diff --git a/.changes/work-items/feat-8328-decompose-daily-integration-6b1e4d9a.md b/.changes/work-items/feat-8328-decompose-daily-integration-6b1e4d9a.md
new file mode 100644
index 00000000000..b1f4de413bf
--- /dev/null
+++ b/.changes/work-items/feat-8328-decompose-daily-integration-6b1e4d9a.md
@@ -0,0 +1,7 @@
+---
+bump: minor
+---
+
+### Changed
+
+- `/work-items:decompose` window bar now also asks that a slice can merge to the mainline at least daily, as practice guidance on integration cadence; it sets no hours estimate and no day cap.
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/case.yaml b/plugins/work-items/evals/decompose-slice-checks-daily-integration/case.yaml
new file mode 100644
index 00000000000..d6e4b413ac2
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/case.yaml
@@ -0,0 +1,2 @@
+schema_version: "1.1"
+name: decompose-slice-checks-daily-integration
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/applies-window-bar.md b/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/applies-window-bar.md
new file mode 100644
index 00000000000..fcdfd48cef6
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/applies-window-bar.md
@@ -0,0 +1,14 @@
+---
+type: llm
+---
+
+The prompt asks for the four checks on a small draft vertical slice (a `--month` flag, its config
+key, the code path and a test, no other slice needed).
+
+PASS if the reply gives a verdict for the window bar saying the slice fits one fresh context window,
+states that the slice can also integrate (merge to the mainline) at least daily, and gives no hours
+estimate, time estimate or one-day cap.
+
+FAIL if the reply omits the daily-integration check, estimates the work in hours or days, sets a day
+cap, says the slice cannot integrate at least daily without reshaping it as the fix, or runs no
+window-bar check.
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/mentions-daily-integration.md b/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/mentions-daily-integration.md
new file mode 100644
index 00000000000..9ad86fead50
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/mentions-daily-integration.md
@@ -0,0 +1,5 @@
+---
+type: regex
+pattern: '(?<!\bnot\s)(?<!n''t\s)(?<!\bcannot\s)(?<!\bnever\s)\b(integrate[sd]?|integrating|integration|merg\w*)\s+(\w+\s+){0,5}?(at\s+least\s+daily|the\s+same\s+day|within\s+(a|one)\s+day)\b'
+flags: i
+---
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/no-hours-estimate.md b/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/no-hours-estimate.md
new file mode 100644
index 00000000000..dd0fff32cf4
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/graders/no-hours-estimate.md
@@ -0,0 +1,6 @@
+---
+type: regex
+pattern: '(?<!\bno\s)(?<!\bnever\s)(?<!\bnot\s)\b\d+(\.\d+)?[\s-]*(hours?|hrs?)\b'
+flags: i
+match: not_contains
+---
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/prompt.md b/plugins/work-items/evals/decompose-slice-checks-daily-integration/prompt.md
new file mode 100644
index 00000000000..a5a21ffdebb
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/prompt.md
@@ -0,0 +1,16 @@
+---
+description: "A vertical slice that fits one fresh context window is also checked for integrating at least daily, with no hours estimate"
+tags: [decompose, slice-size]
+runs: 3
+max_turns: 20
+timeout_seconds: 300
+allowed_tools: [Read, Glob, Grep, Skill]
+expected_outcome: "Applies the window bar to the draft slice, finds it fits one fresh context window, also states it can merge to the mainline at least daily, and gives no hours estimate or day cap"
+---
+
+Load /work-items:decompose and apply its four checks to this draft vertical slice. Report one line per
+check, then say what to do with the slice.
+
+Draft slice: "Add a `--month` flag to the refund export command, with the config key it reads, the
+code path that honors it, and a test that runs the command for one month." It touches three files and
+needs no other slice to run.
