests Apple MetricKit.mxdiagnosticJSON payloads from real-device TestFlight / App Store builds (post-mortem production diagnostics — no MCP competitor covers this lane today). Three actionable outputs: crash clusters by exception type / binary / top frame, hang hotspots with localized-duration parsing ("5.4 sec"/"20秒"), CPU + disk exceptions. Cross-tool chain hints (e.g.objc_release-style top frame surfaces afindCyclessuggestion). Plus three audit-close items: open-enumSupportStatusKind(downstream consumers add kinds without a breaking type bump), invocation-scopedschemaDiscoverycache (summarizeTraceend-to-end shaved from ~28s to ~15s on real Apple traces via single up-front TOC fetch), and local-only integration tests against real Apple.tracebundles (closes the v1.14 P+O drift class for good). 701 → 757 tests. 41 → 42 MCP tools.Also recent (v1.17): reliability pass. 14 bug fixes across three tiers. Headlines: strtobool env truthy parsing,
verifyFixwhitelist match modes (exact / substring / regex),recordViaInstrumentsAppcatches traces saved outsidewatchDir,inspectTracefault-tolerant fallback, configurablecountAliveframework-noise filter, variable-size class min/max/median.And v1.16: macOS 26.x recording-unblock release. New
recordViaInstrumentsAppMCP tool wraps the Instruments.app GUI flow: opens the app, surfaces step-by-step instructions, watches a directory for the saved.trace, and chains intoinspectTraceon success. Until Apple fixes thexcrun xctrace recordregression on macOS 26.x sims, this is the automated path.And v1.15: schema coverage + verify-fix UX. Three new MCP trace tools filled the remaining schema gap:
analyzeMemoryFootprint(38th, VM resident / dirty / virtual + jetsam diagnosis),analyzeEnergyImpact(39th, battery drain investigation),analyzeLeakTimeline(40th, xctrace's leaks instrument as a time series).summarizeTracenow chainsanalyzeNetworkActivity.replayScenariocaptures simulator screenshots per step.Earlier: v1.14 trace-side reliability,
analyzeNetworkActivity, unifiedsupportStatus[], FLEX-inspiredcountAlivesize view, MLeaksFinder + DebugSwift-inspiredverifyFixwhitelist. v1.13 shippedsummarizeTrace+/summarize-traceMCP prompt. v1.12 completed reference-tree propagation. v1.11 added inspectTrace, diffMemgraphs reference-tree. v1.9 shipped analyzeAbandonedMemory, detectLeaksInXCTest, cleanupTraces, mainThreadViolations. Full notes in CHANGELOG.
Heads up for macOS 26.x users: Apple shipped a
task_for_pidkernel regression on macOS 26.x that blocksleaks --outputGraph,heap, ANDxctrace --template Allocationsagainst iOS simulator processes regardless ofMallocStackLogging. Even Xcode's "View Memory Graph Hierarchy" hits it unlessMalloc Stack Loggingis enabled in the scheme's Diagnostics tab. memorydetective surfaces this as a proactiveplatformAdvisoryon the first capture-class tool call, plus aworkaroundNoticewithissue: "macos-26-task-for-pid-broken"ifleaksis invoked. The most reliable workaround today is to target an iOS 18 simulator runtime (install via Xcode > Settings > Platforms > +iOS 18.x). Empirically validated in the notelet investigation 2026-05-12 where three independent CLI memory-introspection paths all failed before iOS 18 was identified as the working escape hatch. SetMEMORYDETECTIVE_SUPPRESS_PLATFORM_ADVISORY=1to silence the notice once you have settled on a workaround.
