Split graph.rs (1744 LOC) and symbol_analyzer.rs (1609 LOC) to clear the 1000-LOC gate

[zackees]

Background

The 1000-LOC gate (PR #467, workflow .github/workflows/loc-gate.yml) currently fails on every PR because two files in the bloat-analysis tree are over the threshold:

File	LOC	Was added by
`crates/fbuild-core/src/symbol_analysis/graph.rs`	1744	#463 (back-ref graph) + #470 (bidirectional + dual-rank callees)
`crates/fbuild-build/src/symbol_analyzer.rs`	1609	#424 (initial analyzer) + #460 (cref) + #463 (graph integration) + #470 (markdown bidirectional + dual sub-table)

Both grew past the cap in #470 (forward-refs + dual-rank). The gate now flags every new PR red, even ones (like #471) that don't touch these files at all.

Proposed splits

`graph.rs` (1744 LOC) → 3-4 modules

• `graph/mod.rs` — public re-exports + `GraphNode` / `GraphEdge` / `NodeKind` / `EdgeDirection` / `Direction` types.
• `graph/config.rs` — `GraphConfig` + `GraphDepth` knobs.
• `graph/backward.rs` — the existing `BackrefGraph::build_with_index` BFS walker.
• `graph/forward.rs` — `walk_forward` + `CalleeCandidate` + `rank_callees_dual` (added feat(bloat): per-symbol forward refs + bidirectional graph + dual-rank sub-table #470).
• `graph/render.rs` — `to_dot`, `node_color`, `node_width`, `format_*_label`, escape/sanitize.
• (tests stay alongside the unit they exercise.)

`symbol_analyzer.rs` (1609 LOC) → 3-4 modules

• `symbol_analyzer/mod.rs` — re-exports + `AnalyzeConfig` + `analyze_elf` driver.
• `symbol_analyzer/objdump.rs` — `run_objdump_and_attribute` (feat(bloat): per-symbol forward refs + bidirectional graph + dual-rank sub-table #470) + the objdump subprocess wiring.
• `symbol_analyzer/markdown.rs` — `format_text_report`, `format_markdown_report`, `format_markdown_report_with_graphs`, `emit_backref_graph_section`, `emit_dual_callees_subtable`.
• `symbol_analyzer/sidecar.rs` — `write_sidecar_dot_files` + `SidecarOptions`.

Acceptance

• Both files under 1000 LOC.
• `fbuild bloat` / `fbuild symbols` / `fbuild bloat-diff` / `fbuild bloat graph` all still work (existing tests pass unchanged).
• Public API is unchanged — only internal module layout shifts; downstream callers (CLI handlers in `fbuild-cli/src/cli/{bloat_cmd,bloat_diff_cmd,symbols_cmd,graph_cmd}.rs`) keep their existing `use` paths via re-exports from the new `mod.rs`.

Why not in PR #471

PR #471 is a docs + regression-test PR for #417. Folding a 700-line refactor into it would balloon the diff for no review benefit. Splitting cleanly is its own follow-up.

🤖 Filed by Claude Code while triaging #471's CI.

[zackees]

Both files are now under the 1000-LOC gate:

• crates/fbuild-core/src/symbol_analysis/graph.rs (was 1744 LOC) → split by PR refactor(symbol_analysis): split graph.rs + fix rustdoc broken link #474 into:
  • graph/mod.rs (750)
  • graph/walker.rs (608)
  • graph/tests.rs (834)
• crates/fbuild-build/src/symbol_analyzer.rs (was 1609 LOC) → split by PR refactor(symbol_analyzer): split into mod/markdown/tests submodule #475 into:
  • symbol_analyzer/mod.rs (618)
  • symbol_analyzer/markdown.rs (505)
  • symbol_analyzer/tests.rs (611)

LOC gate on the latest CI run (PR #483) is green. Closing.