diff --git a/.github/workflows/candidate.yml b/.github/workflows/candidate.yml
index e272be3..75ca4f3 100644
--- a/.github/workflows/candidate.yml
+++ b/.github/workflows/candidate.yml
@@ -66,8 +66,18 @@ jobs:
       - uses: ruby/setup-ruby@003a5c4d8d6321bd302e38f6f0ec593f77f06600 # v1
         with:
           ruby-version: "3.4"
-          bundler-cache: true
+          bundler-cache: ${{ github.server_url == 'https://github.com' }}
           working-directory: ruby-client
+      - name: Install candidate dependencies without the unavailable Gitea cache service
+        if: github.server_url != 'https://github.com'
+        working-directory: ruby-client
+        env:
+          BUNDLE_APP_CONFIG: ${{ runner.temp }}/opencode-ruby-fixture-bundle-config
+          BUNDLE_PATH: ${{ runner.temp }}/opencode-ruby-fixture-bundle
+        run: |
+          echo "BUNDLE_APP_CONFIG=$BUNDLE_APP_CONFIG" >> "$GITHUB_ENV"
+          echo "BUNDLE_PATH=$BUNDLE_PATH" >> "$GITHUB_ENV"
+          bundle install --jobs 4 --retry 3
       - id: client-sha
         name: Verify immutable Ruby candidate checkout
         env:
@@ -94,7 +104,7 @@ jobs:
           mkdir -p ../.compat-evidence
           bundle exec ruby ../ruby/opencode_ruby_fixture_contract.rb
       - name: Upload fixture evidence
-        if: always()
+        if: always() && github.server_url == 'https://github.com'
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: ruby-fixtures-${{ github.run_id }}-${{ github.run_attempt }}
@@ -102,6 +112,9 @@ jobs:
           include-hidden-files: true
           if-no-files-found: warn
           retention-days: 30
+      - name: State the Gitea evidence boundary
+        if: always() && github.server_url != 'https://github.com'
+        run: echo "Gitea executed the fixture contract, but this forge has no supported immutable artifact upload; generated JSON is transient and is not review evidence."
 
   lockstep-client-contract:
     needs: prepare
@@ -130,8 +143,18 @@ jobs:
       - uses: ruby/setup-ruby@003a5c4d8d6321bd302e38f6f0ec593f77f06600 # v1
         with:
           ruby-version: ${{ matrix.ruby }}
-          bundler-cache: true
+          bundler-cache: ${{ github.server_url == 'https://github.com' }}
           working-directory: opencode-rails
+      - name: Install candidate dependencies without the unavailable Gitea cache service
+        if: github.server_url != 'https://github.com'
+        working-directory: opencode-rails
+        env:
+          BUNDLE_APP_CONFIG: ${{ runner.temp }}/opencode-rails-${{ matrix.ruby }}-bundle-config
+          BUNDLE_PATH: ${{ runner.temp }}/opencode-rails-${{ matrix.ruby }}-bundle
+        run: |
+          echo "BUNDLE_APP_CONFIG=$BUNDLE_APP_CONFIG" >> "$GITHUB_ENV"
+          echo "BUNDLE_PATH=$BUNDLE_PATH" >> "$GITHUB_ENV"
+          bundle install --jobs 4 --retry 3
       - name: Verify immutable candidate checkouts
         env:
           EXPECTED_RUBY_SHA: ${{ needs.prepare.outputs.ruby_ref }}
@@ -168,7 +191,7 @@ jobs:
           mkdir -p ../.compat-evidence
           bundle exec ruby ../ruby/lockstep_client_contract.rb
       - name: Upload lockstep evidence
-        if: always()
+        if: always() && github.server_url == 'https://github.com'
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: lockstep-ruby-${{ matrix.ruby }}-${{ github.run_id }}-${{ github.run_attempt }}
@@ -176,8 +199,12 @@ jobs:
           include-hidden-files: true
           if-no-files-found: warn
           retention-days: 30
+      - name: State the Gitea evidence boundary
+        if: always() && github.server_url != 'https://github.com'
+        run: echo "Gitea executed the lockstep client contract, but this forge has no supported immutable artifact upload; generated JSON is transient and is not review evidence."
 
