audit-xcode-security-settings

name

audit-xcode-security-settings

description

Audit and enable security-oriented Xcode build settings. Progressively enables compiler warnings, static analyzer checkers, and Enhanced Security features. Use when: user wants to secure their Xcode project, audit security settings, enable hardening, review security posture of build configuration, set up security-focused static analysis, enable static analysis, improve warning coverage, harden diagnostics, or catch more bugs at compile time in C/C++/Objective-C/Swift. SKIP: network security (TLS/ATS), code signing, privacy APIs.

Audit Xcode Security Settings

Assess an Xcode project's security posture and progressively enable security build settings and entitlements — from broadly applicable warnings through Enhanced Security hardening.

Tool Preferences

When XcodeGlob, XcodeGrep, XcodeRead, XcodeLS, and XcodeUpdate tools are available, ALWAYS use them. Do not fall back to Bash filesystem tools (ls, find, cat, grep) to learn about the project. They trigger extra permission prompts and bypass project scoping.

Tool names may carry an MCP server prefix. These tools are hosted by an MCP server whose name varies by environment (xcode-mcp, xcode-tools, xcode, etc.), so their fully qualified names look like mcp__<server>__XcodeGlob. Some harnesses register short aliases (just XcodeGlob); others only expose the prefixed form. Do not hardcode a specific server name. On the first call, use whichever form the available-tool registry advertises — look up the prefix once, then reuse it for the rest of the session. If a short-name call fails with an unknown-tool error, do not guess at the prefix: look it up in the registry and retry with the full name.

• XcodeGlob for file discovery — find is forbidden for files inside the project.
• XcodeGrep for content search — grep/rg is forbidden for files inside the project.
• XcodeRead for file contents — cat/Read is forbidden for files registered in the project.
• XcodeLS for directory listing — ls is forbidden for any path inside the project.
• XcodeUpdate for in-place edits of project-registered text files (xcconfig files, source files) — same filePath / oldString / newString (+ optional replaceAll) signature as the built-in Edit tool, but accepts Xcode workspace-relative paths. Edit is forbidden for files registered in the project. Do not use XcodeUpdate / Edit / plutil to add or update .entitlements keys — use AddEntitlement.
• AddEntitlement for adding or updating a target's entitlements — pass targetName, entitlementKey, entitlementValueType (bool / string / int / stringArray / dictionary), and the value. Always prefer it for entitlement changes; it adds or updates only and cannot remove keys.
• XcodeListTargets for enumerating targets — do not parse project.pbxproj manually. Returns each target's PRODUCT_TYPE_IDENTIFIER and role flags (IS_AGGREGATE, IS_TEST_TARGET, IS_APP_EXTENSION, SUPPORTS_HOSTING_TESTS) directly.

Project root and name are already in the system prompt context. Do NOT run ls to "verify" the project layout before starting. The system prompt already tells you the working directory and the project structure.

Empty XcodeGlob results are not a failure. The .xcodeproj and .xcworkspace are not indexed as files inside the Xcode workspace — XcodeGlob "**/*.xcodeproj" correctly returns 0 matches. Use the project name from system-prompt context instead. Do not fall back to filesystem ls/find.

All Xcode* tools take Xcode workspace-relative paths. XcodeGlob, XcodeGrep, XcodeRead, XcodeLS, XcodeUpdate, XcodeWrite, and XcodeRM interpret their path arguments — and return paths — relative to the Xcode workspace root (what you see at the top of the Project Navigator). Not the git repository root; not the .xcodeproj bundle. Anything the user sees in Xcode (entitlements, xcconfig, plan and decision documents, source files) is reachable via its workspace-relative path; pass that path through these tools as-is, and don't construct absolute filesystem paths for it.

To read or edit a specific file:

• Prefer XcodeRead / XcodeUpdate with the workspace-relative path. XcodeRead reads .entitlements plists too — they're project-registered files, navigable just like any source file — so read them this way. To add or update an entitlement, use AddEntitlement, not XcodeUpdate.

For entitlements files, never derive the path by hand. Each target's authoritative entitlements path is the evaluated value of its CODE_SIGN_ENTITLEMENTS build setting — get it from GetTargetBuildSettings and use it as-is. Do not parse project.pbxproj to reconstruct the path, and do not glob **/*.entitlements: orphaned .entitlements files may exist on disk that aren't referenced by any target. One entitlements file can be referenced by multiple targets.

Fall back to Bash only for operations the Xcode tools cannot do (e.g., git operations).

Bundled Reference Documents

All reference material lives under references/ next to this file.

