diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
new file mode 100644
index 0000000..4c8ffbc
--- /dev/null
+++ b/.github/workflows/validate.yml
@@ -0,0 +1,20 @@
+name: validate
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  repository-contract:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - name: Run repository contract tests
+        run: python3 -m unittest discover -s tests -v
+      - name: Compile tests
+        run: python3 -m compileall -q tests
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..43ae0e2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+__pycache__/
+*.py[cod]
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..c7bc161
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,49 @@
+# Plotter Image Animations agent guide
+
+This repository is a Published Media Snapshot containing three checked-in MP4
+exports. Read `PROJECT.md` and `CONTEXT.md` before making changes.
+
+## Boundaries
+
+- Preserve every checked-in MP4 byte-for-byte unless a reviewed change
+  explicitly replaces the published snapshot.
+- Do not recompress, rename, regenerate, or remove media without identified
+  generating source, provenance, and publication-rights review.
+- Do not claim that the exports are reproducible while the source project is
+  unresolved.
+- Keep credentials, private machine paths, and raw secret-scan findings out of
+  committed files.
+- Tests must use the Python standard library and repository fixtures. They must
+  not publish media, register services, or mutate external systems.
+
+## Commands
+
+```bash
+python3 -m unittest discover -s tests -v
+python3 -m compileall -q tests
+gitleaks git --no-banner --redact
+```
+
+## Validation
+
+Run the complete unit suite and compile the Python tests before claiming the
+repository contract works. Verify media size and SHA-256 values rather than
+trusting filenames or visual similarity.
+
+## Agent skills
+
+### Issue tracker
+
+Issues and follow-up custody work live in GitHub Issues for
+`ReidSurmeier/plotter-image-animations`. See
+`docs/agents/issue-tracker.md`.
+
+### Triage labels
+
+Use the five standard Matt Pocock triage roles. See
+`docs/agents/triage-labels.md`.
+
+### Domain docs
+
+This is a single-context repository with `CONTEXT.md` at the root and decisions
+in `docs/adr/`. See `docs/agents/domain.md`.
diff --git a/CONTEXT.md b/CONTEXT.md
new file mode 100644
index 0000000..df5170f
--- /dev/null
+++ b/CONTEXT.md
@@ -0,0 +1,59 @@
+# Plotter Image Animations context
+
+## Purpose
+
+Preserve the known public animation exports and make their custody,
+reproducibility, publication, and deployment boundaries explicit.
+
+## Domain language
+
+### Published Media Snapshot
+
+A fixed set of rendered files preserved as public evidence. A snapshot can be
+validated byte-for-byte but is not automatically reproducible.
+
+### Animation Export
+
+One final MP4 in `animations/`. It is an immutable member of the current
+Published Media Snapshot.
+
+### Mark-build
+
+The progressive appearance of plotter-like marks in the left panel of each
+Animation Export.
+
+### Plate/Contact Sheet
+
+The static right-hand panel showing the component marks or printing plates that
+correspond to the animation.
+
+### Generating Source
+
+The project files, source imagery, transforms, scripts, dependencies, and
+export settings needed to reproduce an Animation Export. The Generating Source
+for this snapshot has not been located.
+
+### Publication Rights
+
+The documented authority to distribute the source imagery and derived
+Animation Exports. Public repository visibility is not proof of Publication
+Rights.
+
+### Deployment Owner
+
+The repository responsible for an active service, DNS route, Pages site, or
+other runtime. This snapshot has no Deployment Owner role because it has no
+runtime or deployment.
+
+## Invariants
+
+- The three Animation Exports retain their recorded byte sizes and SHA-256
+  hashes.
+- Missing Generating Source is stated as an unresolved custody fact.
+- Publication Rights are reviewed by a human before expanding distribution.
+- No runtime, Pages, Droplet, or Pugnet ownership is inferred from the presence
+  of public media.
+
+## Decision records
+
+- `docs/adr/0001-treat-mp4s-as-published-media-evidence.md`
diff --git a/PROJECT.md b/PROJECT.md
new file mode 100644
index 0000000..b85c546
--- /dev/null
+++ b/PROJECT.md
@@ -0,0 +1,72 @@
+# Project packet
+
+## Classification
+
+`plotter-image-animations` is a Published Media Snapshot. It preserves public
+rendered evidence; it is not a runnable application or a reproducible media
+pipeline.
+
+Verified on 2026-07-31 against the original `main` commit
+`348af448e71d53ab94a4aa6b4b6d4ad8b2204057`.
+
+## Verified contents
+
+The repository contains three silent 25-second MP4 exports. All are 1920x1080
+H.264 video with a white background, a progressive mark-build animation on the
+left, and a plate/contact sheet on the right.
