diff --git a/doc/manifest.md b/doc/manifest.md
new file mode 100644
index 0000000..5dc9bb2
--- /dev/null
+++ b/doc/manifest.md
@@ -0,0 +1,69 @@
+# String Manifest
+
+This document describes how to write a MetaGlot string manifest: the TOML file that
+declares the translatable strings of an application's metadata.
+
+The manifest is platform-neutral. It only describes *what* can be translated, not how
+translations end up in any particular platform format; MetaGlot reads it to produce
+Gettext translation catalogs and to fill platform-native output files. The file must
+be encoded in UTF-8.
+
+## Top-level fields
+
+| Field     | Type   | Description |
+|-----------|--------|-------------|
+| `version` | int    | The manifest format version. Currently `1`; any other value is rejected. |
+| `strings` | table  | All translatable strings. Each item maps a string entry key to a string entry, see below. |
+
+## String entry
+
+| Field     | Type   | Description |
+|-----------|--------|-------------|
+| `msgid`   | string | Required. The untranslated source string. |
+| `context` | string | Optional. Disambiguates entries that share the same `msgid` but are used differently, mirroring the context (`msgctxt`) mechanism of Gettext. Defaults to empty. |
+| `comment` | string | Optional. A note for translators explaining where and how the string is used. Defaults to empty. |
+
+The string entry key identifies the entry inside the manifest and in generated
+outputs. It must be non-empty; both numeric IDs (e.g. `1000`) and names
+(e.g. `file_description`) are acceptable, and numeric IDs are represented as strings.
+
+## Validation rules
+
+A manifest is rejected when:
+
+- `version` is not `1`.
+- Any string entry key is empty.
+- Two entries share both `msgid` and `context`.
+- An entry or the document root contains unknown fields.
+
+## Example
+
+```toml
+version = 1
+
+[strings.panel_title]
+msgid = "Example - Image Viewer"
+context = "Explorer"
+comment = "Shown by the file manager in the properties panel."
+
+[strings.file_type_jpeg]
+msgid = "JPEG Image"
+comment = "File type name for: jpg, jpeg, jfif"
+
+[strings.file_type_png]
+msgid = "PNG Image"
+comment = "File type name for: png"
+
+[strings.file_description]
+msgid = "Example - Image Viewer"
+context = "Self"
+comment = "File description of the executable."
+
+[strings.product_name]
+msgid = "Example"
+comment = "Display name of the product."
+```
+
+Note that entries `panel_title` and `file_description` share the same `msgid`. This
+is allowed because their `context` values differ; without distinct contexts the
+combination would be rejected as ambiguous.
diff --git a/src/metaglot/catalog.py b/src/metaglot/catalog.py
index 58ef6a8..0066bc9 100644
--- a/src/metaglot/catalog.py
+++ b/src/metaglot/catalog.py
@@ -1,51 +1,7 @@
 import glob
-import tomllib
 from pathlib import Path
 
 import polib
-from pydantic import BaseModel, ConfigDict, model_validator
-
-
-class StringEntry(BaseModel):
-    model_config = ConfigDict(extra="forbid")
-
-    msgid: str
-    context: str = ""
-
-
-class Manifest(BaseModel):
-    model_config = ConfigDict(extra="forbid")
-
-    strings: dict[str, StringEntry]
-
-    @model_validator(mode="after")
-    def _check_entries(self) -> "Manifest":
-        empty_keys = sorted(key for key in self.strings if not key)
-        if empty_keys:
-            raise ValueError("string key(s) must not be empty")
-        msgids = [entry.msgid for entry in self.strings.values()]
-        duplicated_msgids = sorted({msgid for msgid in msgids if msgids.count(msgid) > 1})
-        if duplicated_msgids:
-            raise ValueError(f"duplicated msgid(s): {', '.join(duplicated_msgids)}")
-        return self
-
-    @property
-    def entries(self) -> list[tuple[str, StringEntry]]:
-        return list(self.strings.items())
-
-    @property
-    def msgids(self) -> set[str]:
-        return {entry.msgid for entry in self.strings.values()}
-
-
-def load_manifest(path: Path) -> Manifest:
-    try:
-        raw = tomllib.loads(path.read_text(encoding="utf-8"))
-    except tomllib.TOMLDecodeError as exc:
-        raise ValueError(f"failed to parse manifest '{path}': {exc}") from exc
-    except OSError as exc:
-        raise RuntimeError(f"failed to read manifest '{path}': {exc}") from exc
-    return Manifest.model_validate(raw)
 
