chore: generate BuildInfo version, remove dead mirror tree, guard broadcast default

- Generate BuildInfo.version from version.value (dynver) so the JSON
  report's spark_lens_version can never drift from the published artifact;
  removes the hand-edited constant that was already stale (1.6.4 vs 1.6.5).
- Delete the dead mirrored src/ tree at the repo root: a full uncompiled
  duplicate of core/ + listener/ (excluded via unmanagedSourceDirectories
  := Nil) that had already drifted out of sync (Reporter.scala differed).
- Audited every config-reading analyzer for the AQE-class absent-key bug;
  none found. Added a JoinAnalyzer regression test pinning that an absent
  autoBroadcastJoinThreshold reads as Spark's 10 MB default, not disabled.

Author: nidhal-saadaoui

CHANGELOG.md

@@ -21,6 +21,19 @@ Versioning follows [Semantic Versioning](https://semver.org/).
   (mis-fired under default AQE) and `config-aqe-skew-disabled` (was silently suppressed
   when AQE was on by default). Added `minorVersion` helper to the `Analyzer` trait.
 
+### Internal
+- **`BuildInfo.version` is now generated from `version.value`** (dynver) at compile time
+  instead of being a hand-edited constant, so the `spark_lens_version` field in the JSON
+  report can no longer drift from the published artifact version.
+- **Removed the dead mirrored `src/` source tree** at the repo root. It was a full,
+  uncompiled duplicate of `core/` + `listener/` (excluded from the build via
+  `unmanagedSourceDirectories := Nil`) that had already drifted out of sync and was pure
+  maintenance risk. All compiled sources live in `core/`, `listener/`, and `testing/`.
+- Audited every config-reading analyzer for the same absent-key-misread class of bug the
+  AQE checks had; no further instances found (other checks use Spark's real defaults,
+  warn only on explicit misconfiguration, or require runtime evidence). Added a
+  regression test pinning `JoinAnalyzer`'s absent-`autoBroadcastJoinThreshold` behaviour.
+
 ---
 
 ## [1.6.5] — 2026-06-11

build.sbt

@@ -75,6 +75,22 @@ lazy val core = (project in file("core"))
       "org.slf4j"        %  "slf4j-api"  % "1.7.36"     % "provided",
       "org.scalatest"    %% "scalatest"  % "3.2.18"      % Test,
     ),
+    // BuildInfo.version is generated from version.value (dynver) so the version
+    // string in the JSON report can never drift from the published artifact.
+    // Do not check in a hand-written BuildInfo.scala — it will collide with this.
+    Compile / sourceGenerators += Def.task {
+      val file = (Compile / sourceManaged).value /
+        "com" / "github" / "saadaouini" / "sparklens" / "BuildInfo.scala"
+      IO.write(file,
+        s"""package com.github.saadaouini.sparklens
+           |
+           |/** Build-time constants — generated from build.sbt. Do not edit. */
+           |object BuildInfo {
+           |  val version = "${version.value}"
+           |}
+           |""".stripMargin)
+      Seq(file)
+    }.taskValue,
   )
 
 // ── listener: SparkLensListener + SparkAppModelBuilder ───────────────────────

core/src/main/scala/com/github/saadaouini/sparklens/BuildInfo.scala

@@ -24,6 +24,16 @@ class JoinAnalyzerSpec extends AnyFlatSpec with Matchers {
     issues.exists(_.id.startsWith("join-broadcast-disabled")) shouldBe false
   }
 
+  // Regression guard: sparkProperties only carries explicitly-set keys, so an absent
+  // autoBroadcastJoinThreshold must be read as Spark's real default (10 MB, broadcast
+  // ON), never as "disabled". Mirrors the AQE absent-config fix in ConfigAnalyzer.
+  it should "not flag broadcast disabled when the threshold is absent (Spark default 10 MB)" in {
+    val issues = JoinAnalyzer.analyze(app(
+      sqlExecs = Map(0L -> sqlExec(plan = SMJ_PLAN)),
+    ))
+    issues.exists(_.id.startsWith("join-broadcast-disabled")) shouldBe false
+  }
+
   it should "flag SortMergeJoin as Info when broadcast threshold is -1" in {
     val issues = JoinAnalyzer.analyze(app(
       sqlExecs = Map(0L -> sqlExec(plan = SMJ_PLAN)),