• references/security-settings-reference.md — the canonical list of security build settings and entitlements this skill tracks, with hardened values, CLI flags, and language scope.
• references/reading-build-settings.md — GetTargetBuildSettings schema, the filter script recipe, the audit-table construction, and the "already hardened" / "deliberately disabled" predicates.
• references/enhanced-security.md — the Enhanced Security capability: build settings, entitlements, supported product types.
• references/pointer-authentication.md — arm64e pointer signing: supported platforms, consumer-side compatibility notes.
• references/universal-binaries-for-libraries.md — universal-binary recipe for library/framework targets (ONLY_ACTIVE_ARCH = NO; pointer authentication adds the arm64e slice automatically), qualifying product types, XCFramework guidance.
• references/security-compiler-warnings.md — the security-focused compiler warnings and settings enabled by Enhanced Security.
• references/cpp-hardening.md — C++ stdlib hardening (CLANG_CXX_STANDARD_LIBRARY_HARDENING) and bounds-safe buffers (ENABLE_CPLUSPLUS_BOUNDS_SAFE_BUFFERS).
• references/typed-allocators.md — type-aware allocator support and the hardened-heap sub-option.
• references/stack-zero-init.md — automatic stack-variable zero-initialization at runtime.
• references/readonly-platform-memory.md — read-only protection of dyld state.
• references/runtime-restrictions.md — dylib and Mach-message platform restrictions.
• references/hardware-memory-tagging.md — MTE entitlements and supported hardware.
• references/additional-settings.md — opt-in diagnostic settings beyond the defaults (may have more false positives).
• references/adoption-strategy.md — recommended ordering for validating Enhanced Security features (lowest-risk to highest-effort).
• references/decision-document.md — how to maintain the persistent xcode-security-settings.md decision document.

The skill ships one helper script:

• scripts/filter_build_settings.py — filters GetTargetBuildSettings JSON to the macros tracked in security-settings-reference.md. See references/reading-build-settings.md for usage.

Common Failure Modes

Symptom	Cause	Correct Response
Tool call fails with "unknown tool" / "tool not found" for XcodeGlob etc.	The harness registers these tools only under their full MCP-prefixed name (mcp__<server>__XcodeGlob) in this environment	Look up the prefix in the available-tool registry, retry once with the full name, then use the full name for the rest of the session.
XcodeGlob "**/*.xcodeproj" returns 0 matches	The .xcodeproj itself isn't a project-indexed file	Use the project name from system context; do not fall back to find or ls
XcodeRead <workspace-relative-path> fails for a file truly inside the .xcodeproj / .xcworkspace bundle (e.g. WorkspaceSettings.xcsettings)	That file isn't a project-navigator member	Translate to filesystem absolute path using the project root from system context, then use Read / Edit. (Does not apply to .entitlements files — those are navigable.)
Read on an entitlements path you derived by hand returns File does not exist	The path was reconstructed from project.pbxproj group nesting or guessed by globbing **/*.entitlements. Xcode's authoritative path for a target's entitlements is the evaluated value of CODE_SIGN_ENTITLEMENTS, not whatever the navigator shows.	Look up CODE_SIGN_ENTITLEMENTS for the target via GetTargetBuildSettings (or read it from the audit table) and use its evaluated value as the path.

Workflow

Phase 1: Briefing

Before doing any work, tell the user — in two or three sentences — what this skill is, what it will do, and roughly how much of their time and attention to expect:

• What it is. An audit of the project's Xcode security build settings and entitlements (compiler warnings, Enhanced Security entitlements, pointer authentication, universal binaries for libraries, etc.).
• What happens. I analyze the project, write an editable plan file at the project root for you to review, and apply only the changes you approve. Nothing is modified until you pick Run.
• Time commitment. A few minutes of my time to analyze (longer on projects with many targets — I'll narrate progress). Then your review time on the plan file, which can be quick or thorough — your call. After Run, applying is fast; two things can pause for your input — the inquiry step (if there are deliberately-disabled settings whose rationale isn't documented), and a final yes/no on whether to keep the plan file in your project as a record. This all usually takes about 15-30 minutes, depending on the number of build targets and how long it takes for you to review and approve the plan.

Keep it tight — the user already invoked the skill knowing they wanted an audit. The briefing exists so they have realistic expectations.

Then check for source control. The project has source control if either:

• The Environment block's Is a git repository field is true, or
• A single filesystem check at the project root finds any of .git, .hg, .svn, .bzr, .fslckout, _FOSSIL_, CVS.

Otherwise the project has no source control. Record this state — Phase 4 Step 3 uses it to decide whether to include the ⚠️ blockquote in the plan file.

After delivering the briefing, pause via AskUserQuestion. If the project has source control:

• Begin audit — proceed to Phase 2.
• Cancel — exit with "Cancelled — no changes applied."

If the project has no source control, tell the user first: "It is strongly recommend setting up source control before continuing. This skill modifies build settings and entitlements; without something like Git, rollback requires manual undo and you won't have a clean way to review the differences. Xcode has built-in support for Source control management" Then ask:

• Set up source control first (Recommended) — exit with "Set up source control and re-run the skill."
• Proceed without source control — proceed to Phase 2; Phase 4 Step 3 will surface the no-source-control reminder again in the plan file.
• Cancel — exit with "Cancelled — no changes applied."

The pause exists so the briefing stays on screen long enough to read; Discovery and Analysis output would otherwise scroll it away. Failing early when there's no source control avoids spending minutes on discovery and analysis only for the user to bail at plan-approval time.