Also on macOS 26.x:
xctrace recordis broken for simulator targets. Independent from thetask_for_pidregression above,xcrun xctrace record --time-limit Nsagainst iOS simulator processes wedges past the time limit, eventually exits when killed, and the resulting.tracebundle is missing template metadata.xctrace export --tocthen fails withDocument Missing Template Error. Re-validated against Xcode 26.5 (build 17F42, xctrace 16.0) 2026-05-15: regression survives the update. This hits the entirexctrace-based ecosystem the same way (memorydetective.recordTimeProfile, XcodeTraceMCP, and nakedxcrun xctrace recordcalls all fail identically). Workarounds: (1) userecordViaInstrumentsApp(v1.16, hardened in v1.17), which opens Instruments.app for you, prompts you to record + save the.trace, then chains intoinspectTraceautomatically once the bundle appears. v1.17 also catches saves outside the watch directory via an Instruments.app AppleScript document query, returningsavedOutsideWatchDir: trueplus the actual path; (2) record from an older macOS host with Xcode 26.0 if you have one; (3) record against a physical device (the regression appears to be simulator-specific). v1.17 added a viability probe onrecordTimeProfile(bundleStatus: "wedged"when the on-disk bundle is the 52K stub) and oninspectTrace(returnsok: truewith diagnosis text instead of throwing). USAGE.md > Troubleshooting has a step-by-step.
Quickstart
npm install -g memorydetectiveAdd to your MCP client config (Claude Code shown):
// ~/.claude/settings.json
{
"mcpServers": {
"memorydetective": { "command": "memorydetective" }
}
}Or use it directly from the command line:
memorydetective analyze ~/Desktop/myapp.memgraph
memorydetective classify ~/Desktop/myapp.memgraph→ See Examples for chat-driven flows · API for the full tool reference · Configure for Claude Desktop / Cursor / Cline · USAGE.md for the full walkthrough including how fixes flow from diagnosis to your codebase.
Examples
Realistic chat snippets. The agent calls the MCP tools listed in API.
Diagnose a leak from a memgraph
You: I just exported a memory graph at
~/Desktop/example.memgraph. Something's leaking after I close a detail screen. What is it?Claude: (calls
analyzeMemgraph→classifyCycle) Found 4 ROOT CYCLE blocks across 60,436 leaks. The dominant one matches swiftui.tag-index-projection with high confidence. A closure attached via.tag()on a photo carouselForEachis capturingselfstrongly through_viewModel.wrappedValue, which keepsDetailViewModeland the navigation coordinator alive after dismissal.Suggested fix: replace
[weak self]capture in the tap handler with a static helper, or weak-capture the view-model via[weak coord = self.coordinator]. Want me to find the exact file?
Verify a fix actually worked
You: I shipped the fix. Compare
~/Desktop/before.memgraphto~/Desktop/after.memgraphand tell me whetherDetailViewModelcount dropped.Claude: (calls
diffMemgraphs→countAlive)DetailViewModel: 12 → 0 (delta-12). Theswiftui.tag-index-projectioncycle is gone. Total leak count fell from 60,436 to 55,576 (−4,860). Three other ROOT CYCLEs persist. They're SwiftUI internals, not your code.
Self-contained verify-fix loop (v1.8)
When leaks --outputGraph fails on macOS 26.x (Failed to get DYLD info for task), the cause is usually that the app was not launched with MallocStackLogging=1. The new orchestration tools handle this end to end without you wiring up xcodebuild + simctl + axe yourself.
You: Reproduce the leak in
MyAppfor me. Build, launch with the right env vars, repeat the photo carousel flow 5 times to amplify it, capture before, then I'll ship the fix and you capture after.Claude: (calls
bootAndLaunchForLeakInvestigation) Built + booted iPhone 15 (UDIDABCD-...). LaunchedMyApp(PID49581) withMallocStackLogging=1. Bundle idcom.example.MyApp.(calls
replayScenariowith 5 taps on the carousel + back-button cycle, repeat 5) Executed 25 actions in 12.3s. No failures.(calls
captureScenarioState({label:"before"})) Wrotebefore.memgraph(63,201 leaks),before.png,before.ui.json.MallocStackLoggingactive, no workaroundNotice.(you ship the fix and rebuild)
(calls
bootAndLaunchForLeakInvestigation+ replay +captureScenarioState({label:"after"}))(calls
diffMemgraphs→verifyFix)DetailViewModel: 15 → 0.swiftui.tag-index-projectionPASS. Bytes freed: 28.4 MB.