+
+| Export | Frame rate | Bytes | SHA-256 |
+| --- | ---: | ---: | --- |
+| Portrait | 30 fps | 8,286,219 | `d0bb5232b30e8e1ecc57ff5229b1e5fd7a5746ce99d8d61da2fee447c4df040f` |
+| Bathroom | 25 fps | 3,097,091 | `a7bd0d91aface1ccf123401b1f10a253e24e26fa2b0d34811036c78268ba0676` |
+| Fashion | 30 fps | 9,713,253 | `fe4c716b0d7dd629b10a35f9ab874ee78413bcdce91557263f13b97f27c19a24` |
+
+The files are ordinary Git blobs, not Git LFS pointers. Their hashes and sizes
+are enforced by the repository contract test.
+
+## Custody and reproducibility boundary
+
+The generating source remains unresolved. A local inventory found no duplicate
+originals or project files that could regenerate these exact exports. The
+repository also lacks a source-image provenance record and an explicit
+publication-rights review.
+
+Until that evidence is recovered:
+
+- preserve the three MP4s byte-for-byte;
+- do not claim the exports are reproducible;
+- do not infer licenses or publication rights from public Git visibility; and
+- record newly recovered source as additive evidence before proposing changes
+  to the snapshot.
+
+## Runtime and deployment ownership
+
+There is no runtime. GitHub Pages is absent, the GitHub deployments list is
+empty, and the repository owns no Droplet or Pugnet process, container, systemd
+unit, DNS name, or public endpoint.
+
+The public GitHub repository itself is the current delivery surface for these
+files. A Release or archival publication surface may be considered only after
+source provenance and publication rights are resolved.
+
+## Validation
+
+```bash
+python3 -m unittest discover -s tests -v
+python3 -m compileall -q tests
+```
+
+The test suite checks the documentation contract and the exact published media
+bytes. Secret scanning and GitHub Actions provide additional repository gates.
+
+## Next decisions
+
+1. [Issue 1](https://github.com/ReidSurmeier/plotter-image-animations/issues/1):
+   locate and identify the generating project, source imagery, and export
+   process.
+2. [Issue 2](https://github.com/ReidSurmeier/plotter-image-animations/issues/2):
+   complete a human publication-rights review for the portrait, bathroom, and
+   fashion imagery.
+3. [Issue 3](https://github.com/ReidSurmeier/plotter-image-animations/issues/3):
+   decide whether GitHub Releases or another durable media surface should
+   supplement raw repository delivery after provenance is established.
diff --git a/README.md b/README.md
index 33fa7ff..4e73695 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,42 @@
 # Plotter Image Animations
 
-Public MP4 exports for three plotter mark-build image tests.
+Status: **Published Media Snapshot**
 
-## Files
+This repository preserves three public MP4 exports from plotter mark-build
+image tests. It does not contain the generating source, source images, or a
+reproducible export pipeline. Treat the checked-in media as published evidence,
+not as build output that can currently be regenerated.
 
-- `animations/01-portrait-markbuild-full-contact-25s.mp4`
-- `animations/02-bathroom-svg-reveal-25s.mp4`
-- `animations/03-fashion-markbuild-full-contact-25s.mp4`
+Deployment ownership: none. The repository is not an application, has no
+GitHub Pages site, and owns no Droplet or Pugnet service.
 
-Each file is a 1920x1080 white-background layout with the animation on the left and contact/plate sheet on the right.
+## Published media
+
+| File | Bytes | Video | SHA-256 |
+| --- | ---: | --- | --- |
+| `animations/01-portrait-markbuild-full-contact-25s.mp4` | 8,286,219 | 25 s, 1920x1080, H.264, 30 fps, silent | `d0bb5232b30e8e1ecc57ff5229b1e5fd7a5746ce99d8d61da2fee447c4df040f` |
+| `animations/02-bathroom-svg-reveal-25s.mp4` | 3,097,091 | 25 s, 1920x1080, H.264, 25 fps, silent | `a7bd0d91aface1ccf123401b1f10a253e24e26fa2b0d34811036c78268ba0676` |
+| `animations/03-fashion-markbuild-full-contact-25s.mp4` | 9,713,253 | 25 s, 1920x1080, H.264, 30 fps, silent | `fe4c716b0d7dd629b10a35f9ab874ee78413bcdce91557263f13b97f27c19a24` |
+
+Each export uses a white 1920x1080 layout: a progressive mark build appears on
+the left and a plate/contact sheet appears on the right. The subjects are a
+portrait, a bathroom scene, and a fashion image.