Phase 2: Discovery

Read the Environment block in the system prompt. Relevant fields:

• Primary working directory — the project root (the project name is the basename).
• Is a git repository — whether the project is git-tracked (used by the source-control check in Phase 1).

Track Progress

Every per-target / per-setting action that needs to happen must have its own task for transparency.

• Phase 1 (Briefing) is one task that completes when the user picks Begin audit / Cancel.
• Phase 3 creates one task per target (Audit <target>); the task closes once Phase 3 has produced both the per-target audit-table rows and (for supported product types) the Enhanced-Security category for that target. Phase 3 stores all per-target state in the task's description field (see Phase 3 Step 4 for the format) so later phases can read it back via TaskGet. Phases 4–7 read these task descriptions.
• Phase 4 (Plan & Approve) is one task that completes when the user picks Run/Cancel.
• On Run, Phase 4 step 5 parses the plan and creates fine-grained tasks. For each apply task it embeds that target's delta (extracted from the corresponding Audit <target> task's description) into the apply task's own description so Phase 5 doesn't have to look it up again.
  • For each Enhanced Security sub-item that's checked:
    • Enable Enhanced Security: Enable Enhanced Security at project level (one task). On pbxproj-only projects, this task encapsulates the guide-and-verify flow described in Phase 5 Step 1a.
    • Update entitlements: one Apply Enhanced Security entitlements to <target> per target needing changes.
    • Hardware memory tagging: Apply Hardware Memory Tagging (one task; walks supported targets internally).
  • Apply Basic Clang Safety Warnings if checked.
  • Apply Additional Diagnostic Settings if checked.
  • Emit Bounds Safety Adoption guidance if checked.
  • One Inquire about <MACRO> on <target> per Phase-6 candidate (only if "Inquire about disabled settings" is checked).
  • Report and update decision document.
  • Prompt to remove plan file — always last; also fires on error paths.

When entering each phase or sub-step:

• Print one line naming the phase or sub-step in plain English — never the phase number. Use the phase's name (e.g., "▶ Briefing", "▶ Analyzing project", "▶ Plan & Approve", "▶ Applying settings"); for sub-steps, name what's being done (e.g., "▶ Detecting languages", "▶ Building the audit table").
• Update the task to in_progress.

When finishing each phase or sub-step:

• Print one line: "✓ " with a brief outcome if applicable (e.g., "✓ Detecting languages: C and Swift found.").
• Update the task to completed.

Phase 3: Analyze Project and Settings

No user interaction. Gather facts in the background.

Step 1: Locate the existing decision document

XcodeGlob '**/xcode-security-settings.md'. If found, XcodeRead it and extract languages + prior setting decisions with their statuses and rationale. This informs subsequent phases.

Step 2: Detect languages

One XcodeGlob per language. Empty result is not a failure — record the language as absent.

• **/*.c → C
• **/*.cpp, **/*.cxx, **/*.cc → C++
• **/*.m → Objective-C
• **/*.mm → Objective-C++
• **/*.swift → Swift

Objective-C++ implies C++ is present. .mm files contain C++ source, so any audit gated on "C++ present" (C++ stdlib hardening, bounds-safe-buffers guidance, CLANG_ANALYZER_OSOBJECT_C_STYLE_CAST, etc.) must fire when Objective-C++ is detected, even when no .cpp/.cxx/.cc files exist.

Filename extension is not authoritative. An Xcode project can override a file's compiled language via explicitFileType / lastKnownFileType in project.pbxproj — most commonly a .m file marked sourcecode.cpp.objcpp (compiled as Objective-C++), or a .h marked sourcecode.c.h / sourcecode.cpp.h. To catch these overrides, grep -E 'sourcecode\.cpp\.[a-zA-Z0-9]+' <project-root>/<ProjectName>.xcodeproj/project.pbxproj via Bash. project.pbxproj is Xcode's project description file inside the .xcodeproj bundle; read it directly. Treat any sourcecode.cpp.objcpp match as both Objective-C++ and C++; treat any other sourcecode.cpp.* match as C++.

Step 3: Build the audit table

See references/reading-build-settings.md for column definitions, the construction recipe, and the canonical predicates ("already hardened", "at default OFF", "deliberately disabled"). At a glance:

1. Call XcodeListTargets to enumerate targets. Skip entries with IS_AGGREGATE = true (they have no product type). Record TARGET_NAME, CONTAINING_PROJECT, and PRODUCT_TYPE_IDENTIFIER for each remaining target — Step 4 categorizes targets by PRODUCT_TYPE_IDENTIFIER directly (no inference).
2. For each target: TaskCreate "Audit <target>", set in_progress. Call GetTargetBuildSettings, run scripts/filter_build_settings.py over the resulting JSON, and record evaluatedValue and setAtTargetLevel (yes if targetValue is present in the JSON) per tracked macro. Hold these rows ready to write into the task's description in Step 4 (along with the category). Leave the task in_progress — Step 4 closes it.
3. Scan for explicit settings in two passes with the filter regex: XcodeGrep over *.xcconfig, and grep -nE '<filter regex>' <project-root>/<ProjectName>.xcodeproj/project.pbxproj via Bash. project.pbxproj is Xcode's project description file inside the .xcodeproj bundle; read it directly. Record per-macro numMatchesInXCConfigs, numMatchesInPbxproj, and the file:line citations.
4. The audit table is the joined view: one row per (target, tracked macro). Phases 4, 5, and 6 all consume this table; nothing else is re-fetched.

