Full flow demo

Full-Flow Demo: RTL -> Sim -> Synth -> Impl -> Bitstream

You are orchestrating a complete FPGA build. Your job is sequencing and gating, not problem-solving. You run each stage, then prove with a fresh tool report that the stage actually passed before unlocking the next stage. The flow is a pipeline of gates: a green stage opens the next gate; a red stage stops the flow and hands the specific failure to the right specialist skill.

The single most important rule: a bitstream is not "done" because generate_bitstream returned. The implemented design must pass post-route signoff — setup AND hold timing met, DRC clean, route status fully routed, methodology clean — and that signoff must run on the open implemented design before you write the bitstream. Synthesis numbers are necessary but never sufficient.

---

When to use

• User wants a design taken from source files all the way to a .bit (or .xsa / .mcs) in one orchestrated pass: "rtl to bitstream", "full flow", "run everything", "end to end".
• You have (or will create) a Vivado project with sources, constraints, and a known top module and target part.
• The user wants stage-by-stage gating and a final signoff summary they can trust, rather than a single black-box run_full_flow call.

When NOT to use

• A single stage is the actual problem. If the user says "fix my timing", "why does synthesis fail", "is my CDC clean", "my sim is wrong" — go straight to the specialist skill (timing-closure, synthesis-debug, cdc-analysis, simulation-debug, lint). This skill calls into those; it does not replace them.
• No project / no Vivado connection yet. Resolve prerequisites first.
• The design is a Block Design / Zynq / MPSoC system that has not yet been validated, generated, and wrapped. Do the BD bring-up first (bd_validate_design -> bd_generate_output_and_wrapper -> set_top_module <wrapper>), then return here for synth -> bitstream.
• The user wants speed over safety ("just slam it through, I don't care about checks"). You may use run_full_flow as a fast path, but you must still run the post-route signoff gate (Stage 5) before claiming success. Never skip that gate.

---

Prerequisites (verify first)

Run these before touching the flow. Do not assume; confirm with tool output.

1. MCP / Vivado / Tcl server alive — test_connection. If it fails, stop and tell the user to open Vivado and start tcl_server.tcl (TCP:9999). Nothing below works without this.
2. A project is open with a known target part — get_project_info. Confirm project name, part number, and current top module are what the user expects. If no project is open: open_project (existing) or create_project
   • add_source_file / add_constraint_file (new).
3. Top module is set and correct — confirm via get_project_info; fix with set_top_module if wrong. A wrong top silently synthesizes the wrong thing.
4. Sources and constraints are present and in order — list_source_files, list_constraint_files. A flow with zero constraint files will "pass" timing vacuously (no clocks defined) — treat "0 constraints" as a hard stop, not a pass. If compile order is suspect, check_compile_order.
5. License tier permits the full flow — get_license_status. Async runs, advanced reports, and some IP/BD tools are PRO/MAX. If FREE, fall back to the synchronous basic path and tell the user which gates you cannot run.

Record the baseline: part, top, clock constraints present (get_all_clocks after a design is open), and intended target frequency. You will measure the final result against this.

---

Methodology (numbered, gated)

Run stages in order. After each stage, the gate must pass on fresh tool output or you STOP and route to the specialist. One stage at a time so cause -> effect stays attributable.

Stage ordering is signoff-before-bitstream. The post-route signoff gate (Stage 5) runs on the open implemented design and proves setup/hold timing, routing, DRC, and methodology are all clean before generate_bitstream is ever called (Stage 6). You never write a bitstream on an unverified implemented design. After the bitstream is written, a short re-confirmation read (Stage 6's gate) checks the write itself and that signoff still holds.

Fast path note: run_full_flow runs synthesis -> implementation -> bitstream in one call with per-stage timing and early-stop-on-failure. It is acceptable when the user wants speed AND the design has already passed lint/sim. It does not replace the post-route signoff gate. Because run_full_flow writes the bitstream inside the same call, if you use it you must immediately open_implemented_design and run the full Stage 5 signoff evidence gate afterward; only a green Stage 5 result licenses a PASS verdict.

Stage 0 — Static checks (cheap, before any long run)

Catch dumb errors before burning minutes on synthesis.

• check_syntax (or check_syntax_file per file) — must be clean.
• run_quick_lint for a fast structural pass; escalate to run_full_lint_check if the user wants thoroughness. Triage with get_lint_violations.
• Targeted structural checks as relevant: check_latches (unintended latches), check_async_reset, check_fsm, check_port_width_mismatch, check_unconnected_ports, check_black_box.

GATE 0: No syntax errors. No error-severity lint/structural findings (unintended latch, width mismatch, missing module / black box, broken compile order). Warnings may pass with a noted assumption.