+
+Do not recompress, rename, or replace these files until the generating source
+and publication rights have been identified. Byte-level tests intentionally
+fail if the published snapshot changes.
+
+## Repository guide
+
+- [PROJECT.md](PROJECT.md) records the verified state, ownership boundary, and
+  unresolved custody work.
+- [CONTEXT.md](CONTEXT.md) defines the repository's domain language.
+- [AGENTS.md](AGENTS.md) gives contributor and validation instructions.
+- [`docs/adr/`](docs/adr/) records durable decisions.
+
+## Validate
+
+```bash
+python3 -m unittest discover -s tests -v
+python3 -m compileall -q tests
+```
diff --git a/context.toml b/context.toml
new file mode 100644
index 0000000..acb07fa
--- /dev/null
+++ b/context.toml
@@ -0,0 +1,24 @@
+schema_version = 1
+project = "plotter-image-animations"
+classification = "published-media-snapshot"
+context_document = "CONTEXT.md"
+project_document = "PROJECT.md"
+decision_directory = "docs/adr"
+issue_tracker = "github"
+deployment_ownership = "none"
+reproducible = false
+
+[[artifacts]]
+path = "animations/01-portrait-markbuild-full-contact-25s.mp4"
+bytes = 8286219
+sha256 = "d0bb5232b30e8e1ecc57ff5229b1e5fd7a5746ce99d8d61da2fee447c4df040f"
+
+[[artifacts]]
+path = "animations/02-bathroom-svg-reveal-25s.mp4"
+bytes = 3097091
+sha256 = "a7bd0d91aface1ccf123401b1f10a253e24e26fa2b0d34811036c78268ba0676"
+
+[[artifacts]]
+path = "animations/03-fashion-markbuild-full-contact-25s.mp4"
+bytes = 9713253
+sha256 = "fe4c716b0d7dd629b10a35f9ab874ee78413bcdce91557263f13b97f27c19a24"
diff --git a/docs/adr/0001-treat-mp4s-as-published-media-evidence.md b/docs/adr/0001-treat-mp4s-as-published-media-evidence.md
new file mode 100644
index 0000000..e1b2127
--- /dev/null
+++ b/docs/adr/0001-treat-mp4s-as-published-media-evidence.md
@@ -0,0 +1,34 @@
+# ADR 0001: Treat MP4s as published media evidence
+
+- Status: Accepted
+- Date: 2026-07-31
+
+## Context
+
+The repository contains three public MP4 exports but no generating project,
+source-image provenance, dependency record, or export instructions. The files
+can be inspected and verified byte-for-byte, but they cannot currently be
+regenerated from repository contents.
+
+Replacing or recompressing them would destroy the only local evidence of the
+published outputs. Conversely, describing them as reproducible would overstate
+what the repository proves.
+
+## Decision
+
+Treat the three MP4s as an immutable Published Media Snapshot:
+
+- record and test exact byte sizes and SHA-256 hashes;
+- preserve them without transformation;
+- state that Generating Source and Publication Rights remain unresolved; and
+- keep runtime and deployment ownership explicitly set to none.
+
+Recovered source or rights evidence must be added and reviewed before changing
+the snapshot or expanding its delivery surface.
+
+## Consequences
+
+The repository has a meaningful validation gate despite having no application
+runtime. Accidental binary replacement fails tests. Future contributors can
+distinguish published evidence from reproducible source, while follow-up work
+remains visible rather than being guessed into the documentation.
diff --git a/docs/agents/domain.md b/docs/agents/domain.md
new file mode 100644
index 0000000..e945c8b
--- /dev/null
+++ b/docs/agents/domain.md
@@ -0,0 +1,8 @@
+# Domain documentation
+
+The canonical domain model is `CONTEXT.md`. Use its terms in issues, commits,
+and decision records.
+
+Changes to the meaning of Published Media Snapshot, Animation Export,
+Generating Source, Publication Rights, or Deployment Owner require an ADR in
+`docs/adr/`.
diff --git a/docs/agents/issue-tracker.md b/docs/agents/issue-tracker.md
new file mode 100644
index 0000000..885437c
--- /dev/null
+++ b/docs/agents/issue-tracker.md
@@ -0,0 +1,8 @@
+# Issue tracker
+
+This repository uses GitHub Issues in
+`ReidSurmeier/plotter-image-animations`.