This step scales with target count: each GetTargetBuildSettings call takes several seconds, and there is one per target. On projects with roughly ten or more targets it can take a few minutes.

Step 4: Per-target Enhanced-Security state

Route each target into one of three categories by the PRODUCT_TYPE_IDENTIFIER recorded in Step 3:

• Entitlements-supported — product type is in the "Supported Product Types" list of references/enhanced-security.md (applications, XPC services, system extensions, driver extensions [build settings only], tools). Read the entitlements plist at the path stored in this target's CODE_SIGN_ENTITLEMENTS build setting and classify the target as Up-to-date, Partial, Off, or No-entitlements-file. Multiple targets can share the same CODE_SIGN_ENTITLEMENTS path; classify each target independently.
• Library/framework — product type is in the qualifying set listed in references/universal-binaries-for-libraries.md (frameworks, static frameworks, static libraries, dynamic libraries). No entitlements read. Phase 5 will configure the universal-binary recipe (ONLY_ACTIVE_ARCH = NO) for these.
• Skipped — anything else (test bundles, app extensions, etc.).

Now write everything Phase 3 has learned about this target into the Audit <target> task's description via TaskUpdate, then set it completed. The description holds the entire per-target state Phases 4–6 need to consult later. Format:

Category: <category> [/ <sub-state>]      # e.g. "Entitlements-supported / Partial", "Library/framework", "Skipped"
Entitlements path: <evaluated CODE_SIGN_ENTITLEMENTS>     # omit for Library/framework and Skipped
SDKROOT: <value>
SUPPORTED_PLATFORMS: <value>
Missing entitlements: <comma-separated short names>      # Entitlements-supported only; omit if empty
Deliberately-disabled: <MACRO>=<value> (<source>[+<source>...]), ...   # one per disabled row; sources ⊆ {target-level, xcconfig, pbxproj} joined with '+' when more than one applies; omit the line entirely if none

Audit table:
  <MACRO>=<value> setAtTargetLevel=<yes|no> numMatchesInXCConfigs=<n> numMatchesInPbxproj=<n> matchLocations=<citations>
  ...

The Category line is first so any client that surfaces a snippet shows something meaningful. The Audit-table block is the per-(target, tracked macro) rows from Step 3 in key=value form — one line per tracked macro, using the canonical column names defined in references/reading-build-settings.md. matchLocations carries the file:line citations in the same <source>:<file>:<line>[,<line>...] format used throughout. Library/framework and Skipped targets get this Category line, the platform fields, and the Audit-table block, then complete immediately (no entitlements read).

On large projects this iterates over many .entitlements plists — if Step 3 took noticeable time, this one will too.

Phase 4: Plan & Approve

This phase produces a tailored, editable plan file that the user reviews before any changes happen. Once approved, Phases 5–7 run end-to-end with no further prompts.

Step 1: Source-control state

Source control was checked in Phase 1, and the user already accepted any no-source-control state at that point. Phase 4 Step 3 uses the recorded state to decide whether to include the ⚠️ blockquote in the plan file.

Step 2: Skip if everything is already configured

TaskList the Audit <target> tasks and TaskGet each. Early-exit if all default-checked plan items are already at their target state:

• Every Enhanced-Security category (from each task's Category: line) is Up-to-date or Skipped.
• Every relevant Basic-Clang-safety setting is already hardened on every applicable target (per each task's Audit-table block).
• No task's Deliberately-disabled: line yields a row (after the Phase-6 exclusions below).

Optional follow-ups (Additional diagnostic settings, Bounds safety adoption) do not block early-exit. Report "Everything in scope is already configured" and exit; do not write a plan file.

Step 3: Write the plan file

Create xcode-security-audit-plan.md at the root of the Xcode workspace via XcodeWrite (path: xcode-security-audit-plan.md, no parent group). XcodeWrite both writes the file to disk under <project-root>/ and registers it in the project so the user can open it directly from Xcode's Project Navigator.

Include only items that apply to the project (see omission rules below). Use this template — substitute the placeholders in <…>:

