There are two planned key programs of the WFST 6-year survey: the Wide-field Survey (WFS) program and the Deep High-cadence $u$-band Survey (DHS) program. The different designed survey modes, in terms of survey depth, area and cadence, are commensurate with the primary scientific objectives of WFST. As part of the WFST 6-year survey, each program will occupy about 45% of the total observing time. The remaining $\sim$ 10% of the observing time (about 1,300 hours over 6 years) will be attributed to smaller campaigns for specific purposes, such as capturing time-critical targets and intensively scanning certain sky areas of particular interests (e.g. the Galactic plane).

The WFS program will cover an area of $\sim$ 8,000 deg$^2$ in the northern sky. It will employ four broad bands ($u, g, r, i$) with a single exposure of 30 seconds, leading to about 90 visits per pointing in each band over 6 years, if a clear night fraction of 70% at Lenghu site is assumed. As for the purpose of long-term monitoring of specific targets (e.g. active galactic nuclei and variables), single-band visits will be evenly distributed in 6 years, i.e. 60 multi-band visits (15 visits $\times$ 4 bands) per pointing per year, yielding yearly raw data of about 100 TB from the entire WFS fields. Observations for about 300 different pointings ($\sim$2,000 deg$^2$) with 60 visits per pointing will be executed throughout WFS during three months, leading to about 1,200 pointings in total every year. All of $u$-band observations are scheduled in dark and grey nights, in view of the highly sky background-sensitive measurements planned in this band. To balance the survey efficiency and science goals, and to optimize the homogeneity of WFS visits, we will avoid consecutive observation in a single band, but will observe in two bands every night, with the sole exception of $u$ band. This strategy will result in a reasonable cadence and time span in characterizing multi-band light curves for general purposes of time-domain research (e.g. transient classifications, variability statistics, and time-domain cosmology). Meanwhile, total integration in each band will reach $\sim 45$ min over 6 years, achieving deeper detection than any of the existing single-telescope surveys with comparable survey areas on the northern hemisphere.

In addition to WFS, we plan for the Deep High-cadence $u$-band Survey (DHS) program by virtue of the superior $u$-band imaging performance of WFST in time-domain investigations. DHS will routinely monitor a sky area of $2~\times \sim360$ deg$^2$ surrounding the equator every year (the ‘‘Spring’’ and ‘‘Autumn’’ fields; 6 months observing per each). Considering the importance of $u$-band imaging and color information in revealing the nature of various energetic transient phenomena, for each 6-months campaign of DHS, we perform photometry in at least one more band besides $u$ in hour cadence in consecutive $\pm$ 7 days during every lunar cycle (starting from the new moon). Meanwhile, a multi-band ancillary survey will keep monitoring the same region in the remaining nights of these 6 months. Such an innovative survey mode provides a unique opportunity to track transients right after their occurrences and to discover rare energetic explosive phenomena in the universe (e.g. early-phase supernovae, fast blue optical/ultraluminous transients, tidal disruption events, kilonovae, etc.). WFST will also be combined with the next-generation Chinese space missions (e.g. the Einstein Probe (EP); the Chinese Space Station Telescope (CSST)) to be launched in the upcoming years, so that unprecedented synchronization of multi-wavelength surveys between ground-based and space-borne wide-field survey facilities becomes feasible. By coordinating with EP and CSST, we will not only promptly identify optical counterparts of various high-energy astronomical events, but also attain real-time spectral energy distributions of various fast transients, by virtue of the anticipated synchronization and synergy.