T2860 - FIX invoice loop range and skip cancelled invoices on Odoo 18

[danpa32]

• Fix off-by-one in _generate_invoices loop range: use advance_billing_months + month_interval - 1 as upper bound so the correct number of invoices is produced for all billing cycle combinations
• Exclude cancelled invoices from _should_skip_invoice_generation so that a cancelled invoice no longer blocks regeneration for the same period
• Expand readme (DESCRIPTION, USAGE, DEVELOP) with billing cycle docs

[gemini-code-assist]

Code Review

This pull request updates the invoice generation loop upper bound to correctly handle monthly and annual billing cycles, excludes cancelled invoices from deduplication, and adds comprehensive documentation. However, a critical issue was identified where the implementation of _should_skip_invoice_generation still uses an exact match on invoice_date, contradicting the newly added documentation and design principles. It is recommended to update the query to use a date range covering the full billing interval.

Important

The consumer version of Gemini Code Assist on GitHub is being sunset. Starting June 18, 2026, new organization installations will be blocked, and all code review activity will officially cease on July 17, 2026.
For more details on the timeline and next steps, please review the Help Documentation.

[greptile-apps]

Confidence Score: 5/5

The changes are narrowly scoped to recurring invoice duplicate checks and regeneration behavior.

No correctness issues were identified in the reviewed change set, and the implementation aligns with the described invoice-regeneration behavior.

T-Rex Logs

What T-Rex did

• T-Rex produced a proof for a posted P1 finding and referenced the corresponding review comment for details.
• T-Rex validated the invoice-range behavior; the before and after captures show the same result, confirming no change in this scenario, and the invoice-range-probe.py harness was used for the checks.
• T-Rex validated the cancelled-invoice-regeneration behavior; the before-state lacked the state exclusion with matched_invoice_ids=[900] and should_skip_invoice_generation=True, while the after-state added the not-in state and produced no matches with should_skip_invoice_generation=False.

_{Ran code and verified through T-Rex}

Comments Outside Diff (1)

1. General comment

   Invoice generation loop still uses old upper bound, so advance billing with a starting offset skips the final cycle

   • Bug
     • The PR claims _generate_invoices fixes the off-by-one invoice generation range by using an upper bound equivalent to advance_billing_months + month_interval - 1, but head still contains range(starting_offset, group.advance_billing_months + 1, group.month_interval) at the invoice_offset loop. Executed before/after evidence shows no behavior change from base: with starting_offset=1, advance_billing_months=12, and month_interval=12, head generates only offset [1] / date 2026-02-01, while the claimed behavior would include [1, 13] / dates 2026-02-01 and 2027-02-01. The same mismatch appears for advance_billing_months=6, month_interval=3, where head produces [1, 4] instead of [1, 4, 7].
   • Cause
     • The intended range upper-bound change was not applied in recurring_contract/models/contract_group.py; line 308 still stops at group.advance_billing_months + 1, which excludes the next interval when starting_offset is nonzero.
   • Fix
     • Update the loop upper bound in _generate_invoices to the claimed interval-aware bound, e.g. range(starting_offset, group.advance_billing_months + group.month_interval, group.month_interval) or the exact equivalent required by the product spec, and add regression coverage for nonzero starting_offset with annual and quarterly intervals.

   _{Ran code and verified through T-Rex}

_{Reviews (5): Last reviewed commit: "[T2860] recurring_contract: exclude canc..." | Re-trigger Greptile}

[ecino]

@copilot When _calculate_start_date_and_offset() returns starting_offset = 1, the new upper bound can make the loop empty. With the default monthly setup (advance_billing_months = 1, month_interval = 1), this becomes range(1, 1, 1), so a waiting contract configured to skip the current month does not generate the next-month invoice at all. The previous loop still produced offset 1 for that path. Can you fix that PR?

[Copilot]

@copilot When _calculate_start_date_and_offset() returns starting_offset = 1, the new upper bound can make the loop empty. With the default monthly setup (advance_billing_months = 1, `month_inte...

Fixed in 3c8c592. I updated the loop upper bound to include starting_offset, so the starting_offset=1, monthly default path now generates offset 1 instead of producing an empty range.