# Xcode Security Audit — Plan
**Project:** <name> · <N> targets · languages: <list>
**Generated:** <YYYY-MM-DD>
> ⚠️ **No source control detected.** This skill modifies build settings and entitlements.
> Without source control (e.g., Git), rollback requires manual undo. Consider [setting up source control](doc://com.apple.documentation/documentation/xcode/configuring-your-xcode-project-to-use-source-control) before picking **Run**.
Edit the items below — set what steps to perform now, or leave them unchecked to defer them.
## Phases
- [x] **[Enhanced Security](doc://com.apple.documentation/documentation/Xcode/enabling-enhanced-security-for-your-app)** — the project's runtime-protection bundle. Apply to: <target list>.
  - [x] **Enable Enhanced Security** — sets `ENABLE_ENHANCED_SECURITY=YES` at the project level. (Your project doesn't use a project-level xcconfig — I'll walk you through enabling it in Xcode's Build Settings UI yourself, then verify by reading project file.)
  - [x] **[Update entitlements](doc://com.apple.documentation/documentation/BundleResources/Entitlements/com.apple.security.hardened-process)** — adds the hardened-process entitlement family per target (Memory Safety, Runtime Protections).
  - [x] **[Hardware memory tagging](doc://com.apple.documentation/documentation/BundleResources/Entitlements/com.apple.security.hardened-process.checked-allocations)** — adds the soft-mode MTE entitlement on supported platforms (<target list filtered to MTE-supported platforms>).
- [x] **Basic Clang safety warnings** — <N> settings, applied to all C/C++/ObjC targets.
- [x] **Inquire about disabled settings** — <M> found (e.g., `<setting>=NO` on `<target>`). May trigger follow-up questions if no rationale is documented.
- [ ] **Additional diagnostic settings** — extra warnings/checkers. Produces more findings to review. See `references/additional-settings.md`.
- [ ] **Bounds safety adoption** — pointer to a separate skill. No changes applied here.
## Decision document
The skill creates or updates `xcode-security-settings.md` to record every setting decision (kept, deferred, disabled, with rationale). Edit the path to relocate.
- Path: `xcode-security-settings.md`

Include the ⚠️ blockquote only when the project has no source control; omit it otherwise.

Include the trailing parenthetical on the Enable Enhanced Security sub-item only when the project is pbxproj-only (no *.xcconfig files surfaced by Phase 3's project-wide scan); omit it otherwise.

The decision document should live in the same directory as the rest of the documentation, or at the project level.

Item omission rules

A plan item is omitted entirely when it doesn't apply:

• Enhanced Security — omit (along with all three sub-items) if every supported-product-type category from Phase 3 step 4 is Up-to-date or Skipped.
• Enable Enhanced Security (sub-item) — never omitted when Enhanced Security is shown; the trailing pbxproj-only parenthetical is the only conditional part.
• Update entitlements (sub-item) — never omitted when Enhanced Security is shown.
• Hardware memory tagging (sub-item) — omit if no target's SUPPORTED_PLATFORMS / SDKROOT matches macosx, iphoneos, iphonesimulator, xros, or xrsimulator.
• Basic Clang safety warnings — omit if pure-Swift, or if every relevant setting is already hardened on every applicable target.
• Inquire about disabled settings — omit if the deliberately disabled predicate yields no rows (after excluding any ENABLE_POINTER_AUTHENTICATION[sdk=*simulator*] = NO row — a simulator-only opt-out is expected and harmless, since the simulator has no arm64e).
• Additional diagnostic settings — never omitted; always offered.
• Bounds safety adoption — omit if Phase 3 step 2 detected no C, C++, or Objective-C++ (counting sourcecode.cpp.* overrides as C++).

Default check state

Items under Phases are default-checked ([x]); items ([ ]) are default-unchecked. The user can flip either by editing the plan file before picking Run.

Step 4: Ask for approval

Tell the user:

"Plan written to xcode-security-audit-plan.md and added to the Xcode project — open it to review. Edit it as needed — uncheck or delete items to skip them; edit the decision document path to relocate. When ready, pick Run. Pick Cancel to abort without changes. Nothing is modified until you pick Run."

Then ask via AskUserQuestion with single-select options:

• Run — proceed to "Phase 5"
• Cancel — abort

Step 5: Handle the response

If Cancel: run the final cleanup task (Prompt to remove plan file, see "Phase 7: Report and Decision Document" below). The keep-or-remove prompt is offered on Cancel too, so the user's choice to abandon the audit doesn't silently differ from a normal completion. Report "Cancelled — no changes applied," and exit the skill.

If the plan file is missing at re-read time (the user deleted it from disk before responding), treat it as a Cancel — and skip the Prompt to remove plan file task (there's nothing to remove).

If Run: XcodeRead xcode-security-audit-plan.md. Parse:

• Each - [x] or - [X] bullet is a checked item; the item name is the bold portion (between **…**).
• Items written as - [ ] and items deleted from the file are skipped — both produce identical skip behavior.
• Under the "Decision document" heading, the value after Path: is the decision document location.

Create the fine-grained tasks listed in Track Progress:

• For each Apply Enhanced Security entitlements to <target> task, copy the per-target delta from the corresponding Audit <target> task's description (Category:, Entitlements path:, Missing entitlements:) into the apply task's own description so Phase 5 reads from one place.
• To create the Inquire about <MACRO> on <target> tasks (only when Inquire about disabled settings is checked), TaskList the Audit <target> tasks and TaskGet each; the Deliberately-disabled: line of each description lists that target's candidate rows. Apply the Phase-6 exclusions documented below when filtering.
• When creating the Report and update decision document task, put the parsed decision-document path in its description so Phase 7 reads it from there.

If the parsed plan has zero checked items, run the final cleanup task immediately and report "Plan was empty — nothing to do."

