diff --git a/SKILL.md b/SKILL.md
index 65cc783..ec1a679 100644
--- a/SKILL.md
+++ b/SKILL.md
@@ -340,10 +340,14 @@ Leave any genuinely-unknown field blank — the SOP hides blank parameters, so a
 empty until filled. The full method for the second-source search is in
 `references/schlib_parameters.md`.
 
-Collect the values into a `params.json` and write them into the symbol:
+Write the **full parameter set** — the typeid template's engineering columns **plus** the SOP
+params above (see `references/schlib_parameters.md`). Collect your filled values into a
+`params.json` and pass `--typeid` so the writer guarantees every template column is present
+(blank where the datasheet is silent):
 
 ```bash
-python scripts/schlib_write.py --schlib <in>.SchLib --params params.json --out <stage>/<tag>/<sym>.SchLib
+python scripts/schlib_write.py --schlib <in>.SchLib --params params.json \
+    --out <stage>/<tag>/<sym>.SchLib --typeid <TYPEID>
 ```
 
 Deliver the resulting `.SchLib`; the engineer opens it in Altium once to confirm it loads, then
diff --git a/assets/CHANGELOG.xlsx b/assets/CHANGELOG.xlsx
index 2681c60..2f57f66 100644
Binary files a/assets/CHANGELOG.xlsx and b/assets/CHANGELOG.xlsx differ
diff --git a/references/schlib_parameters.md b/references/schlib_parameters.md
index 9b53436..b84b496 100644
--- a/references/schlib_parameters.md
+++ b/references/schlib_parameters.md
@@ -93,24 +93,35 @@ symbol's Library Ref (from `altium_refs.py`); omit it to apply to every componen
 }
 ```
 
+## The full parameter set (template + SOP)
+
+Every `.SchLib` should carry the **complete** parameter set for its part: the **typeid
+template's engineering columns** (all columns of that typeid's `template.xlsx` sheet except the
+internal bookkeeping ones — the tag `MPN_make_type`, `Skill Version`, `Template Version`, and the
+four `Library/Footprint Ref/Path` columns) **plus** the mandatory SOP params above. So a CER
+(ceramic MLCC) symbol gets `Capacitance(uF)`, `Tolerance`, `Voltage(V)`,
+`Dielectric(temp. Coefficient)`, `Operating Temp(°C)`, `Max operating temp(°C)`, `Package`,
+`Description`, `Manufacturer` from the template, alongside `Value`, `Manufacturer Part`,
+`Process`, `Vecmocon Part Code`, `ROHS`, `Datasheet`, and the second-source fields. Fill each
+from the datasheet; leave blank what the datasheet doesn't state.
+
 ## Writing them into the symbol
 
-Write the parameters straight into the `.SchLib`, producing a new file:
+Write the parameters straight into the `.SchLib`, producing a new file. Pass `--typeid` so the
+writer guarantees the whole template column set is present (blank where you didn't supply a
+value) — this is what keeps every symbol's parameter set complete and consistent:
 