   exact-image-contract:
+    if: github.server_url == 'https://github.com'
     needs: prepare
     runs-on: ubuntu-latest
     strategy:
@@ -230,7 +257,7 @@ jobs:
           mkdir -p .compat-evidence
           bundle exec scripts/run_image_contract.sh
       - name: Upload exact-image evidence
-        if: always()
+        if: always() && github.server_url == 'https://github.com'
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: image-${{ matrix.id }}-${{ github.run_id }}-${{ github.run_attempt }}
@@ -238,3 +265,51 @@ jobs:
           include-hidden-files: true
           if-no-files-found: warn
           retention-days: 30
+
+  exact-image-contract-gitea:
+    if: github.server_url != 'https://github.com'
+    needs: prepare
+    runs-on: ubuntu-latest
+    name: Gitea full exact image matrix
+    steps:
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          repository: ajaynomics/opencode-ruby
+          ref: ${{ needs.prepare.outputs.ruby_ref }}
+          path: ruby-client
+      - uses: ruby/setup-ruby@003a5c4d8d6321bd302e38f6f0ec593f77f06600 # v1
+        with:
+          ruby-version: "3.4"
+      - name: Install candidate dependencies outside the checkout
+        working-directory: ruby-client
+        env:
+          BUNDLE_APP_CONFIG: ${{ runner.temp }}/opencode-ruby-bundle-config
+          BUNDLE_PATH: ${{ runner.temp }}/opencode-ruby-bundle
+        run: |
+          echo "BUNDLE_APP_CONFIG=$BUNDLE_APP_CONFIG" >> "$GITHUB_ENV"
+          echo "BUNDLE_PATH=$BUNDLE_PATH" >> "$GITHUB_ENV"
+          bundle install --jobs 4 --retry 3
+      - id: client-sha
+        name: Verify immutable Ruby candidate checkout
+        env:
+          EXPECTED_CLIENT_SHA: ${{ needs.prepare.outputs.ruby_ref }}
+        run: |
+          actual_client_sha="$(git -C ruby-client rev-parse HEAD)"
+          test "$actual_client_sha" = "$EXPECTED_CLIENT_SHA"
+          echo "value=$actual_client_sha" >> "$GITHUB_OUTPUT"
+      - name: Exercise the complete manifest matrix without artifact claims
+        env:
+          OPENCODE_RUBY_PATH: ${{ github.workspace }}/ruby-client
+          OPENCODE_RUBY_COMMIT: ${{ steps.client-sha.outputs.value }}
+          OPENCODE_RAILS_COMMIT: ${{ needs.prepare.outputs.rails_ref }}
+          OPENCODE_COMPAT_EVIDENCE_DIR: ${{ github.workspace }}/.compat-evidence
+          OPENCODE_COMPAT_RUN_ID: ${{ github.run_id }}
+          OPENCODE_COMPAT_RUN_ATTEMPT: ${{ github.run_attempt }}
+          OPENCODE_COMPAT_HEAD_SHA: ${{ github.sha }}
+          OPENCODE_COMPAT_REPOSITORY: ${{ github.repository }}
+          OPENCODE_COMPAT_RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+        run: scripts/run_image_matrix_contract.sh
+      - name: State the Gitea evidence boundary
+        if: always()
+        run: echo "Gitea executed every manifest image in one job, but this forge has no supported immutable artifact upload; generated JSON is transient and is not review evidence."
diff --git a/README.md b/README.md
index 7fc59b0..310cdaf 100644
--- a/README.md
+++ b/README.md
@@ -82,11 +82,16 @@ expected text byte-for-byte and the deterministic model stub to observe exactly
 one request and exactly one authoritative assistant message. It never calls an
 external model provider.
 
-Candidate CI uploads machine-readable fixture, lockstep-client, and exact-image
-evidence for 30 days. These artifacts are review inputs, not certification by
-themselves. A person must review a passing artifact and commit the durable
-certification document under `evidence/`; no workflow commits or promotes its
-own result.
+On GitHub, candidate CI uploads machine-readable fixture, lockstep-client, and
+exact-image evidence for 30 days. These artifacts are review inputs, not
+certification by themselves. Gitea runs the same repository, fixture, and
+lockstep contracts and executes every exact-image manifest entry sequentially,
+because its runner cannot expand a matrix from a dependency job's JSON output.
+The installed Gitea artifact service does not support the pinned GitHub upload
+action, so Gitea deliberately uploads nothing: its generated JSON is transient
+and must not be described as review evidence. A person must review a passing
+GitHub artifact and commit the durable certification document under `evidence/`;
+no workflow commits or promotes its own result.
 
 `manifests/image-matrix.json` binds the active pending matrix to both candidate
 commits. Its `previous_certification` entries preserve the last alpha7 result;
diff --git a/docs/certification.md b/docs/certification.md
index c730532..6d6c571 100644
--- a/docs/certification.md
+++ b/docs/certification.md
@@ -126,12 +126,16 @@ still does not certify a consumer's ActiveRecord schema, persistence callbacks,
 container adapter, or application canary; those remain consumer-owned profile
 evidence.
 
-CI writes canonical JSON artifacts for the shared fixture, lockstep client, and
-each exact-image target. Artifact retention is 30 days and supplies reviewable
-workflow provenance; it is not the long-term ledger. After review, copy the
-relevant facts into a repository evidence document bound to the complete tuple
-fingerprint. Automated workflows never update certified evidence or promote a
-tuple.
+GitHub CI writes canonical JSON artifacts for the shared fixture, lockstep
+client, and each exact-image target. Artifact retention is 30 days and supplies
+reviewable workflow provenance; it is not the long-term ledger. Gitea executes
+the same contracts, with its exact-image targets run sequentially from the full
+generated manifest, but its installed artifact service cannot accept the
+reviewed GitHub upload action. Gitea therefore keeps generated JSON transient
+and makes no artifact-evidence claim. After reviewing a GitHub artifact, copy
+the relevant facts into a repository evidence document bound to the complete
+tuple fingerprint. Automated workflows never update certified evidence or
+promote a tuple.
 