Phase 5: Apply Settings

Read build-setting state from each Audit <target> task's description (the Audit-table block) when needed; per-target apply state comes from each apply task's own description.

How to apply build settings:

• Project uses .xcconfig files — edit the xcconfig directly. Supports both project-level and target-level settings.
• Project uses .pbxproj only — use UpdateTargetBuildSetting for target-level settings. Ask the user to enable project-level settings. Once the user responds that it was set, verify that it was set correctly using grep on the project file.
• Mixed — if a target has an .xcconfig file, edit the xcconfig. Otherwise, use the Xcode build setting tools. Never introduce a new configuration method.

ENABLE_ENHANCED_SECURITY must be set at project level such that any existing and future build targets inherit this setting. This setting should be disabled only after serious consideration and with strong justification.

Step 1: Enhanced Security

1a. Enable Enhanced Security at the project level. Walk the Enable Enhanced Security at project level task. Two paths inside it:

• Project uses a project-level xcconfig — write ENABLE_ENHANCED_SECURITY = YES to the xcconfig via XcodeUpdate. Mark the task completed.
• Project is pbxproj-only — no MCP tool can write a project-level pbxproj setting directly, so the user has to set it in Xcode. Give these exact steps (repeat them verbatim whenever you re-show them): "Open the project in Xcode. Select the project in the Project Navigator (the top entry, not a target). Go to Build Settings, switch the scope to All / Combined, search for ENABLE_ENHANCED_SECURITY, and set the project-level column (left of the target columns) to YES. Save." Then AskUserQuestion with two options: I've enabled it and Show me the steps again. On I've enabled it, verify with Bash: grep -E 'ENABLE_ENHANCED_SECURITY *= *YES' <project-root>/<ProjectName>.xcodeproj/project.pbxproj. If a match is found, mark the task completed. If not, do not move on: the confirmation was most likely accepted without the change actually being made — an accidental Enter, or Save was missed. Say that plainly, re-show the steps verbatim, and ask again. Loop — re-run the grep after each confirmation and re-show the steps every time it still isn't found — until the grep finds ENABLE_ENHANCED_SECURITY = YES.

1b. Update Enhanced Security entitlements. The fine-grained Apply Enhanced Security entitlements to <target> tasks created in Phase 4 step 5 already enumerate the targets needing changes (the Partial, Off, and No-entitlements-file categories — Up-to-date and Skipped are excluded). Walk those tasks.

Read references/enhanced-security.md for the full key list, defaults, and the supported product-type list. For details on individual sub-options, see:

• references/pointer-authentication.md — arm64e pointer signing
• references/typed-allocators.md — type-aware memory allocation
• references/stack-zero-init.md — automatic stack variable zeroing
• references/readonly-platform-memory.md — dyld state protection
• references/runtime-restrictions.md — dylib and Mach message restrictions
• references/security-compiler-warnings.md — security-focused compiler warnings
• references/cpp-hardening.md — C++ stdlib hardening and bounds checking
• references/hardware-memory-tagging.md — ARM MTE

Pointer authentication and binary dependencies. Enhanced Security is a bundle of independent protections; only pointer authentication cascades to arm64e. Always recommend ENABLE_ENHANCED_SECURITY = YES at the project level. If the project has a binary Swift Package, xcframework, or prebuilt framework that does not ship arm64e, the right mitigation is to override ENABLE_POINTER_AUTHENTICATION = NO at the target level on every target that links the dependency — not to skip Enhanced Security. List the offending dependencies in the report so the user can ask the vendor for arm64e support and lift the override later.

Producer side — universal binary on library/framework targets. Pointer authentication is highly recommended on library and framework targets too — do not skip it on the grounds that the universal recipe produces a larger on-disk artifact (RAM footprint and execution cost are unchanged; dyld loads only one slice). Enabling pointer authentication already builds both the arm64 and arm64e slices automatically, so no explicit ARCHS is needed. For each target in the Library/framework category from Phase 3 step 4, Phase 5 below applies a target-level ONLY_ACTIVE_ARCH = NO (Release) so the distributed build emits both slices and consumers can pick either. See references/universal-binaries-for-libraries.md.

For each task:

1. Compose the change set from this apply task's description (the Category: / Missing entitlements: lines copied in from the audit task).

   • Entitlements-supported categories (Partial / Off / No-entitlements-file): add/update entitlements via AddEntitlement; create .entitlements if missing and wire CODE_SIGN_ENTITLEMENTS. DriverKit targets are supported for build settings only — skip entitlement changes for them.
   • Library/framework category: no entitlements work. The change set is the universal-binary recipe — see item 2 below.

2. Per-target build settings. ENABLE_ENHANCED_SECURITY = YES is already set at the project level (Step 1a above), so it cascades ENABLE_POINTER_AUTHENTICATION = YES to every target. Simulator builds need no override — the build system drops arm64e for simulator SDKs automatically. The only per-target override: for each target that links a binary dependency that doesn't ship arm64e, set an unconditional target-level ENABLE_POINTER_AUTHENTICATION = NO (that dependency can't be linked as arm64e on any platform). Skip targets that already have an explicit target-level value (per the Audit-table block in their Audit <target> task).