Find the slow path on a real device
You: Profile DemoApp on my iPhone for 90 seconds and tell me where the hangs are.
Claude: (calls
listTraceDevices→recordTimeProfile→analyzeHangs) Recorded~/Desktop/run.trace(90s, attached to DemoApp on iPhone 17 Pro Max). Found 23 user-visible hangs (>500 ms each), longest 1.16 s, average 769 ms. Severe load. All on the main thread. Sample-level hotspots aren't symbolicated yet; open the trace in Instruments for that step (analyzeTimeProfilereturns a structured workaround notice whenxctracecan't symbolicate. See CHANGELOG known limits).
Analyze MetricKit payloads from real-user crashes (v1.18)
You: I have a folder of
.mxdiagnosticfiles from the last 30 days of TestFlight at~/Downloads/metrickit-may/. What's catching real users?Claude: (calls
analyzeMetricKitPayload({ payloadDir: "~/Downloads/metrickit-may/" })) 47 payloads, 2026-04-15 → 2026-05-15. Top: 18 crashes EXC_BAD_ACCESS clustered on the same top frame, all in builds 456 and 457 (clean on 458 + earlier). Pattern matches retain-cycle release — chain hint surfacesfindCyclesnext.Second: 5.4s hang on
libsqlite3.dylib(3 samples). Patterndb-lock. If you reproduce locally, chain intoanalyzeHangswithincludeStackClassification: truefor themainThreadViolations[]classifier.No symbolicated frames in v1.18 (raw
binaryUUID + offsetshipped — dSYM lookup is a separate tool, future release). Localized hang strings handled: input was"5.4 sec", normalized to 5400ms; one diagnostic carried"20秒"(Japanese), normalized to 20000ms.
See USAGE.md § MetricKit production post-mortem for the full end-to-end including how to wire analyzeMetricKitPayload into a verify-fix loop across multiple TestFlight builds.
End-to-end: leak → file → fix suggestion
The full loop, from artifact to code edit. Combines memory-graph analysis with Swift source-bridging.
You: Tem um leak. Memgraph em
~/Desktop/example-leaks.memgraph. The cycle points atDetailViewModel. Find where it lives in the project~/Development/myapp/and suggest a fix.Claude: (calls
analyzeMemgraph→classifyCycle→reachableFromCycle) Found 4 ROOT CYCLE blocks. The dominant one matchesswiftui.tag-index-projectionwith high confidence.reachableFromCycleconfirms 4DetailViewModelinstances pinning ~1100NSURLSessionConfigurations each. The VM is the culprit, the network stack is collateral.(calls
swiftSearchPatternto locate.tag(+onImageSliderTappatterns in~/Development/myapp/Sources/) 1 match inMyApp/Views/MediaCarousel.swift:142.(calls
swiftGetSymbolDefinition({ symbolName: "DetailViewModel", projectRoot: "...", candidatePaths: ["MyApp/ViewModels/"] })) Declared atMyApp/ViewModels/DetailViewModel.swift:18.class DetailViewModel: ObservableObject.(calls
swiftFindSymbolReferencesto scope the blast radius. 7 callsites)Suggested fix at
MediaCarousel.swift:142:// before .tag(index) .onImageSliderTap { index in self.viewModel.handlePhotoTap(at: index) } // after. Static helper + weak captures .tag(index) .onImageSliderTap { [weak vm = _viewModel.wrappedValue, weak coord = self.coordinator] index in Self.handlePhotoTap(index: index, viewModel: vm, coordinator: coord) }Want me to apply this and verify with a fresh
.memgraph?
What it saves you
The pitch in one sentence: memorydetective turns a 50–500 MB binary memgraph (or a 200 KB leaks(1) text dump) into a 2–5 KB structured summary your AI agent can actually reason about. That changes the economics of using an LLM for iOS perf investigation.
