[sergo] Sergo Report: REGISTRY-GAP-43to67-doc-sync-closure-audit+manualpathconcat-2op-gap - 2026-08-30

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Executive summary

~7 weeks elapsed since the last Sergo run (2026-07-08 → 2026-08-30). The linter registry grew from 43 to 67 analyzers (24 new linters) and the registry's internal structure changed: cmd/linters/main.go is now a thin 24-line entrypoint (no longer a per-analyzer detector), replaced by pkg/linters/registry.go's allAnalyzers slice and a self-documenting header in pkg/linters/doc.go. This run split effort 50/50 between (a) re-validating previously-tracked bug classes against the new registry shape, and (b) exploring never-before-audited linters given the large registry growth. Filed 1 new issue: a coverage gap in manualpathconcat where a common 2-operand path-concatenation shape is never detected. Two historically major bug classes were confirmed permanently closed by new structural guardrails — details below.

Tool & registry updates

• Registry detector changed: use pkg/linters/doc.go's // All N active analyzers: header (N=67) or len(allAnalyzers) in pkg/linters/registry.go, not cmd/linters/main.go (now empty of per-analyzer lines).
• New self-enforcing test suite pkg/linters/doc_sync_test.go (4 tests) now cross-checks registry ↔ doc.go ↔ README ↔ .github/workflows/cgo.yml CI-enforcement list automatically. This permanently closes the doc-sync-drift and CI-enforcement-drift bug classes, previously the single most common finding type (e.g. doc-sync guard is incomplete: {registry, spec_test} and {doc.go, README} are two disconnected clusters — a linter present in cod [Content truncated due to length] #47190, doc-sync: pkg/linters/doc.go says "53 active analyzers" but 54 are registered — timenowsub is omitted #46707, trimleftright: the "repeated rune" cutset heuristic is an arbitrary discriminator that misses the most common TrimLeft/TrimRight [Content truncated due to length] #46526, doc-sync: pkg/linters/doc.go says "45 active analyzers" but 51 are registered — 6 newest linters omitted #46131, Registry-CI-enforcement drift: no automated guard ties linters.All() to cgo.yml LINTER_FLAGS #55628). No further probing of this class is warranted.
• The syntactic-package-match bug class (ident.Name == "pkg" instead of type-resolved matching) is now fully closed: a repo-wide grep for .Name (==|!=) "<stdpkg>" across pkg/linters returns zero matches. astutil.IsPkgSelector has been adopted universally.
• New shared abstraction pkg/linters/internal/resourcetracker centralizes the acquire-then-must-defer-cleanup state machine (nolint suppression, generated-file skip, diagnostic reporting) for contextcancelnotdeferred, manualmutexunlock, and fileclosenotdeferred. This run nearly mis-filed a suppression-gap issue against these three before reading the shared framework and confirming suppression is handled centrally — a false positive avoided.

Strategy split

50% cached reuse — re-applied proven audit methodology: registry-delta detection, gh api issue reconciliation before investigation (avoiding phantom/duplicate findings), and the pattern-set-too-narrow lens that has previously found real bugs in errstringmatch, sprintferrdot, and lenstringzero.

50% new exploration — audited linters with little or no prior Sergo history given the registry's growth to 67: nilctxpassed, bytesbufferstring, ioutildeprecated, globwalkignorederror, walkfuncerrshadow, goroutinemissingrecover. All were read in full and found clean/well-designed.

Success-metric targets set at strategy selection: ≥1 non-duplicate, well-evidenced finding; zero false-positive issues filed; explicit confirmation of the two previously-open bug-class closures.

Findings

manualpathconcat: 2-operand embedded-slash literal is never detected (filed as issue, see below)

matchSlashSeparator (manualpathconcat.go:120-137) only matches the 3-operand chain X + "/" + Y, requiring the middle operand to be the exact literal "/" (isSlashLiteral, line 140). The equally common 2-operand shape dir + "/subpath" — where the slash is embedded in a longer literal — is structurally unreachable: bin.X must itself be a *ast.BinaryExpr, which a bare identifier never is. The same gap exists in the += handler (analyzeAssignStmt, line 94). Testdata confirms zero coverage of this shape: goodSuffixOnly (dir + "/") and goodPrefixOnly ("/" + name) test different, narrower shapes. This is the same pattern_set_too_narrow class previously fixed in errstringmatch (#40244), sprintferrdot, and lenstringzero (#54717).

Audited and confirmed clean (no action needed)

• nilctxpassed — variadic/ellipsis-spread parameter handling correctly traced.
• bytesbufferstring — isBytesBufferValue correctly requires exact value type (not pointer), sound nil-semantics reasoning.
• ioutildeprecated — both qualified-selector and dot-import checks use types.Info resolution, not syntactic matching.
• globwalkignorederror, walkfuncerrshadow, goroutinemissingrecover — clean on full read.
• contextcancelnotdeferred / manualmutexunlock / fileclosenotdeferred — suppression correctly centralized in internal/resourcetracker; initial suppression-gap hypothesis was a false alarm, caught before filing.

Generated tasks / issues

ID	Title	Status
aw_sg61a1	manualpathconcat: 2-operand embedded-slash literal is never detected	Filed this run

Only 1 of the 3 available issue slots was used — the finding is well-evidenced and precise; consistent with this project's established preference for single-file precision over volume.

Metrics

• Findings this run: 5 (1 filed issue + 4 confirmed-clean audits + false-positive avoided)
• Tasks/issues created: 1
• Success score: 8/10 (solid, well-evidenced, non-duplicate finding; slightly reduced from historical average due to time spent re-deriving registry/tooling context after the 7-week gap rather than pure finding volume)
• Running totals: 61 runs, 413 cumulative findings, 110 cumulative tasks, avg success score 8.74

Historical context

This run closes out two bug-class categories that have recurred across many prior runs (doc-sync-drift and syntactic-package-match) — both are now structurally guarded by code rather than requiring ongoing manual audits. This mirrors the project's historical trend of previously-manual-audit classes becoming self-enforced over time (e.g. suppression/test-skip parity checks in earlier rounds).

Recommendations

• Stop allocating audit time to doc-sync-drift and syntactic-pkg-match classes — they are now structurally guarded.
• Prioritize the 24 linters added since the last run for first-time audits, since they carry no prior Sergo history and the registry has nearly grown 60%.
• When auditing any linter built on internal/resourcetracker, check the shared framework first — a single fix there would apply to all consumers at once.

Next-run focus (R62)

Re-check pkg/linters/doc.go's header count for further registry growth, then sweep remaining never-audited linters (hardcodedfilepath, sprintfbool, sprintferrdot, sprintferrorsnew, stringscountcontains, stringsindexhasprefix, timenowsub, trimleftright, uncheckedflushreturn, mapdeletecheck, logfatallibrary, httpstatuscode, excessivefuncparams) for pattern-set-too-narrow and autofix-compile-correctness issues, and verify aw_sg61a1 landed correctly.

References:

• §33290967014

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• expires on Aug 30, 2026, 8:01 PM UTC-08:00