legacy-code-doc

# Legacy Code Documentation Produce documentation for ABAP objects that have none. The output is for two audiences at once: a developer who must change the code next month, and a manager deciding whether it survives the next migration. ## Prerequisites - **sap-adt-mcp ≥ 0.8.1** connected to the target system (`adt_ping` to verify). - **NetWeaver 7.4x+** — only core ADT read endpoints are needed (source read, search, where-used). `adt_read_table` examples additionally need **NW 7.55+**; skip data sampling on older systems. - **SAP user authorizations:** repository display only (S_DEVELOP display). - **Read-only mode: fully supported** — this skill never writes to SAP. (It may write the documentation to a local file if the user asks.) - **Large sources:** `adt_get_source` output is capped per call (~64 KB). For big programs paginate with `firstLine`/`lastLine`, or slice with `onlyMethod`. Never assume one call returned the whole object — check `truncated`/`totalLines`. ## Workflow ### 1. Scope the object `adt_search_objects` if only a fuzzy name is known. Identify the object type — the strategy differs: - **Program (PROG):** fetch the main source, then list its includes (`adt_browse_package` on its package, or INCLUDE statements from source) and fetch each include that carries logic. - **Class (CLAS):** fetch `definitions` first (the public contract), then `implementations` method by method (`onlyMethod`) for the ones that matter. - **Function group (FUGR):** document each function module separately (`adt_get_source` with type function + group); shared TOP include for state. ### 2. Read with a checklist While reading, collect — don't paraphrase line by line: - **Entry points:** events (START-OF-SELECTION, user-commands), public methods, FM interfaces, selection screen parameters. - **Database touchpoints:** every table read (SELECT/JOIN) and **especially every write** (INSERT/UPDATE/MODIFY/DELETE, CALL FUNCTION ... IN UPDATE TASK). Writes are the risk register. - **External calls:** RFCs, BAPIs, file I/O (OPEN DATASET, GUI_*), HTTP, authority-checks, COMMIT/ROLLBACK placement. - **Configuration coupling:** hardcoded values, TVARV/Z-config table reads, sy-mandt/sy-sysid branching. - **Smells worth flagging:** SELECT in loops, missing authority checks before writes, swallowed exceptions, dead branches (`adt_grep_source` across the package helps find copy-paste siblings). ### 3. Map the blast radius - `adt_where_used` on the main object: who calls this? A "legacy" report called by 14 other programs is infrastructure, not legacy. - `adt_list_versions` / `adt_compare_versions`: when was it last touched, how actively does it change? (Stable-for-8-years and changed-monthly need very different documentation depth.) - Optional, NW 7.55+: one or two `adt_read_table` samples on its Z tables to show real data shapes (row counts, key examples) — ask before querying business data, and keep samples small. ### 4. Write the document Structure (trim sections that don't apply): ```markdown # <OBJECT> — <one-line purpose> ## What it does (3–6 sentences, business language) ## How it's triggered (jobs, transactions, callers — from where-used) ## Inputs / outputs (selection screen, interfaces, files, spool) ## Data (tables READ / tables WRITTEN — writes first, bold) ## Control flow (numbered happy path; branches that matter) ## External dependencies (RFCs, BAPIs, files, config tables) ## Risks & smells (each with file:line references) ## Change history signal (last N versions: who, when, what theme) ## Migration notes (S/4 readiness: deprecated statements, obsolete FMs — apply the abap-clean-core skill's levels if loaded) ``` Cite everything as `INCLUDE/METHOD:line` so the next developer can jump straight in. If the user wants the doc persisted, write it to a local markdown file named after the object. ### 5. Batch mode For "document the whole package": `adt_browse_package` to enumerate, then triage — document deeply only objects with DB writes or many callers; one-line summaries for trivial ones. State the triage rule in the output so nobody mistakes a one-liner for a full review.