Tokens (when paired with an AI agent like Claude / Cursor / Cline)
A real-world retain-cycle investigation, run twice. Once with memorydetective, once with the agent reading the raw leaks(1) output directly:
Step | Without MCP (agent reads raw output) | With |
Load | ~70,000 input tokens | n/a |
| n/a | ~750 input tokens |
| agent re-reasons over the dump per follow-up (3–4 extra turns) | 1 turn, structured |
| agent re-scans the dump | ~500 tokens, scoped query |
Net per investigation | ~85,000 tokens, ~6 turns | ~3,000 tokens, ~2 turns |
Translates to roughly $0.40–$1.20 per investigation depending on the model (Claude Opus / Sonnet / Haiku). Compounds linearly with file size and investigation depth.
Developer time
The same investigation, measured by the developer:
Step | Without MCP | With |
Capture memgraph + run | 5 min | 5 min (same) |
Read & interpret | 15–30 min (skim 200 KB of repetitive frames) | 30 sec (read 3 KB summary) |
Identify the responsible pattern | 10–20 min (recognize the cycle shape from experience) | instant (classifier returns |
Locate the suspect type in source | 10–15 min (grep + manual navigation) | 30 sec ( |
Find every callsite to gauge fix blast radius | 5–10 min (Xcode / grep) | 10 sec ( |
Net wall-clock | 45–80 min | ~10 min |
Numbers are rounded from a single anonymized real investigation (a SwiftUI retain cycle over a tagged ForEach that pinned ~28 MB of network-stack state). Your mileage will vary with cycle complexity and codebase size.
When the win is marginal
Be honest about where this doesn't help much:
Tiny memgraphs (a single cycle, < 50 KB raw): MCP overhead is roughly token-neutral vs. Raw read. The dev-time win still holds (no manual cycle parsing) but the token win shrinks.
One-shot symbol lookups without a leak attached: just use
grep, you don't need this.First-time investigations on a new codebase: the agent still needs orientation turns regardless of MCP. The compounding wins kick in on the second and later investigations once the agent has cached the project's shape.
The win compounds with (a) file size, (b) investigation depth (multi-turn), and (c) how many leaks you investigate per quarter. For a single dev fixing one leak per year, the value is mostly the dev-time saving. For a team running CI gates with verifyFix across every PR, the token + time savings stack across hundreds of runs.
Configure
The memorydetective binary speaks MCP over stdio. Point any MCP-compatible client at it.
// ~/.claude/settings.json (global) or .mcp.json (per-project)
{
"mcpServers": {
"memorydetective": { "command": "memorydetective" }
}
}// ~/Library/Application Support/Claude/claude_desktop_config.json
{
"mcpServers": {
"memorydetective": { "command": "memorydetective" }
}
}Restart Claude Desktop after editing.
// ~/.cursor/mcp.json
{
"mcpServers": {
"memorydetective": { "command": "memorydetective" }
}
}// VS Code settings.json
{
"cline.mcpServers": {
"memorydetective": { "command": "memorydetective" }
}
}Kiro supports MCP servers via its global config. The block mirrors Claude Desktop's:
{
"mcpServers": {
"memorydetective": { "command": "memorydetective" }
}
}Consult Kiro's MCP setup docs for the exact config file path on your system.
GitHub Copilot supports MCP servers in Agent mode (VS Code 1.94+). Add to .vscode/mcp.json in your repo:
{
"servers": {
"memorydetective": {
"type": "stdio",
"command": "memorydetective"
}
}
}Copilot's MCP integration moves fast. If this snippet is stale, see the VS Code MCP docs.
Environment variables
Every boolean MEMORYDETECTIVE_* flag below accepts the strtobool truthy set (case-insensitive): 1 / true / t / yes / y / on (truthy) and 0 / false / f / no / n / off (falsy). Unrecognized values emit a one-time stderr warning per variable and fall back to the documented default. Pre-v1.17 the parser was 1-only, which caused silent no-ops when operators exported =true or =yes. The advisory warning is gated on MEMORYDETECTIVE_SUPPRESS_PLATFORM_ADVISORY.
