diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6effb8fa..48345a07 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -124,6 +124,37 @@ jobs:
   # widening of this job.
   python:
     runs-on: ubuntu-latest
+    # Two numbers, because this job has two workloads and one flat cap has to
+    # be wrong for one of them.
+    #
+    # `sdk_parity` (declared above, `type: boolean, default: false`) is the
+    # whole difference: it switches on the planner byte-parity and
+    # planner-binding suites, which SKIP without an alp-sdk checkout -- 282 of
+    # 1163 tests. `release.yml:235` passes true; nothing else does.
+    #
+    #   PR / merge_group  6-11 min   measured across the last 25 successful
+    #                                runs (min 6m; p100 11m, run 32174278683)
+    #   release tag         23 min   run 31834718564, `v0.6.0-rc1`
+    #                                (1422s = 23.7m)
+    #
+    # A flat cap taken from the PR measurement passes every PR and then fails
+    # the tag, which is the most expensive place in this repo to be wrong. A
+    # flat 60 avoids that but leaves the >99% of runs that are PRs held for an
+    # hour against an 11-minute p100. The expression gets both: `inputs` is
+    # null on `pull_request`/`push`/`merge_group`, so `inputs.sdk_parity` is
+    # falsy there and this reads 30; on the `workflow_call` from release.yml it
+    # reads 60.
+    #
+    # 30 rather than 20 on the PR leg: p100 is 11m and trending up (the same
+    # trend visible on the release leg, 633s -> 1422s), so 20 is 1.8x headroom
+    # on a number that has moved. Both legs stay far under GitHub's own
+    # 360-minute default, which is what a hang catcher has to beat.
+    #
+    # NOTE for tan-cli#854, which generalises `parity.yml`'s timeout gate to
+    # every PR-triggered workflow: this value is a STRING expression, not an
+    # int. That gate's `isinstance(timeout, int)` assertion has to learn about
+    # expressions or it will red on this line.
+    timeout-minutes: ${{ inputs.sdk_parity && 60 || 30 }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
@@ -364,6 +395,9 @@ jobs:
   # Node's own test runner, so there is nothing to install.
   shim:
     runs-on: ubuntu-latest
+    # Under a minute on every run sampled, PR and release tag alike. 10 is a
+    # hang catcher for the pip install, not a budget.
+    timeout-minutes: 10
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
@@ -392,6 +426,8 @@ jobs:
   # measures.
   wheel-floor:
     runs-on: ubuntu-latest
+    # Under a minute on every run sampled. Same reasoning as `shim` above.
+    timeout-minutes: 10
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
@@ -465,6 +501,12 @@ jobs:
   workflow-security:
     name: zizmor · workflow security
     runs-on: ubuntu-latest
+    # This job's `name:` IS the fifth required context, and it was the one
+    # tan-cli#812 left unbounded while closing the other four (all of which
+    # come from parity.yml). A wedged run here holds the PR for GitHub's
+    # 360-minute default. Measured under a minute: pip install plus a
+    # hermetic `--no-online-audits` pass over .github/workflows/.
+    timeout-minutes: 10
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
diff --git a/.github/workflows/version-identity.yml b/.github/workflows/version-identity.yml
index 6059b53a..ae79128c 100644
--- a/.github/workflows/version-identity.yml
+++ b/.github/workflows/version-identity.yml
@@ -41,6 +41,10 @@ jobs:
   not-a-released-version:
     name: TAN_VERSION is not an existing tag's
     runs-on: ubuntu-latest
+    # A `fetch-depth: 0` checkout and one tag comparison -- measured under a
+    # minute (run 32046563751). The only unbounded job left in a
+    # PR-triggered workflow after ci.yml's four above (tan-cli#844).
+    timeout-minutes: 10
     steps:
       # fetch-depth: 0 — the whole point. `fetch-tags: true` with a shallow
       # fetch would also do, but 0 cannot be silently defeated by a future
diff --git a/changelog.d/844.fixed.md b/changelog.d/844.fixed.md
new file mode 100644
index 00000000..b615081f
--- /dev/null
+++ b/changelog.d/844.fixed.md
@@ -0,0 +1,31 @@
+- **No job in a PR-triggered workflow runs unbounded any more.** tan-cli#812
+  bounded `parity.yml`, which produces four of the five required contexts; the
+  fifth — `zizmor · workflow security`, the `name:` of `ci.yml`'s
+  `workflow-security` job — was still inheriting GitHub's 360-minute job
+  default, along with `ci.yml`'s `python`, `shim` and `wheel-floor` and
+  `version-identity.yml`'s `not-a-released-version`. A wedged leg on that fifth
+  context held the PR for six hours instead of failing in bounded time.
+
+  `ci.yml`: `python` 30 on a PR and 60 on the release call, `shim` 10,
+  `wheel-floor` 10, `workflow-security` 10. `version-identity.yml`:
+  `not-a-released-version` 10.
+
+- **`ci.yml`'s `python` job carries two caps, because it has two workloads.**
+  The same job measures 6-11 minutes on a `pull_request`/`merge_group` run
+  (last 25 successful runs; p100 11m, run `32174278683`) and **23.7 minutes**
+  on a release tag (run `31834718564`, `v0.6.0-rc1`, 1422s), because
+  `release.yml:235` calls this workflow with `sdk_parity: true` and that
+  switches on the planner byte-parity and planner-binding suites which SKIP
+  without an alp-sdk checkout — 282 of 1163 tests.
+
+  A flat cap taken from the PR measurement passes every PR and then fails the
+  tag, the most expensive place in this repo to be wrong; a flat 60 avoids that
+  but holds the >99% of runs that are PRs for an hour against an 11-minute
+  p100. `timeout-minutes: ${{ inputs.sdk_parity && 60 || 30 }}` gets both:
+  `inputs` is null on `pull_request`/`push`/`merge_group`, so the expression
+  reads 30 there and 60 on the `workflow_call` from `release.yml`. 30 rather
+  than 20 on the PR leg because the p100 is 11m and rising, the same trend the
+  release leg shows (633s → 1422s).
+
+  Note for whoever generalises `parity.yml`'s timeout gate (tan-cli#854): this
+  value is a string expression, not an int.