include .ssp document abstraction in source pod

- When --source/--pod is used, automatically generate the .ssp
  document abstraction and bundle it into the pod at
  media/abstraction/{doc_uid}.{lang}.ssp

- This makes show_abstraction implicitly true when source_or_pod
  is active, so the .ssp file is generated before the pod
  assembler runs (abstraction runs before outputHub, and
  source_or_pod is the first task in outputHub).

- Changes:
    paths_source.d:
      Add abstraction_root() path helper to _PodPaths struct,
      following the same pattern as image_root(). Produces
      paths like pod/media/abstraction/ for both zpod (inside
      zip) and filesystem_open_zpod (open directory).

    source_pod.d:
      - Create media/abstraction/ directory in
        podArchive_directory_tree
      - Bundle .ssp file in pod_zipMakeReady: reads from the
        abstraction output directory, copies to open pod
        directory, adds to zip archive, computes SHA-256 digest
      - Write .ssp digest in zipArchiveDigest alongside sstm
        and ssi digests

    spine.d:
      Make show_abstraction() return true when source_or_pod is
      active (previously only returned true for explicit
      --show-abstraction flag).

- The .ssp is always included when building pods - no exclusion
  flag for this experimental feature to keep things simple.
  Not generated for non-pod outputs (--text, --html, etc.)
  unless --show-abstraction is explicitly passed.

- Tested against all 35 sample documents - zero failures.

  Co-Authored-By: Anthropic Claude Opus 4.6 (1M context)

3 files changed, 51 insertions, 1 deletions

diff --git a/src/sisudoc/io_in/paths_source.d b/src/sisudoc/io_in/paths_source.d
index 9f8ae63..41353ed 100644
--- a/src/sisudoc/io_in/paths_source.d
+++ b/src/sisudoc/io_in/paths_source.d
@@ -821,6 +821,20 @@ template spinePathsPods() {
         }
         return _pods();
       }
+      auto abstraction_root(string fn_src) {
+        auto pod_root_ = pod_root(fn_src);
+        auto pth_1_ = ((media_root(fn_src).zpod.chainPath("abstraction")).asNormalizedPath).array;
+        auto pth_2_ = ((media_root(fn_src).filesystem_open_zpod.chainPath("abstraction")).asNormalizedPath).array;
+        struct _pods {
+          auto zpod() {
+            return pth_1_;
+          }
+          auto filesystem_open_zpod() {
+            return pth_2_;
+          }
+        }
+        return _pods();
+      }
       auto image_root(string fn_src) {
         auto pod_root_ = pod_root(fn_src);
         auto pth_1_ = ((media_root(fn_src).zpod.chainPath("image")).asNormalizedPath).array;
diff --git a/src/sisudoc/io_out/source_pod.d b/src/sisudoc/io_out/source_pod.d
index fa9794b..c77ce45 100644
--- a/src/sisudoc/io_out/source_pod.d
+++ b/src/sisudoc/io_out/source_pod.d
@@ -114,6 +114,9 @@ template spinePod() {
       if (!exists(pths_pod.css(doc_matters.src.filename).filesystem_open_zpod)) {
         pths_pod.css(doc_matters.src.filename).filesystem_open_zpod.mkdirRecurse;
       }
+      if (!exists(pths_pod.abstraction_root(doc_matters.src.filename).filesystem_open_zpod)) {
+        pths_pod.abstraction_root(doc_matters.src.filename).filesystem_open_zpod.mkdirRecurse;
+      }
       if (!exists(pths_pod.image_root(doc_matters.src.filename).filesystem_open_zpod)) {
         pths_pod.image_root(doc_matters.src.filename).filesystem_open_zpod.mkdirRecurse;
       }
@@ -179,6 +182,36 @@ template spinePod() {
           }
         }
       }
+    } { // bundle abstraction .ssp file
+      import sisudoc.io_out.paths_output;
+      auto out_pth = spineOutPaths!()(doc_matters.output_path, doc_matters.src.language);
+      string abstraction_dir = ((out_pth.output_base.chainPath("abstraction")).asNormalizedPath).array;
+      string ssp_filename = doc_matters.src.doc_uid_out ~ ".ssp";
+      string fn_src_in = ((abstraction_dir.chainPath(ssp_filename)).asNormalizedPath).array.to!string;
+      auto fn_src_out_pod_zip_base
+        = pths_pod.abstraction_root(doc_matters.src.filename).zpod.to!string
+        ~ "/" ~ ssp_filename;
+      auto fn_src_out_filesystem
+        = pths_pod.abstraction_root(doc_matters.src.filename).filesystem_open_zpod.to!string
+        ~ "/" ~ ssp_filename;
+      if (exists(fn_src_in)) {
+        debug(io) { writeln("(io debug) src out found: ", fn_src_in); }
+        { // take DIGEST write to pod file digests.txt
+          auto data = (cast(byte[]) (fn_src_in).read);
+          _digests[doc_matters.src.language]["ssp"] ~= data.sha256Of.toHexString
+            ~ "::" ~ data.length.to!string ~ " - " ~ ssp_filename ~ "\n";
+        }
+        if (doc_matters.opt.action.source_or_pod) {
+          fn_src_in.copy(fn_src_out_filesystem);
+        }
+        if (doc_matters.opt.action.source_or_pod) {
+          zip = podArchive("file_path_text", fn_src_in, fn_src_out_pod_zip_base, zip);
+        }
+      } else {
+        if (doc_matters.opt.action.debug_do_pod && doc_matters.opt.action.vox_gt_2) {
+          writeln("WARNING (io) src out NOT found (abstraction): ", fn_src_in);
+        }
+      }
     } { // bundle dr_document_make
       auto fn_src_in = ((doc_matters.src.is_pod)
         ? doc_matters.src.conf_dir_path
@@ -475,6 +508,9 @@ template spinePod() {
             // if (doc_matters.opt.action.vox_gt_2) { writeln(_digests[_lang]["ssi"]); }
             f.writeln(_digests[_lang]["ssi"]);
           }
+          if (("ssp" in _digests[_lang]) && (_digests[_lang]["ssp"].length > 0)) {
+            f.writeln(_digests[_lang]["ssp"]);
+          }
         }
       }
       if ("shared" in _digests) {
diff --git a/src/sisudoc/spine.d b/src/sisudoc/spine.d
index f7b7d66..0598ca7 100755
--- a/src/sisudoc/spine.d
+++ b/src/sisudoc/spine.d
@@ -503,7 +503,7 @@ string program_name = "spine";
       return opts["show-config"];
     }
     @trusted bool show_abstraction() {
-      return opts["show-abstraction"];
+      return (opts["show-abstraction"] || source_or_pod) ? true : false;
     }
     @trusted bool show_abstraction_db() {
       return opts["show-abstraction-db"];