Variable | Default | Effect |
|
| Output scrubbing applied to every tool response. |
| unset | Boolean (strtobool). Allows |
|
| Cap on |
|
| Directory used when |
| unset | Boolean (strtobool). Allows |
| unset | Boolean (strtobool). Silences the macOS 26.x platform advisory that captureMemgraph, captureScenarioState, and bootAndLaunchForLeakInvestigation emit on first use. Also silences the v1.17 stderr warnings emitted on unrecognized boolean values (any |
| unset | Boolean (strtobool). Makes |
| unset (auto) | Boolean (strtobool) + |
API
36 MCP tools + 34 Resources + 6 Prompts, grouped by purpose. Tool descriptions are tagged with a category prefix ([mg.memory], [mg.trace], [mg.build], [mg.scenario], [mg.code], [mg.log], [mg.render], [mg.ci], [mg.discover], [ops], [meta]) so related tools are visible at a glance.
Many tools include a suggestedNextCalls field in their response. A typed list of { tool, args, why } entries pre-populated from the current result, so the orchestrating LLM can chain calls without re-reasoning. Start with getInvestigationPlaybook(kind) for the canonical sequence. Or just type /investigate-leak (one of the Prompts) in any client that exposes MCP slash commands.
The cycle classifier ships 36 named antipatterns spanning SwiftUI (including the Swift 6 / @Observable / SwiftData / NavigationStack era, plus the v1.9 swiftui.observable-write-on-every-render shape), Combine, Swift Concurrency (incl. AsyncSequence-on-self and the new Observations API), UIKit (Timer/CADisplayLink/UIGestureRecognizer/KVO/URLSession/WebKit/DispatchSource, plus the v1.9 uikit.viewcontroller-retained-after-pop shape), Core Animation, Core Data, Coordinator pattern, and the popular third-party libs RxSwift + Realm. Each pattern carries:
a textual one-line
fixHinta confidence tier (
high/medium/low)a
staticAnalysisHintpointing at the SwiftLint rule that complements the runtime evidence (or an explicit gap notice when no rule exists. Reinforces the differentiator: memorydetective sees what linters miss at parse time)a
fixTemplatewith concrete Swift before/after snippets (new in v1.7) the agent can adapt directly to the user's code via the SourceKit-LSP source-bridging tools
Read & analyze (14)
All 9 trace-side analyzers below accept an optional second argument
AnalyzeTraceOptions(v1.18 D-02). When called bysummarizeTrace(which runs schema discovery once up front), the cache is forwarded so the per-analyzerxctrace --toccalls are skipped. Direct callers leave the option unset and behavior is identical to v1.17.
Tool | What |
| Run |
| Extract just the ROOT CYCLE blocks as flattened chains, with optional |
| "Who is keeping |
| Count instances by class. Provide |
| Cycle-scoped reachability. "How many |
| Compare two |
| Diff two |
| Cycle-semantic diff: per-pattern PASS/PARTIAL/FAIL verdict + bytes freed. CI-gateable. |
| Match each ROOT CYCLE against a built-in catalog of 36 named antipatterns (SwiftUI / Combine / Concurrency / UIKit / Core Animation / Core Data / Coordinator / RxSwift / Realm) with confidence + textual |
| Parse |
| Parse |
| Parse |
| Parse |
| Parse |
| One-shot query of macOS unified logging via |
Capture / record (4)
Tool | What | Sim | Device |
| Wrap | ✅ | ✅ |
| macOS 26.x escape hatch (v1.16). Opens Instruments.app via | ✅ | ✅ |
| Wrap | ✅ | ❌. Use Xcode |
| Wrap | n/a | n/a |
Verify-fix orchestration (3, v1.8)
These three tools combine into a single deterministic verify-fix loop: launch the app with MallocStackLogging=1 so leaks works, drive the UI to amplify the suspected leak, snapshot before, ship the fix, snapshot after, then diffMemgraphs.
