SAP Clean Core ATC Classification

Inventory a package of custom code and bucket every Z/Y object into Clean Core Levels A–D based on the SAP APIs it uses — the "is this cloud-ready?" audit.

This is different from migrate-custom-code: that skill fixes one object's ATC findings; this one produces a package-wide classification report with per-object levels, used to plan a clean-core / BTP migration. It combines ARC-1 (ATC + source access) with mcp-sap-docs (released-API classification data from SAP/abap-atc-cr-cv-s4hc).

Clean Core Levels (what they mean)

Source: SAP/abap-atc-cr-cv-s4hc — SAP's official machine-readable release state list.

Smart Defaults (apply silently, do NOT ask)

Input

The user provides a package (preferred) or a comma-separated object list, plus optional target system type.

• Package (e.g., Z_FI_CUSTOM): audit every custom object in it
• Object list (e.g., ZCL_POSTING, ZR_SALES_REPORT): audit only the named ones
• Target system type: public_cloud (default) | btp | private_cloud | on_premise

If neither package nor object list is given, ask which to use. Do NOT audit "everything" — that's never what the user wants.

Step 1: Enumerate Custom Objects

1a. Package path

SAPRead(type="DEVC", name="<package>")

Filter results to keep only PROG | CLAS | INTF | FUGR | FUNC | DDLS | BDEF | SRVD | TABL with names starting Z, Y, or a customer namespace. Skip subpackages (audit them separately) unless the user says "recursive".

1b. Object-list path

For each name, resolve the type:

SAPSearch(query="<name>")

Use the first exact match.

Step 2: Extract SAP API References per Object

For each custom object, collect the list of SAP-shipped objects it references.

2a. Use SAPContext for dependency extraction

SAPContext(type="<type>", name="<object_name>", depth=1)

SAPContext returns a dependency list. Keep only dependencies whose names do NOT start with Z/Y/customer-namespace — those are SAP references. Record each as (objectType, objectName).

SAPContext supports CLAS, INTF, PROG, FUNC, DDLS (on-prem) and CLAS, INTF, DDLS (BTP). For other types (FUGR, BDEF, SRVD, TABL), fall back to reading the source with SAPRead and extracting SAP class / interface / function references with a regex scan over lines (e.g., CL_*, IF_*, SAP*, CALL FUNCTION '...'). Mark these references as "static-scan" in the report so the user knows confidence is lower than AST-derived deps.

2b. Also run ATC for cloud readiness

SAPDiagnose(action="atc", type="<type>", name="<object_name>", variant="ABAP_CLOUD_READINESS")

If ABAP_CLOUD_READINESS doesn't exist on the system, use the system default (omit variant — that runs the system's configured default check variant) and note this in the report. On-premise systems often ship S4HANA_READINESS_<release> (e.g. S4HANA_READINESS_2023) or SAP_CLOUD_PLATFORM_DEFAULT instead of ABAP_CLOUD_READINESS. ATC findings complement the API classification — a released API can still be used incorrectly.

ATC skips `$TMP` / local objects (verified live on S/4HANA 2023). A check run against a $TMP object resolves to an empty object set and returns zero findings — that's "not checked", not "clean". Package-wide classification only works on transportable packages. If a package is local/$TMP, note in the report that ATC results are unavailable and fall back to the mcp-sap-docs API classification alone. A finding count of 0 on code you expect to be flagged is almost always the $TMP trap, not clean code.

Step 3: Classify Each SAP Reference via mcp-sap-docs

For each unique SAP object the custom code references:

sap_get_object_details(object_type="<type>", object_name="<name>", system_type="<target>", target_clean_core_level="A")

This returns:

• cleanCoreLevel — A, B, C, or D
• state — released | deprecated | classicAPI | stable | notToBeReleased | noAPI
• complianceStatus — compliant | non_compliant vs. the target level
• successorObjects — replacement recommendations if deprecated

Cache results by (object_type, object_name) — the same SAP class is often referenced from many Z-objects.

If an object isn't found in the dataset (found: false), classify as D (unknown / no API) and flag it as requiring manual review.

Step 4: Roll Up to Per-Object Level

Each custom object's level is the highest (worst) level among its SAP references:

Record per object:

• Object level (A/B/C/D)
• Reference breakdown (counts per level)
• Top 3 worst references with their successors (if any)
• ATC cloud-readiness findings count (Priority 1/2/3)

Step 5: Emit the Report

5a. Headline summary

Clean Core Audit — <package_or_list>
Target system: <target>   ATC variant: <variant>

Objects audited:  42
  Level A:  12  (29%)  — ready for ABAP Cloud as-is
  Level B:  18  (43%)  — on-prem only; rewrite for cloud
  Level C:   8  (19%)  — uses internal APIs; plan replacement
  Level D:   4   (9%)  — high risk; manual review required

5b. Per-level tables

For each level (start with D, work down — worst first):

Level D — High Risk (4 objects)

Object                    Non-compliant refs  Top violation           ATC P1
ZCL_MIGRATION_HELPER      8                   CL_SALV_TREE_WRAPPER    3
ZR_OLD_POSTING           12                   SAPLSMTR_NAVIGATION     5
...

5c. Replacement suggestions (Level B/C/D only)

For the top 10 most-referenced deprecated APIs, show {deprecated → successor} pairs with counts:

CL_GUI_ALV_GRID  (used in 18 Z-objects)  →  CL_SALV_TABLE  (A)
CL_IXML          (used in 12 Z-objects)  →  XML transformations (A)
...

5d. Follow-up Options

Offer next steps:

• "Want per-object detail for Level D objects?" (drill into the 4 riskiest)
• "Want to migrate one of these objects now?" (→ migrate-custom-code)
• "Want to see which Z-objects are even USED?" (→ sap-unused-code — no point migrating dead code)
• "Want to document the Level A objects as reference examples?" (→ sap-object-documenter)
• "Want a reviewed dossier with saved evidence, customer questions, and visualizations?" (→ sap-migration-dossier)

Error Handling

Caveats

What this skill is NOT

• Not a migration tool — it classifies risk; use migrate-custom-code to actually fix.
• Not a replacement for SAP's Custom Code Migration app — that tool has more depth (runtime usage analysis, simplification DB, transport impact). This skill is a fast, LLM-friendly approximation.
• Accuracy depends on mcp-sap-docs dataset freshness — the SAP/abap-atc-cr-cv-s4hc repo is updated per S/4HANA release.

BTP vs On-Premise

• BTP audit (`system_type=btp`): Level B becomes non-compliant — BTP only accepts Level A. Stricter than public_cloud.
• On-premise audit (`system_type=on_premise`): Level A+B are both compliant. Use this when the goal is "does my custom code survive the next S/4HANA upgrade?" rather than "can I run this in the cloud?".

When to Use This Skill

• Planning a move from ECC → S/4HANA Cloud
• Planning a move from ECC → ABAP Cloud on BTP
• Quarterly custom-code health check
• Before a major release upgrade (to flag high-risk objects early)
• Scoping a custom-code retirement project (combine with sap-unused-code)