+
+Issues should identify the verified evidence, the unresolved custody or
+publication question, and the acceptance criteria. Never paste credentials,
+private paths, or raw secret-scan findings into an issue.
diff --git a/docs/agents/triage-labels.md b/docs/agents/triage-labels.md
new file mode 100644
index 0000000..fd25421
--- /dev/null
+++ b/docs/agents/triage-labels.md
@@ -0,0 +1,13 @@
+# Triage labels
+
+Use one of these role labels when work is ready to enter the corresponding
+state:
+
+- `needs-triage`: the issue needs classification or reproduction.
+- `needs-info`: additional evidence or a decision is required.
+- `ready-for-agent`: bounded implementation or research can proceed.
+- `ready-for-human`: judgment, authorship, rights, or visual review is needed.
+- `wontfix`: the issue is intentionally declined with a recorded reason.
+
+Move an issue between roles as its evidence and ownership change. Avoid using
+multiple role labels at once.
diff --git a/tests/test_repository_contract.py b/tests/test_repository_contract.py
new file mode 100644
index 0000000..a5396a4
--- /dev/null
+++ b/tests/test_repository_contract.py
@@ -0,0 +1,98 @@
+import hashlib
+import unittest
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+MEDIA = {
+    "animations/01-portrait-markbuild-full-contact-25s.mp4": (
+        8_286_219,
+        "d0bb5232b30e8e1ecc57ff5229b1e5fd7a5746ce99d8d61da2fee447c4df040f",
+    ),
+    "animations/02-bathroom-svg-reveal-25s.mp4": (
+        3_097_091,
+        "a7bd0d91aface1ccf123401b1f10a253e24e26fa2b0d34811036c78268ba0676",
+    ),
+    "animations/03-fashion-markbuild-full-contact-25s.mp4": (
+        9_713_253,
+        "fe4c716b0d7dd629b10a35f9ab874ee78413bcdce91557263f13b97f27c19a24",
+    ),
+}
+
+
+def read(relative_path: str) -> str:
+    return (ROOT / relative_path).read_text(encoding="utf-8")
+
+
+class RepositoryContractTests(unittest.TestCase):
+    def test_project_documentation_contract_exists(self) -> None:
+        required = (
+            "README.md",
+            "PROJECT.md",
+            "AGENTS.md",
+            "CONTEXT.md",
+            "context.toml",
+            "docs/adr/0001-treat-mp4s-as-published-media-evidence.md",
+            "docs/agents/domain.md",
+            "docs/agents/issue-tracker.md",
+            "docs/agents/triage-labels.md",
+            ".github/workflows/validate.yml",
+        )
+
+        self.assertEqual(
+            [path for path in required if not (ROOT / path).is_file()],
+            [],
+        )
+
+    def test_readme_states_the_media_snapshot_boundary(self) -> None:
+        text = read("README.md")
+
+        self.assertIn("Published Media Snapshot", text)
+        self.assertIn("does not contain the generating source", text)
+        self.assertIn("Deployment ownership: none", text)
+        self.assertIn("[PROJECT.md](PROJECT.md)", text)
+        self.assertIn("[CONTEXT.md](CONTEXT.md)", text)
+
+    def test_media_bytes_match_the_published_snapshot(self) -> None:
+        for relative_path, (expected_size, expected_sha256) in MEDIA.items():
+            path = ROOT / relative_path
+            digest = hashlib.sha256()
+            with path.open("rb") as handle:
+                while chunk := handle.read(1024 * 1024):
+                    digest.update(chunk)
+
+            self.assertEqual(path.stat().st_size, expected_size, relative_path)
+            self.assertEqual(digest.hexdigest(), expected_sha256, relative_path)
+            self.assertEqual(path.read_bytes()[4:8], b"ftyp", relative_path)
+
+    def test_project_packet_records_verified_media_and_unknown_provenance(self) -> None:
+        text = read("PROJECT.md")
+
+        self.assertIn("348af448e71d53ab94a4aa6b4b6d4ad8b2204057", text)
+        self.assertIn("three silent 25-second", text)
+        self.assertIn("1920x1080", text)
+        self.assertIn("H.264", text)
+        self.assertIn("generating source remains unresolved", text)
+        self.assertIn("GitHub Pages is absent", text)
+        self.assertIn("issues/1", text)
+        self.assertIn("issues/2", text)
+        self.assertIn("issues/3", text)
+
+    def test_active_contracts_do_not_embed_private_machine_paths(self) -> None:
+        private_home = "/" + "home/reidsurmeier"
+        paths = (
+            "README.md",
+            "PROJECT.md",
+            "AGENTS.md",
+            "CONTEXT.md",
+            "context.toml",
+            ".github/workflows/validate.yml",
+        )
+
+        for relative_path in paths:
+            self.assertNotIn(private_home, read(relative_path), relative_path)
+
+
+if __name__ == "__main__":
+    unittest.main()