Tool | What |
| Single-call build + boot + install + launch with |
| Drive the iOS Simulator through tap / swipe / wait / type actions with a |
| Composite snapshot for verify-fix: writes |
Discover (3)
Tool | What |
| Parse |
| Parse |
| Orientation tool for |
Synthesize (1)
Tool | What |
| Single call that chains |
Production diagnostics (1, v1.18)
Tool | What |
| Ingest Apple MetricKit |
Render (1)
Tool | What |
| Read a |
Ops (1)
Tool | What |
| Preview and delete |
CI / test integration (3)
Tool | What |
| Build the unit-test scheme, run with an optional |
| XCUITest sibling: build the workspace, run the named XCUITest, capture |
| Trace-side counterpart to |
Add memorydetective to your CI in 5 minutes
detectLeaksInXCTest + outputHtmlPath are the building blocks for a per-PR leak gate. The job below runs the named unit-test scheme on every push and PR, uploads the HTML report as a workflow artifact, and fails when new ROOT CYCLEs appear outside the allowlist. Copy the file into .github/workflows/leaks.yml and adjust the workspace + scheme + test identifier:
name: leaks
on: [push, pull_request]
jobs:
detect-leaks:
runs-on: macos-14
timeout-minutes: 30
steps:
- uses: actions/checkout@v4
- run: sudo xcode-select -s /Applications/Xcode_15.4.app
- run: npm install -g memorydetective
- run: |
xcrun simctl boot "iPhone 15" || true
xcrun simctl bootstatus "iPhone 15" -b
- run: |
cat > leaks.json <<EOF
{
"workspace": "DemoApp.xcworkspace",
"scheme": "DemoAppTests",
"destination": "platform=iOS Simulator,name=iPhone 15,OS=18.0",
"testCaseFilter": "DemoTests/LeakSensitiveCase",
"outputHtmlPath": "${GITHUB_WORKSPACE}/leak-report.html",
"allowlistPatterns": ["SwiftUI", "_TtC"]
}
EOF
memorydetective tool detectLeaksInXCTest --input leaks.json
- if: always()
uses: actions/upload-artifact@v4
with:
name: leak-report
path: leak-report.html
retention-days: 14The same file is in examples/ci/github-actions-leaks.yml if you want to copy it verbatim. Notes:
Simulator runtime: pin to iOS 18 on
macos-14runners. The macOS 26.x kernel regression (task_for_pid) breaksleaksagainst iOS 26 sims; iOS 18 is the canonical escape hatch (see the Highlights callout above).Allowlist patterns: substrings matched against the leaking ROOT CYCLE's root class. Use them to mask known pre-existing leaks while you work the backlog.
_TtCcovers Swift mangled class prefixes that occasionally show up in SwiftUI internals.HTML artifact: the report is self-contained (inline CSS, no external assets), so PR-comment bots and reviewers can preview it directly from the artifact URL.
Build cache: add
actions/cache@v4keyed onPackage.resolved+*.xcconfigto skipbuild-for-testingrebuilds across runs. Then pass--skipBuildto the second invocation when chaining multipledetectLeaksInXCTestcalls on the same job.
Swift source bridging (5)
Pair the memory-graph diagnosis with source-code lookups via SourceKit-LSP. Closes the loop "found this leak in the cycle → find the file/line in your project".
Tool | What |
| Locate the file:line where a Swift symbol is declared. Pre-scans |
| Find every reference to a Swift symbol via SourceKit-LSP |
| List top-level symbols (classes, structs, enums, protocols, free functions) in a Swift file via |
| Type info / docs at a (line, character) position. Disambiguates |
| Pure regex search over a Swift file (no LSP, no index). Catches what LSP misses: closure capture lists, |
These tools require macOS + Xcode (full Xcode, not just Command Line Tools. xcrun sourcekit-lsp must be available). They start a sourcekit-lsp subprocess per project root and reuse it across calls; the subprocess shuts down after a 5-minute idle window.
Why
captureMemgraphdoesn't work on physical iOS devices:leaks(1)only attaches to processes running on the local Mac (which includes iOS simulators). Memory Graph capture from a real device goes through Xcode's debugger over USB/lockdownd. Different mechanism, no public CLI equivalent.