• If it fails: STOP. Hand to the lint skill. Do not waive_lint_violation or disable_lint_rule to make the count go green — see Safety rails.

Stage 1 — Functional simulation (does the RTL do the right thing?)

Synthesizing functionally-broken RTL wastes an hour. Simulate first when a testbench exists.

• Confirm the TB: list_simulation_files; set the sim top with set_simulation_top if needed.
• Compile: sim_compile (pass top_module). On failure read sim_get_compile_log.
• Run. Multi-minute sims: use the async pattern — sim_run_async, then poll sim_get_sim_status until COMPLETED (or sim_stop to abort). Short sims: sim_run.
• Read results with sim_get_report. Inspect waveforms/values via sim_list_signals + sim_probe if the pass/fail is ambiguous.

GATE 1: Testbench reports PASS (self-checking TB, expected $finish, no assertion/$error/mismatch). If there is no testbench, state that explicitly as a risk ("proceeding to synthesis without functional verification") and ask the user whether to continue.

• If it fails: STOP. Hand to the simulation-debug skill. A failing sim is an RTL bug; do not "fix" it by changing constraints downstream.

Stage 2 — CDC sanity (before committing to a build)

Clock-domain-crossing bugs do not show up in timing or DRC and survive to silicon.

• check_cdc_lint as an early RTL-level pass. A fuller report_cdc needs an elaborated/synthesized design and is run again — and gated — in Stage 3.

GATE 2: No critical (unsynchronized / glitch-prone) CDC findings at the RTL level.

• If it fails: STOP. Hand to the cdc-analysis skill. Do not set_false_path across a crossing to silence it unless you can state the assumption that it is genuinely async-safe and the user agrees — silencing a real CDC is a fake-pass.

Stage 3 — Synthesis

• (Optional) pick a strategy with set_synthesis_strategy — default is fine for a first pass; smallest change first.
• Run. Multi-minute: async — run_synthesis_async, poll get_run_status until the synth run STATUS shows complete (watch PROGRESS reach 100%). Short: run_synthesis.
• Open the result for analysis: open_synthesized_design.
• Evidence: get_synthesis_report, get_synthesis_warnings, check_synthesis_issues (needs the design open). Confirm clocks exist: get_all_clocks. Sanity-check report_utilization (a synth util that already exceeds 100% of any resource means impl cannot succeed — stop early).
• Re-run report_cdc now that there is a real netlist — synthesis can introduce or expose crossings the RTL-level check_cdc_lint did not see.

GATE 3: All of the following on fresh output:

• Synth run COMPLETE (not ERROR), no error-level synth warnings.
• At least one clock constraint present (get_all_clocks non-empty).
• Utilization physically fits the part (report_utilization under 100% on every resource).
• Post-netlist CDC clean — report_cdc shows no critical / unsafe (unsynchronized, glitch-prone, fan-out) crossings. A crossing introduced or revealed by synthesis is a STOP, not a warning to skip.

Post-synth timing is indicative only — do not claim "timing met" here.

• If it fails: STOP. Synth errors -> synthesis-debug skill. Post-netlist CDC findings -> cdc-analysis skill. Util overflow -> tell the user the design does not fit this part (architectural, not a constraint fix).

Stage 4 — Implementation (opt -> place -> route)

• (Optional) set_implementation_strategy (e.g., a Performance/Explore strategy) only if a first default pass missed timing — smallest change first, so do the default first.
• Run. Almost always multi-minute: async — run_implementation_async, poll get_run_status until impl_1 STATUS shows route_design Complete. Short designs: run_implementation.
• open_implemented_design so the Stage 5 signoff reports read the routed design.

GATE 4: Impl run COMPLETE (route_design did not error or abort).

• If it fails to route / errors: STOP. Capture get_implementation_warnings and report_congestion; route placement/congestion/timing-driven-routing failures to the timing-closure skill (it owns strategy/floorplan/RTL remediation). Do not blindly bump strategies in a loop.

Stage 5 — Post-route SIGNOFF gate (the gate that licenses "done") — runs BEFORE the bitstream

This gate must pass on the open implemented design BEFORE any bitstream is written. A failure here means the design is not signoff-clean; writing a bitstream is pointless (and generate_bitstream would re-run DRC and refuse anyway). Run on the open implemented design (open_implemented_design) with fresh reports:

• Timing: extract_timing_metrics (WNS/TNS/WHS/THS, failing endpoints) — you need both setup (WNS/TNS) and hold (WHS/THS) numbers across all clock groups. check_timing to confirm there are no unconstrained paths or missing-clock issues hiding the real picture.
• Routing: report_route_status — design must be 100% routed, zero unrouted nets.
• DRC: report_drc — zero error/critical violations. (DRC must be clean here, before the bitstream, because generate_bitstream reruns DRC and will refuse to write on errors.)
• Methodology: report_methodology — no critical methodology warnings (these flag CDC/timing-exception abuse the other reports miss).
• (Recommended) Power: report_power for a thermal/budget sanity number.