 
 def collect_po_files(patterns: list[Path]) -> list[Path]:
diff --git a/src/metaglot/manifest.py b/src/metaglot/manifest.py
new file mode 100644
index 0000000..6c405da
--- /dev/null
+++ b/src/metaglot/manifest.py
@@ -0,0 +1,64 @@
+import tomllib
+from pathlib import Path
+
+from pydantic import BaseModel, ConfigDict, field_validator, model_validator
+
+MANIFEST_VERSION = 1
+"""The manifest format version this build of MetaGlot understands."""
+
+
+class StringEntry(BaseModel):
+    model_config = ConfigDict(extra="forbid")
+
+    msgid: str
+    context: str = ""
+    comment: str = ""
+
+
+class Manifest(BaseModel):
+    model_config = ConfigDict(extra="forbid")
+
+    version: int
+    strings: dict[str, StringEntry]
+
+    @field_validator("version")
+    @classmethod
+    def _check_version(cls, value: int) -> int:
+        if value != MANIFEST_VERSION:
+            raise ValueError(
+                f"unsupported manifest version: {value} (expected {MANIFEST_VERSION})"
+            )
+        return value
+
+    @model_validator(mode="after")
+    def _check_entries(self) -> "Manifest":
+        empty_keys = sorted(key for key in self.strings if not key)
+        if empty_keys:
+            raise ValueError("string key(s) must not be empty")
+        pairs = [(entry.msgid, entry.context) for entry in self.strings.values()]
+        duplicated = sorted({pair for pair in pairs if pairs.count(pair) > 1})
+        if duplicated:
+            rendered = ", ".join(
+                f"{msgid!r}" if not context else f"{msgid!r} (context {context!r})"
+                for msgid, context in duplicated
+            )
+            raise ValueError(f"duplicated msgid and context combination(s): {rendered}")
+        return self
+
+    @property
+    def entries(self) -> list[tuple[str, StringEntry]]:
+        return list(self.strings.items())
+
+    @property
+    def msgids(self) -> set[str]:
+        return {entry.msgid for entry in self.strings.values()}
+
+
+def load_manifest(path: Path) -> Manifest:
+    try:
+        raw = tomllib.loads(path.read_text(encoding="utf-8"))
+    except tomllib.TOMLDecodeError as exc:
+        raise ValueError(f"failed to parse manifest '{path}': {exc}") from exc
+    except OSError as exc:
+        raise RuntimeError(f"failed to read manifest '{path}': {exc}") from exc
+    return Manifest.model_validate(raw)
diff --git a/src/metaglot/pot.py b/src/metaglot/pot.py
index 8c4677d..9ae8778 100644
--- a/src/metaglot/pot.py
+++ b/src/metaglot/pot.py
@@ -3,7 +3,7 @@ from pathlib import Path
 
 import polib
 
-from .catalog import Manifest, load_manifest
+from .manifest import Manifest, load_manifest
 
 _POT_HEADER = {
     "Project-Id-Version": "PACKAGE VERSION",
@@ -21,7 +21,14 @@ def generate(manifest_path: Path, output_path: Path) -> None:
     po = polib.POFile()
     po.metadata = _POT_HEADER
     for _, entry in manifest.entries:
-        po.append(polib.POEntry(msgid=entry.msgid, msgstr="", comment=entry.context))
+        po.append(
+            polib.POEntry(
+                msgid=entry.msgid,
+                msgstr="",
+                msgctxt=entry.context or None,
+                comment=entry.comment or None,
+            )
+        )
     output_path.parent.mkdir(parents=True, exist_ok=True)
     po.save(str(output_path))
     logging.info("wrote %d entries to %s", len(po), output_path)
diff --git a/src/metaglot/render.py b/src/metaglot/render.py
index 22cff8c..d469b81 100644
--- a/src/metaglot/render.py
+++ b/src/metaglot/render.py
@@ -5,7 +5,8 @@ from liquid import Environment, StrictUndefined
 from liquid.exceptions import LiquidError
 
 from . import winlang
-from .catalog import Manifest, collect_po_files, load_manifest, load_po
+from .catalog import collect_po_files, load_po
+from .manifest import Manifest, load_manifest
 
 
 def _rc_escape(value: str) -> str: