diff --git a/.env.example b/.env.example
index f74b416..0c6c8ba 100644
--- a/.env.example
+++ b/.env.example
@@ -23,11 +23,12 @@ ADMIN_IDS=
 # Only the twentyq module needs this. Leave blank to disable that command.
 GEMINI_API_KEY=
 
-# SOURCE_COMMIT (commit SHA) is auto-injected into the container at runtime by
-# Coolify and read at startup for the deploynotify owner DM — do NOT set it here
-# and do NOT declare it in docker-compose (that would clobber Coolify's value
-# with an empty string). Local `docker compose up` has none, so deploynotify
-# just stays silent.
+# SOURCE_COMMIT (commit SHA) is read at startup for the deploynotify owner DM.
+# Do NOT set it here. On Coolify (Docker Compose) it is a predefined variable
+# that reaches the container only because docker-compose.yml references it
+# (`SOURCE_COMMIT: ${SOURCE_COMMIT:-}`) — Coolify supplies the value via
+# --env-file. Local `docker compose up` has none, so deploynotify reports
+# "unknown".
 
 # ====================== Leave UNSET on self-host ==================
 # These are AWS-only. cmd/server reads secrets directly from the plain env
diff --git a/docker-compose.yml b/docker-compose.yml
index 54ece36..86b5072 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -16,11 +16,13 @@ services:
       ADMIN_IDS: ${ADMIN_IDS}              # CSV of admin Telegram user ids
       # --- Optional ---
       GEMINI_API_KEY: ${GEMINI_API_KEY}    # only the twentyq module needs it
-      # SOURCE_COMMIT (commit SHA, read at startup for the deploynotify owner DM)
-      # is auto-injected into the container by Coolify — do NOT declare it here.
-      # A `SOURCE_COMMIT: ${SOURCE_COMMIT:-}` entry resolves to "" at compose-parse
-      # time and would clobber Coolify's runtime value. Local `docker compose up`
-      # has no SOURCE_COMMIT, so deploynotify just stays silent there.
+      # SOURCE_COMMIT (commit SHA, read at startup for the deploynotify owner DM).
+      # For Docker Compose, Coolify passes predefined vars via --env-file for
+      # interpolation ONLY — the var reaches the container only if referenced
+      # here (per Coolify docs). The :- default keeps local `docker compose up`
+      # (where SOURCE_COMMIT is unset) quiet; on Coolify the real value wins, so
+      # deploynotify reports "unknown" only outside Coolify.
+      SOURCE_COMMIT: ${SOURCE_COMMIT:-}
       # Storage auto-selects mongodb because MONGO_URL is set — no KV_PROVIDER.
       # The in-process cron scheduler runs by default — no CRON_MODE.
       # PORT defaults to 8080 (internal health server) — omit unless overriding.
diff --git a/docs/deploy-coolify-selfhosted.md b/docs/deploy-coolify-selfhosted.md
index f0df31c..cfe4ef4 100644
--- a/docs/deploy-coolify-selfhosted.md
+++ b/docs/deploy-coolify-selfhosted.md
@@ -88,12 +88,14 @@ SSM/AWS lookup that fails with no AWS creds and bricks startup), `KV_PROVIDER`,
    bot token; a second poller gets HTTP 409, and a second in-process scheduler
    double-fires crons. Prefer **stop-first redeploys** so two containers never
    overlap near a cron time.
-5. **deploynotify commit SHA:** Coolify auto-injects `SOURCE_COMMIT` (a
-   predefined runtime env var) into the container, and the bot reads it at
-   startup to DM the owner the "new version" notice — no manual wiring, and do
-   **not** declare `SOURCE_COMMIT` in compose/env (a `${SOURCE_COMMIT:-}` entry
-   resolves to `""` at parse time and clobbers Coolify's value). Without it,
-   `deploynotify` stays silent (no crash) — but you lose that notification.
+5. **deploynotify commit SHA:** `SOURCE_COMMIT` is a Coolify predefined
+   variable. For Docker Compose, Coolify passes predefined vars via `--env-file`
+   for interpolation only, so the value reaches the container **only because
+   `docker-compose.yml` references it** (`SOURCE_COMMIT: ${SOURCE_COMMIT:-}`).
+   The bot reads it at startup and DMs the owner on every boot; outside Coolify
+   (local `docker compose up`) it is unset and the DM shows `unknown`. The
+   "Include Source Commit in Build" Coolify setting affects build args only and
+   is **not** needed for this runtime path.
 6. **Health check:** use Coolify's HTTP monitor against `GET /` (returns
    `text/plain` `miti99bot ok`). Do **not** use a compose `healthcheck` — the
    distroless image has no shell/curl and `cmd/server` has no `-healthcheck`