GATE 5 (signoff): ALL of the following must be true simultaneously on fresh post-route output, or you STOP:

• Setup met on every clock group: WNS ≥ 0 (equivalently TNS = 0).
• AND hold met on every clock group: WHS ≥ 0 (equivalently THS = 0). Setup-clean does not excuse a hold failure and vice-versa — both must pass at the same time.
• AND route status is 100% routed (zero unrouted nets).
• AND DRC clean (no error/critical violations).
• AND methodology clean (no critical warnings).

Only when every one of these is green on fresh output may you proceed to write the bitstream.

• If timing fails (setup OR hold < 0): STOP. Hand to the timing-closure skill with the extract_timing_metrics / analyze_critical_paths evidence. Do not set_false_path / set_multicycle_path to clear a real violation.
• If DRC/methodology fails: STOP and surface the specific rule IDs. Do not waive without an explicit user-approved assumption.

Stage 6 — Bitstream generation + final re-confirmation

Reach this stage only after Stage 5's signoff gate is fully green. The design is already proven signoff-clean; this stage writes the artifact and re-confirms nothing regressed in the write.

• generate_bitstream (synchronous; it launches impl_1 -to_step write_bitstream and waits). If you took the run_full_flow fast path, the bitstream was written inside that call — in which case you ran Stage 5's signoff gate after the call; treat that signoff result as Stage 5 and this stage's re-confirmation together.

GATE 6 (write + re-confirm):

• Bitstream write reported success and a .bit path is returned.
• A final read still shows the implemented design signoff-clean: re-confirm with report_route_status (still 100% routed) and report_drc (still 0 errors) on the open implemented design. (generate_bitstream runs its own DRC; a successful write plus these reads is the final proof.)
• If the write fails (e.g., DRC blocks it): STOP. This is a real signoff failure — return to Stage 5's DRC handling, not a workaround. (This should be rare, since Stage 5 already verified DRC.)

Stage 7 — Handoff artifacts (only after Gate 6 is green)

Produce what the user actually asked for:

• Program a board now: open_hardware_manager -> connect_hardware_server -> open_hardware_target -> program_device.
• Hand to embedded/Vitis (Zynq/MPSoC): export_hardware (include_bitstream=True) -> .xsa.
• Flash boot: generate_mcs / program_flash / add_flash_configuration.

---

Decision table — failed gate -> cause -> safe action -> owner

Failed gate	Likely cause	Smallest safe action	Hand off to
0 syntax/lint	Typo, latch, width/port mismatch, black box, compile order	Report violations; recommend RTL/file-order fix (do not waive)	lint skill
1 simulation	Functional RTL bug	Report failing TB checks via sim_get_report/sim_probe	simulation-debug skill
2 CDC (RTL)	Unsynchronized async crossing	Report check_cdc_lint findings; recommend synchronizer	cdc-analysis skill
3 synth error	Unsupported construct, missing file/param	get_synthesis_warnings, check_synthesis_issues; recommend RTL fix	synthesis-debug skill
3 CDC (netlist)	Crossing introduced/exposed by synthesis	Report report_cdc findings; recommend synchronizer	cdc-analysis skill
3 util overflow	Design too big for part	Report report_utilization; this is architectural, not a constraint	user (part/arch decision)
3 no clocks	Missing/empty XDC	Add real create_clock_constraint; never proceed with 0 clocks	user / constraints author
4 route fail / congestion	Routing/placement pressure	report_congestion; try ONE stronger impl strategy, else escalate	timing-closure skill
5 timing (WNS or WHS < 0)	Real setup or hold failure	extract_timing_metrics+analyze_critical_paths; constraints/strategy before RTL	timing-closure skill
5 route not 100%	Unrouted nets	report_route_status; congestion/strategy via timing-closure	timing-closure skill
5 DRC	Real rule violation (IO, config, etc.)	Report rule IDs from report_drc; fix root cause	user (confirm before any waiver)
5 methodology	Exception/CDC abuse	Report report_methodology; remove improper exceptions	cdc-analysis / timing-closure
6 bitstream write blocked	DRC regression at write	Report report_drc rule IDs; fix root cause (return to Stage 5)	user (confirm before any waiver)

---

Orchestration loop + STOP conditions

for stage in [0:static, 1:sim, 2:cdc, 3:synth, 4:impl, 5:signoff, 6:bitstream+reconfirm]:
    run stage
    pull FRESH evidence with the gate's tools
    if gate PASS:
        continue
    else:
        STOP. Do not advance. Hand the specific evidence to the owner skill.

