Step 1: Identify the relevant industry for "ENI S.P.A."
Eni S.p.A. is a major international integrated oil and gas company. Based on the provided industry methodologies, it falls under the "Oil And Gas Exploration And Production" (E&P) sector. We will apply the baseline formulas and make necessary adjustments based on the E&P and general corporate methodology.

Step 2: Estimate 2021 Adjusted_EBITDA
EBITDA (reconstructed) = Profit Loss From Operating Activities + Depreciation And Amortisation Expense + Impairment Loss Reversal Of Impairment Loss Recognised In Profit Or Loss + Write Off Of Tangible And Intangible Assets
For 2021 (ending 2022-01-01):
Operating Profit = 12,341,000,000
D&A = 7,063,000,000
Impairment = 167,000,000
Write-offs = 387,000,000
EBITDA = 12,341,000,000 + 7,063,000,000 + 167,000,000 + 387,000,000 = 19,958,000,000 EUR

Adjustments:
- adjustment_leases: Under S&P methodology, 1/3 of lease interest is added back to EBITDA. Lease interest = 1/3 of lease payments. Lease payments = 939,000,000. Lease interest = 313,000,000. Adjustment = 313,000,000.
- nonrecurring_losses/gains: Net other operating income expense = 903,000,000. We exclude this nonrecurring item to normalize EBITDA.
- pension_adjustments: None detailed.
- joint_venture_proportional_EBITDA: None required (equity method).
- other_normalization_adjustments: 0
Adjusted_EBITDA (2021) = 19,958,000,000 + 313,000,000 - 903,000,000 = 19,368,000,000 EUR

Step 3: Estimate 2021 FFO
FFO = Adjusted_EBITDA - cash_interest - cash_taxes
- cash_interest: Finance Costs (4,216,000,000) + Lease interest (313,000,000) = 4,529,000,000.
- cash_taxes: Income Taxes Paid (3,726,000,000).
FFO (2021) = 19,368,000,000 - 4,529,000,000 - 3,726,000,000 = 11,113,000,000 EUR

Step 4: Estimate 2021 Adjusted_Debt
reported_debt = Shortterm Borrowings + Current Portion Of Longterm Borrowings + Longterm Borrowings
reported_debt (2021) = 2,299,000,000 + 1,781,000,000 + 23,714,000,000 = 27,794,000,000
leases = 8 * lease payments = 8 * 939,000,000 = 7,512,000,000
pension_deficit = 0 (Net Deferred Tax Assets and Pension Provisions are not netted as a deficit here)
guarantees = 0
hybrid_debt_portion: Eni has perpetual subordinated bonds classified in equity (Reserve of Exchange Differences/Other Reserves). In 2021, there was a net issue of 2,000,000,000. Per S&P, equity-credited hybrids are treated as 50% debt. hybrid_debt_portion = 2,000,000,000 * 0.5 = 1,000,000,000.
other_debt_like_items = 0
eligible_cash = Cash And Cash Equivalents = 8,254,000,000
Adjusted_Debt (2021) = 27,794,000,000 + 7,512,000,000 + 1,000,000,000 - 8,254,000,000 = 28,052,000,000 EUR

Step 5: Calculate 2021 Adjusted_Debt / Adjusted_EBITDA
Ratio (2021) = 28,052,000,000 / 19,368,000,000 = 1.448x

Step 6: Calculate 2021 FFO / Adjusted_Debt
Ratio (2021) = 11,113,000,000 / 28,052,000,000 = 0.396 (39.6%)

Step 7: Estimate 2022 Adjusted_EBITDA
EBITDA (reconstructed) = 17,510,000,000 + 7,205,000,000 + 1,140,000,000 + 599,000,000 = 26,454,000,000 EUR
Adjustments:
- adjustment_leases: Lease payments = 994,000,000. Lease interest = 331,333,333. Adjustment = 331,333,333.
- nonrecurring_losses/gains: Other operating income expense = -1,736,000,000. Exclude this to normalize.
Adjusted_EBITDA (2022) = 26,454,000,000 + 331,333,333 - (-1,736,000,000) = 28,521,333,333 EUR

Step 8: Estimate 2022 FFO
FFO = Adjusted_EBITDA - cash_interest - cash_taxes
- cash_interest: Finance Costs (9,333,000,000) + Lease interest (331,333,333) = 9,664,333,333.
- cash_taxes: Income Taxes Paid (8,488,000,000).
FFO (2022) = 28,521,333,333 - 9,664,333,333 - 8,488,000,000 = 10,369,000,000 EUR

Step 9: Estimate 2022 Adjusted_Debt
reported_debt (2022) = 4,446,000,000 + 3,097,000,000 + 19,374,000,000 = 26,917,000,000
leases = 8 * 994,000,000 = 7,952,000,000
hybrid_debt_portion: Outstanding perpetual subordinated bonds equity balance represents the cumulative issuance. In 2022, the equity accounts show cumulative net issues (seen in Other Reserves changes and transactions). Total hybrid capital is treated as 50% debt. Outstanding equity hybrids = 2,000,000,000 (from 2021 issue) + 2,000,000,000 (from 2020 issue) = 4,000,000,000. hybrid_debt_portion = 4,000,000,000 * 0.5 = 2,000,000,000.
eligible_cash = Cash And Cash Equivalents = 10,155,000,000
Adjusted_Debt (2022) = 26,917,000,000 + 7,952,000,000 + 2,000,000,000 - 10,155,000,000 = 26,714,000,000 EUR

Step 10: Calculate 2022 Adjusted_Debt / Adjusted_EBITDA
Ratio (2022) = 26,714,000,000 / 28,521,333,333 = 0.937x

Step 11: Calculate 2022 FFO / Adjusted_Debt
Ratio (2022) = 10,369,000,000 / 26,714,000,000 = 0.388 (38.8%)

Step 12: Classify the year-on-year credit trend
Signal 1 (Leverage):
Change in Adjusted_Debt / Adjusted_EBITDA = 0.937x - 1.448x = -0.511x.
This is ≤ -0.2x, so Signal 1 is Improving.

Signal 2 (Cash-flow coverage):
Change in FFO / Adjusted_Debt = 0.388 - 0.396 = -0.008.
This is between -0.03 and +0.03 (exclusive), so Signal 2 is Stable.

Combining the two signals:
Since one signal is Stable and the other is Improving, we return the non-Stable category (Improving), as per the workflow instructions.

<answer>Improving</answer>