 ```bash
-python scripts/schlib_write.py --schlib <in>.SchLib --params params.json --out <out>.SchLib
+python scripts/schlib_write.py --schlib <in>.SchLib --params params.json --out <out>.SchLib --typeid <TYPEID>
 ```
 
-`params.json` may carry a `"remove"` list (defaults to `["Manufacturer_Name",
-"Manufacturer_Part_Number"]`); those Ultra-Librarian defaults are stripped and the SOP params
-added. The script targets the component named in `"component"` (its Library Ref / storage name),
-or every component if omitted, and self-checks the output re-opens as a valid OLE. Deliver the
-resulting `.SchLib`, and have the engineer open it in Altium once to confirm it loads, then Save
-to Server with a revision note per the SOP.
-
-Scope note: the direct writer keeps a component's `Data` under Altium's 4096-byte mini-stream
-threshold in the common case; a very large parameter set (or an extremely long datasheet URL)
-can push it past that, at which point fall back to the `altium_params.py` DXP-script path.
+`params.json` carries your filled values (and may include a `"remove"` list — defaults to
+`["Manufacturer_Name", "Manufacturer_Part_Number"]`, the Ultra-Librarian duplicates that get
+stripped). The script targets the component named in `"component"` (its Library Ref / storage
+name), or every component if omitted, and self-checks the output re-opens as a valid OLE. It
+handles any parameter-set size — small sets stay in Altium's mini-stream, larger ones are written
+as a regular stream automatically. Deliver the resulting `.SchLib`; have the engineer open it in
+Altium once to confirm it loads, then Save to Server with a revision note per the SOP.
 
 Fallback (apply from inside Altium):
 
diff --git a/scripts/schlib_write.py b/scripts/schlib_write.py
index ffc952b..4730cd6 100644
--- a/scripts/schlib_write.py
+++ b/scripts/schlib_write.py
@@ -29,7 +29,7 @@ IMPORTANT: this writes Altium's own binary format from outside Altium. It is val
 re-open as a well-formed OLE with every other stream byte-identical, but ALWAYS open the result
 in Altium once to confirm it loads before relying on it.
 """
-import argparse, json, struct, sys, hashlib
+import argparse, json, os, struct, sys, hashlib
 import olefile
 
 FREESECT=0xFFFFFFFF; ENDOFCHAIN=0xFFFFFFFE; FATSECT=0xFFFFFFFD
@@ -42,6 +42,26 @@ def le32(b,o): return struct.unpack('<I',b[o:o+4])[0]
 def pad(b,n): return b+b'\x00'*((-len(b))%n)
 
 
+# ----------------------------------------------------------------- typeid template columns
+
+# Template columns that are internal library bookkeeping, NOT symbol parameters.
+NON_PARAM_COLS = {"MPN_make_type", "Skill Version", "Template Version",
+                  "Library Ref", "Library Path", "Footprint Ref", "Footprint Path"}
+
+
+def template_param_names(template_path, typeid):
+    """The symbol-parameter columns for a typeid = every column on that typeid's template sheet
+    EXCEPT the internal bookkeeping ones (the tag, the two version columns, and the four design
+    Ref/Path columns). These are the engineering parameters that belong on the symbol."""
+    import openpyxl
+    wb = openpyxl.load_workbook(template_path, read_only=True)
+    if typeid not in wb.sheetnames:
+        raise SystemExit(f"no template sheet for typeid '{typeid}'")
+    ws = wb[typeid]
+    return [ws.cell(1, c).value for c in range(1, ws.max_column + 1)
+            if ws.cell(1, c).value and ws.cell(1, c).value not in NON_PARAM_COLS]
+
+
 # ----------------------------------------------------------------- read the container
 
 def read_container(path):
@@ -118,16 +138,34 @@ def _rec_name(block):
     return t.split('|Name=')[1].split('|')[0] if '|Name=' in t else None
 
 
+def _patch_field(block, field, value):
+    """Replace |field=...| inside a length-prefixed text record, re-framing its 4-byte length.
+    Used to set the component's ComponentDescription in the RECORD=1 header."""
+    import re
+    text = block[4:-1].decode('latin-1')
+    if f"|{field}=" in text:
+        text = re.sub(rf"\|{re.escape(field)}=[^|]*", f"|{field}={value}", text, count=1)
+    elif text.startswith("|RECORD="):
+        text = text + f"|{field}={value}"
+    payload = text.encode('latin-1') + b'\x00'
+    return struct.pack('<I', len(payload)) + payload
+
+
 def edit_data(data, params, remove):
     """Return a new Data stream: drop `remove` params, drop any SOP-name params (re-added
-    fresh), keep everything else, then append the SOP params. Pins/graphics/tail untouched."""
+    fresh), keep everything else, then append the SOP params. Also mirror the `Description`
+    parameter into the component's ComponentDescription field (the Altium 'Description' shown in
+    the component properties). Pins/graphics/tail untouched."""
     leading, tail = _leading_text_records(data)
     sop_names=set(params)
+    desc = params.get("Description")
     kept=[]
     for blk in leading:
         nm=_rec_name(blk)
         if nm is not None and (nm in remove or nm in sop_names):
             continue                                   # drop UL duplicates + stale SOP copies
+        if desc is not None and blk[4:-1].startswith(b"|RECORD=1|"):
+            blk = _patch_field(blk, "ComponentDescription", desc)   # component Description field
         kept.append(blk)
     added=[_param_record(20+i, nm, val) for i,(nm,val) in enumerate(params.items())]
     return b''.join(kept)+b''.join(added)+tail
@@ -211,10 +249,20 @@ def rebuild(entries, content):
 
 # ----------------------------------------------------------------- driver
 
-def write_params(schlib, params_json, out):
+def write_params(schlib, params_json, out, typeid=None, template=None):
     component=params_json.get("component") or None
-    fields=params_json.get("parameters", {}) or {}
+    fields=dict(params_json.get("parameters", {}) or {})
     remove=params_json.get("remove", DEFAULT_REMOVE)
+
+    # If a typeid+template are given, guarantee the FULL template parameter set is written:
+    # every engineering column for that typeid becomes a symbol parameter (value from the
+    # params if provided, else blank). This is what makes every .SchLib carry the complete,
+    # consistent parameter set the template defines — not just whatever was hand-listed.
+    typeid = typeid or params_json.get("typeid")
+    template = template or params_json.get("template")
+    if typeid and template:
+        for name in template_param_names(template, typeid):
+            fields.setdefault(name, "")
     entries, paths, content = read_container(schlib)
 
     # target Data stream sid(s): a stream named 'Data' whose parent storage == component (or all)
@@ -253,8 +301,15 @@ def main():
     ap.add_argument("--schlib", required=True)
     ap.add_argument("--params", required=True)
     ap.add_argument("--out", required=True)
+    ap.add_argument("--typeid", help="component typeid; with --template, writes that typeid's "
+                                     "full template parameter set (blank where not provided)")
+    ap.add_argument("--template", help="path to template.xlsx (defaults to the skill's)")
     a=ap.parse_args()
-    write_params(a.schlib, json.load(open(a.params, encoding="utf-8")), a.out)
+    template = a.template
+    if a.typeid and not template:
+        template = os.path.join(os.path.dirname(__file__), "..", "assets", "template", "template.xlsx")
+    write_params(a.schlib, json.load(open(a.params, encoding="utf-8")), a.out,
+                 typeid=a.typeid, template=template)
 
 
 if __name__ == "__main__":