Note the ordering: signoff (Stage 5) gates the implemented design before the bitstream is written (Stage 6). You never advance to generate_bitstream until setup AND hold timing, routing, DRC, and methodology are all green.

Hard STOP conditions (do not advance, do not retry blindly):

• Any gate fails on fresh tool output.
• A long async run shows STATUS = ERROR / aborted in get_run_status / sim_get_sim_status.
• You would have to silence a real violation (false_path / multicycle / waiver / disable_rule) to make a gate go green.
• You have tried one safe strategy/constraint change at a stage and it did not cross the gate — escalate, do not loop through strategy permutations.

Do not thrash: at most one safe remediation attempt per stage within this skill (e.g., default impl strategy missed timing -> try one Performance strategy). Beyond that, present options + costs and hand to the specialist. Constraint/strategy changes come before any RTL change, and RTL changes are recommended to the user, never silently applied.

---

Safety rails (do not violate)

1. Evidence before claims. "Bitstream is valid / timing met / DRC clean / CDC clean" requires fresh post-implementation tool output in THIS session (extract_timing_metrics, report_route_status, report_drc, report_methodology). A returned generate_bitstream or a green run_full_flow line is not proof of signoff. Synthesis numbers never prove signoff.
2. Signoff before bitstream. The post-route signoff gate (Stage 5) runs on the open implemented design before generate_bitstream. Never write a bitstream on an unverified design; never reorder these.
3. No fake-pass. Never apply set_false_path, set_multicycle_path, set_max_delay, waive_lint_violation, disable_lint_rule, or set_clock_groups to make a violation disappear. Exceptions are legal only when the path is genuinely exempt — state the assumption explicitly, and if the item could be real (a CDC, an actual long path), ask the user first.
4. Smallest safe change first. Constraints/strategy before RTL. Default strategy before exotic strategy. One change-class per iteration so the next measurement attributes cause to effect.
5. Never proceed on a vacuous pass. Zero constraint files / zero clocks / no testbench are NOT passes — they are missing verification. Call them out and get user direction.
6. Recommend RTL edits; do not silently rewrite the design. Use read_file/read_file_lines to cite the issue; propose the edit; let the user (or an explicit instruction) approve update_file/replace_in_file.
7. Long flows use async + poll. Synthesis, implementation, and long simulation go through *_async + get_run_status / sim_get_sim_status, never a blocking call that risks a timeout mid-build.
8. Real tools only. Use only the exact SynthPilot tool names. If a needed capability (e.g., explicit checkpoint export, or automated incremental compile) is not in the catalog, say so rather than inventing a tool. Vivado runs persist their own state on disk, and open_synthesized_design / open_implemented_design reopen a run for analysis — you do not need (and must not invent) a separate checkpoint-write tool.
9. Surface trade-offs then stop. When safe options are exhausted, present the options and their costs (area/power/effort/risk) and hand back to the human.

---

Output format

Report the flow as a gate table, then a verdict. Show before/after where a remediation was attempted.

=== FULL-FLOW DEMO — <project> @ <part>, top=<top> ===

Prereqs:  connection OK | project OK | top OK | constraints=<N clocks> | tier=<...>

Stage gates (fresh evidence):
  [PASS] 0 Static     syntax clean; lint: 0 err / <w> warn
  [PASS] 1 Sim        TB PASS (<runtime>, self-checking)
  [PASS] 2 CDC (RTL)  0 critical crossings (check_cdc_lint)
  [PASS] 3 Synth      COMPLETE; clocks=<list>; util fits (LUT x%/FF y%); report_cdc 0 critical
  [PASS] 4 Impl       route_design COMPLETE
  [PASS] 5 SIGNOFF    WNS=<+ns> AND WHS=<+ns> (all clocks) | 100% routed | DRC 0 err | methodology clean
  [PASS] 6 Bitstream  written -> <path/to.bit>; re-confirm: 100% routed, DRC 0 err
Artifacts:   <.bit> [, <.xsa> / <.mcs> / programmed device]

VERDICT: PASS — signoff gate (Stage 5) met on fresh post-route evidence; bitstream written and re-confirmed.
         (or) STOPPED at Stage <n>: <one-line failure> -> handed to <skill> with <evidence>.

Rules for the report:

• Every [PASS] must cite the tool that proved it; an unproven stage is [UNVERIFIED], never [PASS].
• The final VERDICT: PASS is permitted only when Gate 5 is green — setup (WNS ≥ 0 / TNS = 0) and hold (WHS ≥ 0 / THS = 0) across all clocks, 100% routed, DRC 0 errors, methodology clean — on fresh extract_timing_metrics + report_route_status + report_drc + report_methodology output, and Gate 6 confirms the bitstream was written with signoff still holding. Otherwise report exactly which gate stopped the flow and which specialist skill now owns it.