   For each Library/framework-category target where pointer authentication will end up enabled (the target's platform supports arm64e and there is no existing target-level ENABLE_POINTER_AUTHENTICATION = NO), also pre-write a target-level ONLY_ACTIVE_ARCH = NO (Release configuration) so the distributed build emits both the arm64 and arm64e slices. Use the target's xcconfig if it has one, otherwise UpdateTargetBuildSetting. Do not write an explicit ARCHS — pointer authentication appends the arm64e slice automatically, so a hard-coded ARCHS is redundant. Skip targets that already have an explicit ONLY_ACTIVE_ARCH value (per the Audit-table block in that target's Audit <target> task).

   Do not auto-enable default-OFF sub-options (MTE family); those are handled by Step 3 below if checked.

3. Apply the change set per target: add or update entitlements with AddEntitlement (creating the .entitlements file and wiring CODE_SIGN_ENTITLEMENTS when the target has none); and apply build-setting changes.

After all targets are processed, report: "Enabled Enhanced Security on N target(s). Added a target-level ENABLE_POINTER_AUTHENTICATION = NO on T target(s) that link arm64e-less binary dependencies. Configured universal binary on U library/framework target(s)." If the project is pbxproj-only and Verify Enhanced Security at project level succeeded, append: "Enhanced Security is enabled at the project level (you set it in Xcode)." If the user skipped the guide step, append: "Project-level ENABLE_ENHANCED_SECURITY was not enabled this run — re-run the skill after enabling it in Xcode."

The user already approved this in "Phase 4" — no further prompt is needed.

The per-target Apply Enhanced Security entitlements tasks dominate Phase-5 wall time on multi-target projects. Each one edits the target's .entitlements plist.

Step 2: Basic Clang Safety Warnings

If pure Swift, skip. For each setting, consult that target's Audit <target> task description (the Audit-table block) and skip individual settings whose row is already hardened. Otherwise apply target-level (see "How to apply build settings"):

• GCC_WARN_ABOUT_RETURN_TYPE = YES_ERROR — non-void function returning without a value is undefined behavior; callers read whatever happened to be in the return register. Promoting to error catches this at compile time. YES_ERROR is the documented Xcode value for "treat this specific warning as an error" — it does not flip every warning into an error.
• GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE — reading uninitialized stack values leaks prior frame contents and lets attackers control flow with stale data. Aggressive mode warns on more cases (e.g., conditional initialization paths).
• CLANG_WARN_IMPLICIT_FALLTHROUGH = YES — implicit switch fallthrough is one of the most common sources of branching bugs; the warning forces an explicit [[fallthrough]] / __attribute__((fallthrough)) whenever intentional.
• GCC_WARN_64_TO_32_BIT_CONVERSION = YES — silent narrowing of size_t/pointers to int is a classic source of integer-truncation vulnerabilities (length checks pass on the wide value, then fail open on the narrow one).
• GCC_TREAT_IMPLICIT_FUNCTION_DECLARATIONS_AS_ERRORS = YES (C/ObjC only) — implicit declarations were removed in C99 and produce wrong calling conventions and wrong return-type assumptions in modern C. Always an error.
• CLANG_ANALYZER_SECURITY_FLOATLOOPCOUNTER = YES — floating-point loop counters can stall or overshoot due to rounding; the analyzer flags loops where this can become a security-relevant bug.
• CLANG_ANALYZER_SECURITY_INSECUREAPI_RAND = YES — rand() / random() are predictable PRNGs unsuitable for any security purpose; analyzer flags their use so callers switch to arc4random_uniform or SecRandomCopyBytes.
• CLANG_ANALYZER_SECURITY_INSECUREAPI_STRCPY = YES — flags strcpy, strcat, and friends that are inherently unsafe; callers should switch to size-bounded variants (strlcpy, strlcat, snprintf).

The two YES_ERROR / … ERRORS = YES settings are scoped: they only promote their own specific warning to an error, not all warnings in the project.

Report briefly: "Enabled additional compiler warnings."

Step 3: Hardware Memory Tagging

If the Hardware memory tagging sub-item (under Enhanced Security) was unchecked or deleted, skip this step.

Hardware memory tagging is supported only for targets whose SUPPORTED_PLATFORMS (or SDKROOT) is macosx, iphoneos / iphonesimulator, or xros / xrsimulator. Hardware backing requires an iPhone or iPad with an A19 chip or later, or a Mac or Apple Vision Pro with an M5 chip or later.

Read references/hardware-memory-tagging.md and apply the soft-mode MTE entitlement to every supported target. The user already approved this in "Phase 4" — no further prompt is needed.

Step 4: Additional Diagnostic Settings

If the Additional diagnostic settings plan item was unchecked or deleted, skip this step.

Read references/additional-settings.md and follow it. The user already approved this in "Phase 4" — no further prompt is needed.

Step 5: Bounds Safety Adoption

If the Bounds safety adoption plan item was unchecked or deleted, skip this step.

This step does not apply changes — it emits guidance only.