 The command clears `candidate` after promotion. It sets the repository-wide
 `migration_state` to `certified` only after every consumer has certified
diff --git a/scripts/run_image_matrix_contract.sh b/scripts/run_image_matrix_contract.sh
new file mode 100755
index 0000000..d1671eb
--- /dev/null
+++ b/scripts/run_image_matrix_contract.sh
@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+evidence_dir="${OPENCODE_COMPAT_EVIDENCE_DIR:-$repo_root/.compat-evidence}"
+matrix_json="$(ruby "$repo_root/scripts/matrix_json.rb")"
+entry_count="$(jq -er '.include | length' <<<"$matrix_json")"
+
+if [[ ! "$entry_count" =~ ^[1-9][0-9]*$ ]]; then
+  echo "exact image matrix must contain at least one entry" >&2
+  exit 2
+fi
+
+mkdir -p "$evidence_dir"
+
+for ((index = 0; index < entry_count; index++)); do
+  entry="$(jq -ec --argjson index "$index" '.include[$index]' <<<"$matrix_json")"
+  matrix_id="$(jq -er '.id' <<<"$entry")"
+  image="$(jq -er '.image' <<<"$entry")"
+  expected_version="$(jq -er '.version' <<<"$entry")"
+  required_profiles="$(jq -ec '.required_consumer_profiles' <<<"$entry")"
+  evidence_path="$evidence_dir/$matrix_id.json"
+
+  printf 'Running exact image matrix entry %s (%s)\n' "$matrix_id" "$image"
+  OPENCODE_IMAGE="$image" \
+  OPENCODE_EXPECTED_VERSION="$expected_version" \
+  OPENCODE_MATRIX_ID="$matrix_id" \
+  OPENCODE_REQUIRED_CONSUMER_PROFILES="$required_profiles" \
+  OPENCODE_COMPAT_EVIDENCE_PATH="$evidence_path" \
+    bundle exec "$repo_root/scripts/run_image_contract.sh"
+
+  jq -e \
+    --arg matrix_id "$matrix_id" \
+    --arg image "$image" \
+    --arg version "$expected_version" \
+    '.status == "pass" and
+      .matrix_target == $matrix_id and
+      .image.requested == $image and
+      .image.reported_version == $version' \
+    "$evidence_path" >/dev/null
+  printf 'Exact image matrix entry %s passed; JSON remains transient on this forge.\n' "$matrix_id"
+done
+
+printf 'Full exact image matrix passed (%s entries).\n' "$entry_count"
diff --git a/test/repository_test.rb b/test/repository_test.rb
index 7c47537..3a8e0c3 100644
--- a/test/repository_test.rb
+++ b/test/repository_test.rb
@@ -275,6 +275,35 @@ class RepositoryTest < Minitest::Test
     refute_match(/\b(kamal|kubectl|helm|nomad|docker\s+service|gh\s+pr\s+merge)\b/i, workflow)
   end
 
+  def test_candidate_workflow_has_an_explicit_dual_forge_evidence_boundary
+    workflow = File.read(File.join(ROOT, ".github/workflows/candidate.yml"))
+    upload_conditions = workflow.scan(
+      /- name: Upload (?:fixture|lockstep|exact-image) evidence\n\s+if: ([^\n]+)\n\s+uses: actions\/upload-artifact@/
+    ).flatten
+
+    assert_equal 3, upload_conditions.length
+    assert_equal ["always() && github.server_url == 'https://github.com'"], upload_conditions.uniq
+    assert_includes workflow, "bundler-cache: ${{ github.server_url == 'https://github.com' }}"
+    assert_includes workflow, "exact-image-contract-gitea:"
+    assert_includes workflow, "if: github.server_url != 'https://github.com'"
+    assert_includes workflow, "run: scripts/run_image_matrix_contract.sh"
+    assert_operator workflow.scan("generated JSON is transient and is not review evidence").length, :>=, 3
+
+    gitea_job = workflow.split(/^  exact-image-contract-gitea:\n/, 2).fetch(1)
+    refute_includes gitea_job, "actions/upload-artifact@"
+  end
+
+  def test_gitea_matrix_runner_uses_every_generated_entry_without_hardcoded_coordinates
+    runner = File.read(File.join(ROOT, "scripts/run_image_matrix_contract.sh"))
+
+    assert_includes runner, 'matrix_json="$(ruby "$repo_root/scripts/matrix_json.rb")"'
+    assert_includes runner, 'for ((index = 0; index < entry_count; index++))'
+    assert_includes runner, 'bundle exec "$repo_root/scripts/run_image_contract.sh"'
+    assert_includes runner, '.image.reported_version == $version'
+    refute_match(/upstream-[0-9]/, runner)
+    refute_match(/ghcr\.io\/anomalyco/, runner)
+  end
+
   def test_tuple_promotion_has_no_command_execution_or_deployment_client
     paths = %w[
       lib/opencode_compat/runtime_tuple_promoter.rb