Resources (34)
The cycle-pattern catalog is also surfaced as MCP resources, browsable at memorydetective://patterns/{patternId}. Each resource is a markdown body with the pattern name, a longer description, and the fix hint. Use this to let an agent (or a human in a UI-aware MCP client) browse the catalog without burning a classifyCycle call.
memorydetective://patterns/swiftui.tag-index-projection
memorydetective://patterns/concurrency.async-sequence-on-self
memorydetective://patterns/webkit.wkscriptmessagehandler-bridge
memorydetective://patterns/swiftdata.modelcontext-actor-cycle
…resources/list returns all 34 entries. resources/read resolves any memorydetective://patterns/{id} URI to its markdown body.
Prompts (7)
Investigation playbooks are exposed as MCP prompts (slash commands in clients that surface them, e.g. Claude Code).
Slash command | What it does | Args |
| Runs the canonical 6-step memgraph-leak investigation: |
|
| Diagnose user-visible main-thread hangs from a |
|
| Diagnose dropped frames / animation hitches from a |
|
| Diagnose cold/warm launch slowness from a |
|
| Diff a before/after pair of |
|
| Single-call cross-schema summary card for a |
|
| Post-mortem flow for Apple MetricKit |
|
Each prompt fills the canonical playbook's argument templates with the user-provided values, then hands the agent a ready-to-execute brief. Calls the same tools listed in Read & analyze. Prompts are an orchestration shortcut, not a separate engine.
CLI mode
The same binary is also a thin CLI for scripting and CI:
memorydetective analyze <path-to-.memgraph> # totals, ROOT CYCLEs, diagnosis
memorydetective classify <path-to-.memgraph> # match patterns + render fix hint
memorydetective tool <toolName> --input <json> # generic dispatcher for any MCP tool
memorydetective --help
memorydetective --versionWhen called with no arguments, the binary starts as an MCP server over stdio.
The tool subcommand dispatches to any registered MCP tool by name, reading inputs from a JSON file. Exit code is 0 when the tool returns ok && passed !== false, 1 otherwise, so it slots cleanly into CI gates. Currently supported tool names: detectLeaksInXCTest, detectLeaksInXCUITest (the CI recipe above uses this).
Requirements
macOS with Xcode Command Line Tools (
xcode-select --install)Node.js ≥ 20
Develop
git clone https://github.com/carloshpdoc/memorydetective
cd memorydetective
npm install
npm test # 546 unit tests
npm run build # build → dist/
npm run dev # tsx, stdio mode (dev mode)
./scripts/demo.sh # full demo against a real .memgraph (set MEMGRAPH=path)Contributing
Contributions are welcome. Bug reports, feature requests, new cycle patterns, all of it.
Bugs / feature requests: open an issue.
PRs: fork → branch →
npm install→ make changes →npm test(546 tests must stay green) → open a PR with a concise description of what changed and why.
Adding a cycle pattern to classifyCycle
classifyCycle ships with 36 built-in patterns covering SwiftUI (incl. Swift 6 / @Observable / SwiftData / NavigationStack / the v1.9 observable-write-on-every-render and viewcontroller-retained-after-pop shapes), Combine, Swift Concurrency (incl. AsyncSequence-on-self and Observations), UIKit (Timer / CADisplayLink / UIGestureRecognizer / KVO / URLSession / WebKit / DispatchSource), Core Animation, Core Data, the Coordinator pattern, RxSwift, and Realm. To add one:
Edit
src/tools/classifyCycle.ts. Add an entry toPATTERNSwithid,name,fixHint, and amatchfunction.Add a test in
src/tools/readTools.test.tsthat asserts the new pattern fires against a representative memgraph fixture.Add a
staticAnalysisHintentry insrc/runtime/staticAnalysisHints.ts(the test in that file enforces 1:1 coverage withPATTERNS).Add a
fixTemplateentry insrc/runtime/fixTemplates.ts(same 1:1 coverage guard).Open a PR.
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Why "memorydetective"?
Hunting retain cycles in SwiftUI feels like detective work: you have a body (the leaked instance), a crime scene (the .memgraph), and a chain of suspects (the retain chain). The tool helps you read the evidence and name the killer. The brand follows the work.
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