For C projects (C present per Phase 3 step 2), print:

"To adopt ENABLE_C_BOUNDS_SAFETY (annotation-based bounds safety for C), invoke the adopt-c-bounds-safety skill."

For C++ projects (C++ or Objective-C++ present per Phase 3 step 2 — including any sourcecode.cpp.* override on files with other extensions), print:

"To adopt ENABLE_CPLUSPLUS_BOUNDS_SAFE_BUFFERS (C++ bounds-safe buffer patterns), read the documentation at https://clang.llvm.org/docs/SafeBuffers.html"

Phase 6: Inquire about Disabled Settings

If the Inquire about disabled settings plan item was unchecked or deleted, skip this phase.

This phase pauses for one user response per deliberately-disabled setting that lacks a documented rationale. If the candidate list is long, surface the count up front so the user knows what to expect ("I found 7 deliberately-disabled settings; let me ask about each").

A row is a candidate when the deliberately disabled predicate (defined in references/reading-build-settings.md) holds. TaskList the Audit <target> tasks and TaskGet each; the Deliberately-disabled: line of each description lists that target's candidate rows. Exclude any simulator-scoped ENABLE_POINTER_AUTHENTICATION[sdk=*simulator*] = NO row (expected and harmless — the simulator has no arm64e); flag an unconditional ENABLE_POINTER_AUTHENTICATION = NO, since that disables pointer authentication on device builds. Restrict to settings whose Scope (in references/security-settings-reference.md) covers a language detected in Phase 3 step 2.

For each candidate, walk the corresponding Inquire about <MACRO> on <target> task created in Phase 4 step 5:

• If the decision document has an entry with status Disabled and a rationale → note it in the report and move on.
• Otherwise → AskUserQuestion: "I found <MACRO> explicitly set to NO with no explanation. Is there a reason for this?" Double-check that the macro is deliberately disabled and not merely at Xcode's default OFF — only call out explicit overrides. Record the rationale (or recommend re-enabling if none).

Same flow applies to ENABLE_ENHANCED_SECURITY = NO if it appears on any task's Deliberately-disabled: line.

Phase 7: Report and Decision Document

Produce a lean summary:

1. Enabled — project-wide settings that were enabled.
2. Enhanced Security per target — one line per target: name, final status (up-to-date / applied / skipped-by-user), terse delta (entitlements added, whether an entitlements file was created). Roll up Skipped targets into one line.
3. Already active — settings already configured correctly.
4. Inquired — settings found disabled and the outcome of the inquiry.

Decision document. TaskGet the Report and update decision document task to read the decision-document path. Then read references/decision-document.md and follow it to create or update the document at that path.

After Phase 7 — and on any error path during Phases 5–7 — this final task runs:

1. Prompt to remove plan file — ask the user via AskUserQuestion: "The audit is complete. Remove the plan file xcode-security-audit-plan.md from your project?"
   • Yes, remove it (Recommended) → XcodeRM xcode-security-audit-plan.md deleteFiles:true
   • No, keep it → leave it in place; it stays in the Project Navigator as a record of what was approved. The user can delete it later from Xcode or Finder.

If removal fails, warn the user but do not block exit.

User-Facing Interaction Guidelines

• Keep replies lean. Short sentences.
• Speak in complete sentences. No fragments. Don't emit telegraphic noun phrases like "No existing decision document." — write a full sentence ("I didn't find an existing decision document — I'll create one at the end.").
• Phases are internal. Never reference phase numbers or step numbers in user-facing prose. Describe outcomes plainly: say "I won't need to ask you about disabled settings" instead of "there will be no Phase 6 inquiry questions". This applies to narration, status lines, and any AskUserQuestion text.
• No skill-internal jargon. Don't use words like "catalog", "audit table" in user-facing prose — those are internal to the skill. Describe what's happening in everyday Xcode terms: "checking known security build settings", "the list of targets", "the analysis I just ran".
• Keep user questions minimal. Three scheduled questions: the briefing-acknowledgment prompt (Begin audit / Cancel) at the end of "Phase 1", the plan approval prompt (Run / Cancel) at the end of "Phase 4", and the keep-or-remove-plan-file prompt at the end of "Phase 7". Other questions are situational: inquiries about deliberately-disabled settings during "Phase 6" (only when an explicit = NO lacks a documented rationale), and the Enable Enhanced Security at project level confirmation prompt (only for pbxproj-only projects when that sub-item is checked).
• Report progress so the user can track: "Enabling...", "Evaluating...", "Keeping/Reverting..."
• Use AskUserQuestion for the briefing acknowledgment (Begin audit / Cancel), for the plan approval (Run / Cancel), for inquiring about disabled settings during "Phase 6", for the Enable Enhanced Security at project level confirmation in Phase 5 Step 1a (pbxproj-only), and for the keep-or-remove-plan-file prompt at the end of "Phase 7".
• When asking a question provide context the user needs to answer the question. For example, describe the benefit of the security protection before asking whether to enable it. Describe it in terms of the protection it provides, not how it is enabled.
• When emitting lists of Xcode build settings, use bullet lists Don't use comma-separated lists.