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/samples/mentions-daily-integration.json b/plugins/work-items/evals/decompose-slice-checks-daily-integration/samples/mentions-daily-integration.json
new file mode 100644
index 00000000000..f1fa1cb83d8
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/samples/mentions-daily-integration.json
@@ -0,0 +1,46 @@
+{
+  "pass": [
+    {
+      "answer": "Window bar: passes. One cold session finishes it in one fresh context window, and it can merge to the mainline at least daily.",
+      "why": "direct statement"
+    },
+    {
+      "answer": "Window bar: fits one window; the team can integrate at least daily. No estimate in hours or days is needed.",
+      "why": "negated hours mention"
+    },
+    {
+      "answer": "Window bar passes: it will merge at least daily as a thin slice.",
+      "why": "short form"
+    },
+    {
+      "answer": "Window bar: pass. A cold session can finish it in one fresh context window and merge it the same day.",
+      "why": "same-day merge meets the at-least-daily floor"
+    },
+    {
+      "answer": "Window bar: pass, thin enough to integrate within a day.",
+      "why": "within-a-day form"
+    }
+  ],
+  "fail": [
+    {
+      "answer": "",
+      "why": "empty run"
+    },
+    {
+      "answer": "Window bar: passes, one fresh context window. Split it only if it grows.",
+      "why": "no daily integration"
+    },
+    {
+      "answer": "Window bar: this slice cannot integrate at least daily, so split it.",
+      "why": "negated daily mention"
+    },
+    {
+      "answer": "Window bar: passes, about 3 hours of work; merge daily.",
+      "why": "bare 'daily' states no floor"
+    },
+    {
+      "answer": "Window bar: a cold session cannot merge it the same day, so split it.",
+      "why": "negated same-day mention"
+    }
+  ]
+}
diff --git a/plugins/work-items/evals/decompose-slice-checks-daily-integration/samples/no-hours-estimate.json b/plugins/work-items/evals/decompose-slice-checks-daily-integration/samples/no-hours-estimate.json
new file mode 100644
index 00000000000..6b93bb3794a
--- /dev/null
+++ b/plugins/work-items/evals/decompose-slice-checks-daily-integration/samples/no-hours-estimate.json
@@ -0,0 +1,34 @@
+{
+  "pass": [
+    {
+      "answer": "Window bar: one fresh context window; integrates at least daily.",
+      "why": "no estimate"
+    },
+    {
+      "answer": "There is no hours estimate and never a day cap; it merges at least daily.",
+      "why": "negated mentions"
+    },
+    {
+      "answer": "It stays a three-file slice, so it merges at least daily.",
+      "why": "a number without hours"
+    }
+  ],
+  "fail": [
+    {
+      "answer": "Window bar: roughly 4 hours of work, merges at least daily.",
+      "why": "hours estimate"
+    },
+    {
+      "answer": "Window bar passes: a 2-hour slice, integrate at least daily.",
+      "why": "hyphenated hours"
+    },
+    {
+      "answer": "Window bar: about 6 hrs; merges at least daily.",
+      "why": "hrs abbreviation"
+    },
+    {
+      "answer": "Window bar passes; budget 8 hours, merge at least daily.",
+      "why": "budgeted hours"
+    }
+  ]
+}
diff --git a/plugins/work-items/skills/decompose/SKILL.md b/plugins/work-items/skills/decompose/SKILL.md
index dc92a366a51..0edf838afff 100644
--- a/plugins/work-items/skills/decompose/SKILL.md
+++ b/plugins/work-items/skills/decompose/SKILL.md
@@ -68,7 +68,7 @@ slice that fails one before moving to the next:
 | One concern | The vertical slice serves a single concern. From a PLAN.md source, a phase becomes one vertical slice unless it mixes independent concerns | Split along the concerns |
 | End to end | Every layer the behavior needs, its tests included, is real in this vertical slice and none is stubbed for later. A vertical slice adding a retention setting, say, ships the config key, the cleanup job that honors it, and a test that runs the job | Add the missing layers, or narrow the behavior until it fits |
 | Proof on its own | After merge, someone can run or inspect it without any later vertical slice | Narrow it until they can |
-| Window bar | A session that starts cold, reads the brief, and finishes the vertical slice in **one fresh context window**. Judge this beside S/M/L, qualitatively; never set a token budget or a numeric window size | Split it |
+| Window bar | A session that starts cold, reads the brief, and finishes the vertical slice in **one fresh context window**, and it can merge to the mainline at least daily. Judge this beside S/M/L, qualitatively; never set a token budget, a numeric window size, a time estimate or a day cap. "At least daily" is practice guidance on integration cadence, the merge floor, not an estimate ([DORA, trunk-based development](https://dora.dev/capabilities/trunk-based-development/#how-to-implement-trunk-based-development), "How to implement trunk-based development"; [Fowler, Continuous Integration](https://martinfowler.com/articles/continuousIntegration.html#EveryonePushesCommitsToTheMainlineEveryDay), "Everyone Pushes Commits To the Mainline Every Day"; as of 2026-10-18, recheck when either page changes its daily-merge guidance) | Split it |
 
 When two cuts both pass, take the one with more, thinner vertical slices.